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Protein hydrolysates as biostimulants in horticulture
... As defined by the new Regulation (EU) 2019/1009, the function of biostimulants is to stimulate plant nutrition processes independently of the product's nutrient content, underlying their different use and origin [8]. Among the various ones, protein hydrolysates (PHs) from legumes are a well-known group of natural biostimulants that have been proven to prevent yield losses and improve quality in vegetables under stressing conditions [9]. Plant-derived PH biostimulants contain free amino-acid and soluble peptides, which stimulate the accumulation of protective compounds with antioxidant activities in plants, minimizing the impact of abiotic stresses on crops [10]. ...
... Plant-derived PH biostimulants are available in liquid, soluble powder, or granular form [9]. They are preferred to animal-derived PH biostimulants for their greater agronomic value [10]. ...
... They are preferred to animal-derived PH biostimulants for their greater agronomic value [10]. Indeed, plant-derived biostimulants exert both direct and indirect beneficial effects on crops: they have been proven to stimulate auxin-and gibberellin-like activities involved in plant metabolism (direct effect) [11,12], and increase root surface area, thus enhancing nutrients and water uptake (indirect effect) [9,11]. ...
Recently, the use of plant-derived biostimulants has been suggested as a sustainable way to improve the nutritional quality of tomato and mitigate the effects of environmental stresses. In this regard, a two-year experiment was conducted in open field on four cultivars of tomato (two commercial tomatoes and two local landraces of long shelf-life tomato), to assess the crop response, in terms of fruit yield and quality traits, to the foliar application of two plant-derived biostimulants based on protein hydrolysates (PH), under opposite water regimes (no irrigation and full irrigation), in a semi-arid environment of South Italy. Tomato plants in field were sprayed with a solution containing one of the two biostimulants approximately every 15 days. Full irrigation significantly promoted plant productivity, leading to yields the 22 % and 57 % higher than those produced under no irrigation. Biostimulants significantly promoted plant productivity (+57 % and +39 %, respectively under no and full irrigation, on the average of the two biostimulants), although in the first year only. Overall, fruit quality was better in fruits produced in plants exposed to prolonged soil water deficit. Biostimulants, across cultivars and water regimes, had no effect or even declined fruit quality in terms of total solids (TS), soluble solids (SS), titratable acidity (TA), reducing sugars (RS). The antioxidants were higher in fruits produced under prolonged soil water deficit. Except in the two commercial tomatoes, lycopene content was greater under full irrigation. Overall, the effects of biostimulants on the antioxidants were rather inconsistent. Significant interactions among the three experimental factors on fruit quality traits suggest that the application of biostimulant should be modulated according to water regime and cultivar, involving specific open-field experiments. Interesting correlations (positive or negative) among all the examined traits were described in the current study. A PCA analysis was conducted to reduce the dimensionality of dataset considering the large number of variables in combination. PCA analysis allowed to distribute cultivars and treatments in four distinct groups, according to quality traits. Fluctuating results between the two years of experiment indicated that the tomato response to the application of biostimulants is strictly season-dependent. Future multi-sites and multi-year research are needed to fine-tune the use of biostimulants and, ultimately, make the crop more economically and environmentally convenient than the cultivation of untreated plants.
... The upsurge in crop yield encouraged by non-microbial biostimulants (V-PHs and PEs) under favorable, sub-or supra-optimal, or unfavorable growing environments could be related to various direct and indirect collaborative physiological phenomena, comprising the elicitation of enzymatic actions, triggering of hormone-like activity, and modulation of the plant root system, which leads to advanced absorption capacity of water and nutrients [32,33]. Simultaneously, within the biostimulants panorama, microbial biostimulants, such as plant growth-promoting rhizobacteria (PGPR), arbuscular mycorrhizal fungi (AM), or Trichoderma spp., substantially promote plant growth and productivity, in addition to nutritional and functional quality [34][35][36][37][38]. Trichoderma spp. ...
... Overall, data on most tomato productive and growth traits revealed a positive effect of the three biostimulants. This is in accordance with the results of Colla et al. [32], who studied the effect of different biostimulants (plant extract and protein hydrolysate) on tomato plants and reported an increase in productive features. Moreover, our data corroborate those of Sani et al. [51], who stated that tomato plants treated with Trichoderma spp. ...
... Biostimulants promoted fruit total polyphenols. As reported by Colla et al. [32] and López-Bucio et al. [58], the application of microbial and non-microbial biostimulants has a positive effect on plant secondary metabolism activity and, consequently, the biosynthesis of polyphenols. The small peptides and amino acids comprising the PE and PH had a hormone-like effect on plants, with positive outcomes on the stimulation of secondary metabolites [5]. ...
The need to increase yield and enhance the sustainability of crop production systems has led to the development and employment of natural products, such as plant biostimulants. In recent years, a number of reports have researched the effects of biostimulants on plant performance; however, few studies have focused on the mutual application of microbial and/or non-microbial biostimulants. This research, conducted in the framework of the SO.MI.PR.O.N regional project, aimed to investigate the single or mutual application of three biostimulants, a tropical plant extract (PE), a vegetal protein hydrolysate (PH), and Trichoderma atroviride, on ‘Creativo’ F1 cherry tomato plants cultivated during two growing cycles (2022–2023 and 2023–2024). Our results showed that plants treated with the combination Tricho + PE + PH had statistically significant higher fresh shoot biomass (+64.2%, 1647.0 g plant−1), total fruit production (+37.9%, 1902.5 g plant−1), marketable fruit production (+52.9%, 1778.5 g plant−1), and average weight of marketable fruits (+53.1%, 17.0 g) compared to control plants (untreated plants). Furthermore, biostimulant treatments, especially T. atroviride, variably enhanced cherry tomato fruits’ qualitative traits, such as firmness, total soluble solids, ascorbic acid, lycopene, and total polyphenols compared to control plants. Overall, the best combinations to increase tomato fruit qualitative features were PE + PH, Tricho + PE, and Tricho + PH. From an economic point of view, the best treatment for achieving the highest net return was PE. This study underlines that biostimulant features (yield, qualitative aspects, and economic profitability) can be supported through the application of specific biostimulant combinations.
... Leaf permeability is a crucial factor, and the penetration of biostimulants into plant tissue is a necessary condition for reliable efficiency [16]. Additionally, foliar application increases amino acid and peptide availability for their uptake by plants by reducing competition with soil microorganisms compared with soil application [17]. ...
... Alkaline and acidic hydrolysis require strong experimental conditions and extreme precautions [38,39], and such conditions attack all peptide bonds, resulting in a very high degree of hydrolysis and the release of free amino acids. However, it also destroys several amino acids: tryptophan is usually destroyed with acidic hydrolysis, cysteine, serine, and threonine are partially lost, and asparagine and glutamine are converted into their acidic forms [17]. The large use of acids and alkalis can also lead to an increase in salinity in the FPH. ...
... In addition, racemization occurs during chemical hydrolysis. This means that there is a conversion of the free amino acids from the L-form to the D-form, which may cause some problems in terms of the effectiveness of the FPHs, for example, as biostimulants, as plants cannot directly use D-form amino acids in their metabolism [17]. ...
Crop production has become a priority issue in recent years because of the exponential growth of the world’s population and the need to find substitutes for chemical fertilizers. The latter is under the spotlight in order to achieve a more sustainable approach in a cost-effective way. Biostimulants have gained attention as an alternative to chemical fertilizers. Although they are not considered fertilizers as inputs of nutrients, they stimulate plants’ nutrition and tolerance to stress, among other characteristics. In the literature, amino acid-based biostimulants have been found to be effective. This review focuses on the effectiveness of biostimulants, their presence in the global market, and their production with fish by-products as a source, using enzymatic hydrolysis and autolysis, with a particular focus on fish viscera, their possibilities in the agricultural sector, and their availability in Europe for possible opportunities. Fish viscera protein hydrolysates for biostimulant production seem a feasible alternative to fishmeal production in Europe, especially in areas located far from fishmeal plants.
... Three types of biostimulants are recognized: humic substances (HSs), hormonecontaining products (HCPs), and amino acid-containing products (AACPs) [2]. The latter are of particular interest because of their demonstrated beneficial effects on crop productivity [5], mitigation of abiotic stress [6], and enhancement of microbiome diversity [7]. In addition, they can be obtained from the by-products of agro-industry through protein hydrolysis, reducing the impact of agriculture on the environment whilst being economically attractive [8,9]. ...
... Based on their contents, PHs can be divided into two categories: (i) mixture of peptides and amino acids of plant or animal origin; and (ii) mixture of individual amino acids such as glutamate, glutamine, proline, and others [10]. Besides peptides and amino acids, PHs can contain carbohydrates, minerals, phenols, and phytohormones, as well as some other organic substances, whose concentration is usually negligible [5]. Due to food safety concerns regarding PHs from animal sources, mainly linked to bovine spongiform encephalopathy, their use was prohibited by the EU in 2014 (European Regulation No. 354/2014). ...
... Sources of proteins can vary greatly, and some of the most common ones are shown in Figure 2. Besides peptides and amino acids, PHs can contain carbohydrates, minerals, phenols, and phytohormones, as well as some other organic substances, whose concentration is usually negligible [5]. ...
Agriculture is facing challenges to produce more food in a climate scenario that works in the opposite direction. To amend this, agriculture has to invent new ways of making more with less. Interest in using by-products and finding new ways to utilize them has been increasing in recent years. The use of protein-rich sources for protein hydrolyzation and the use of these protein hydrolysates as biostimulants in plant production have been increasing. These mixtures are mainly produced by chemical and enzymatic hydrolysis from agro-industrial protein-rich by-products of animal, plant, and algal origins. The application of PHs has the potential to alleviate environmental stress; improve plant growth; and increase productivity, fruit yield, and abiotic-stress tolerance in agricultural crops. The use of these biostimulants offers a way to reduce the use of agrochemicals and agrees with the “do more with less” task in the future of agricultural production. This review gives an insight into the production of PHs, referring to sources of raw materials and methods of hydrolysis, the uptake and translocation of PHs, their effect on plant growth, the development and physiology, their role in alleviating stressful conditions, and their use in agriculture. The beneficial effects of PHs on different aspects of plant physiology, metabolism, and plant functioning under stressful conditions are evident. Inconveniently, crops, and sometimes even cultivars, are affected differently based on the way that PH is applied, the timing, and the concentration applied. Further research is needed to elucidate the mechanisms by which the components of PHs modify plant physiology and metabolism.
... Therefore, symptoms of chlorosis are reported in higher dosages of AA fertilizer foliar application. 234 As per future perspectives, trials should be conducted to optimize the correct dosage, dilution of application, cropspecific AA toxicity levels, AA signaling, and sensing mechanisms 234 during different modes of action; dose optimization for preservatives to maintain AA consistency are suggested to be established through in vitro testing. Additionally, there is a critical need to identify mechanisms for tolerating abiotic stress such as drought, cold, heat, and biotic stresses with BH application, and assessing disease severity of different crops, seed germination, antioxidant capacity, and soil microbiology improvements upon BH application are underexplored. ...
... Therefore, symptoms of chlorosis are reported in higher dosages of AA fertilizer foliar application. 234 As per future perspectives, trials should be conducted to optimize the correct dosage, dilution of application, cropspecific AA toxicity levels, AA signaling, and sensing mechanisms 234 during different modes of action; dose optimization for preservatives to maintain AA consistency are suggested to be established through in vitro testing. Additionally, there is a critical need to identify mechanisms for tolerating abiotic stress such as drought, cold, heat, and biotic stresses with BH application, and assessing disease severity of different crops, seed germination, antioxidant capacity, and soil microbiology improvements upon BH application are underexplored. ...
Accurate fertilization is of paramount importance in modern agriculture for maintaining the expected productivity. Continuous application of urea fertilizer to meet the nitrogen (N) requirement of plants causes detrimental effects; alternatively, shifting to eco-friendly biogenic hydrolysate (BH) rich in plant biostimulants is crucial. While many studies have sought to extract and characterize BHs rich in amino acids (AAs) in agriculture, systematic reviews on animal-based BHs and their effect on plant health and defense are relatively rare. This Review presents a comprehensive analysis that (1) identifies the importance of animal-based enriched BHs to plant growth, immunity development, and stress control; (2) presents the modulation of mechanisms inside plants; and (3) discusses recent case studies, successful applications, regulations, and potential future outcomes. This work paves the way for the identification of a pioneering sustainable approach for boosting crop productivity and resilience, opening the gate for a paradigm change in agriculture.
... The EU Regulation 2019/ 1009 defines PB as products able to promote one or more plant or plant rhizosphere characteristics including (i) nutrient use efficiency, (ii) tolerance resistance to (a)biotic stress, (iii) quality characteristics and (iv) availability of confined nutrients (EU, 2019). Within the broad group of PB both microbial (plant growth promoting rhizobacteria (PGPR) belonging to Azotobacter, Azospirillum and Rizhobium spp.) and non-microbial (humic substances, silicon, seaweed extracts and protein hydrolysates) substances are encompassed (Alzate Zuluaga et al., , 2022Battacharyya et al., 2015;Calvo et al., 2014;Canellas et al., 2015;Colla et al., 2017Colla et al., , 2015Pii et al., 2015;Rouphael et al., 2015;Rouphael and Colla, 2020). Protein hydrolysates (pH) are a mixture of amino acids and peptides obtained by the partial degradation of animal or vegetal protein sources . ...
... Previous study highlighted the antagonistic effect of auxin and cytokinin at low to medium concentrations thus the cytokinin signalling is suppressed by auxin action (Kurepa et al., 2019). This may suggest that the biostimulant C in N limiting conditions could have exerted an auxin-like activity as already detected Colla et al., 2015;Lucini et al., 2020), inducing the down-regulation of genes involved in the cytokinin response. This could be further confirmed by the detection of an up-regulated gene encoding for an auxin-responsive protein belonging to five BP terms concerning cellular responses. ...
... Combinations of amino acids and peptides, such as oligopeptides and polypeptides, make up biostimulants based on amino acids (Colla et al., 2015). Agricultural wastes, such as crop leftovers and animal wastes, are hydrolyzed chemically and enzymatically to produce amino acids and peptide combinations (such as collagen and epithelial tissues) (Calvo et al., 2014;du Jardin, 2015;Halpern et al., 2015). ...
... The microbiological and enzymatic activities of the soil are enhanced. The quantity, density, and length of lateral roots also increased and was followed by an increase in nitrate reductase activity (Colla et al., 2015). Moreover, PHs enhance the physiochemical quality of fruits by increasing their levels of carotenoids, flavanoids, polyphenols, aromatics, and pungency (Sharma et al., 2018). ...
... Moreover, protein hydrolysates primarily act by stimulating the expression of nitrate transport genes (NRT1.1 and NRT2.1) and activating plasma membrane H + -ATPase proton pumps [27]. The latter mechanism is further enhanced by the activation of genes involved in secondary metabolite synthesis through the phenylpropanoid pathway, which may explain the increased phenolic compounds observed in our study. ...
... Copper, iron, zinc, and magnesium are essential for chloroplast metabolism and enzymes, components of the electron transport chain and chlorophyll structure; the high levels of these elements following biostimulant treatments were likely associated with the overexpression of transporters, such as COPT2 for copper and NRAMP3 for iron and zinc translocation [43]. Interestingly, the amino acids derived from protein hydrolysates are useful for preserving the protein structure needed for cell division, facilitating cellular division, enlargement, differentiation, and the effective formation of polyamines aiding mineral absorption activities [27]. The amino acid profile of spirulina, including methionine, glycine, and cysteine, was demonstrated to optimise nutrient uptake, translocation, and metabolism, also enhancing the uptake of nitrogen, phosphorus, and potassium as well as root development [37]. ...
Increasing interest is being devoted to environmentally friendly strategies, such as the use of plant biostimulants, to enhance crop performance and concurrently ensure food security under the perspective of sustainable management. The effects of two biostimulant formulations (protein hydrolysate and spirulina) on four Italian traditional storage onion cultivars (Ramata di Montoro, Rossa di Tropea, Rocca Bruna, Dorata di Parma) were investigated in Naples province (southern Italy), in terms of yield, quality, shelf-life, bioactive compounds, and mineral composition. Ramata di Montoro showed the highest levels of yield (66.4 t ha−1) and vitamin C (31.5 mg g−1 d.w.) and the longest shelf-life (228 days). Significant increases in marketable yield were recorded under the applications of both protein hydrolysate (+15.5%) and spirulina (+12.4%) compared to the untreated control. The two biostimulant formulations significantly increased bulb shelf-life and the contents of polyphenols (201.4 mg gallic acid eq. 100 g−1 d.w. on average vs. 158.6 of the untreated control), vitamin C (26.8 mg g−1 d.w. on average vs. 22), and both lipophilic and hydrophilic antioxidant activities. These findings demonstrate the effectiveness of both protein hydrolysate and spirulina as sustainable tools for enhancing both yield and quality parameters within the frame of environmentally friendly farming management.
... Recent research has shown that PHs may directly affect plants by boosting the metabolism of carbon and nitrogen and their hormonal function. PHs may have indirect impacts by enhancing nutrient availability and increasing nutrient acquisition and efficiency (14), regulating the uptake of nitrogen by the main assimilation-processing enzymes and regulating the activity of tricarboxylic acid cycle enzymes, namely citrate synthase, isocitrate dehydrogenase and malate dehydrogenase. The application of PHs may improve the diversity and abundance of the plant microbiome, which will aid in the plant's ability to endure biotic and abiotic challenges and obtain more water and nutrients (15). ...
... In particular, PHs originating from vegetable by-products and the wet-milling of corn are becoming increasingly common and well-liked in the scientific community and business sectors since they may offer a cost-effective, environmentally beneficial and long-lasting solution to waste disposal issues (31). Animal-derived proteins obtained by acid hydrolysis are the major sources of PHs biostimulants; the remaining portion is acquired from the enzymatic hydrolysis of proteins originating from plants (14). ...
Nutritional security and minimizing the impact of farming practices on the environment are major challenges in modern farming systems. Currently, the horticulture sector is growing fast and moving towards sustainability and profitability. Indiscriminate and improper use of chemical inputs to ensure high yields of horticultural products could lead to significant contamination of soil and water bodies. Under these circumstances, farmers must optimize their input management to reduce pollution and preserve the economic margin by following sustainable production practices. The use of precision horticulture techniques is more sustainable than conventional to intensive farming methods. Among the various eco-friendly inputs, plant biostimulants are highly effective and can enhance plant growth and production as well as mitigate the adverse effects of abiotic stressors. Protein Hydrolysates (PHs) are a significant class of plant biostimulants based on amino acid and peptide mixtures. Because of their beneficial effects on crop performance, PHs has drawn increased amounts of attention recently. Compared with other biostimulants microbial biostimulants are more prevalent in crop production. A new approach is the formulation of a mixture of plant growth-promoting microorganisms/microbe-derived metabolites and protein hydrolysates as single biostimulants, to nourish the soil, plants and microbes. This review presents a thorough summary of recent research on the postulated modes of action of PHs and microbial biostimulants in horticultural crops. Furthermore, this study highlights the potential of protein hydrolysates and microbial biostimulants and the potential of the protein-rich microbial biostimulants to make horticulture more profitable and to safeguard the environment.
... Results are in line with the findings of previous studies, where humic substances promoted plant growth and development by improving photosynthesis-related parameters in potato (Man-hong et al. 2020), chrysanthemum (Fan et al. 2014), pea (Khan et al. 2013) and orange jasmine (Fascella et al. 2021). Similarly, application of PH has been found to enhance the photosynthetic rate, resulting in a higher yield with better quality harvest in many crops (Colla et al. 2015;Rouphael et al. 2017). The observed increase in the photosynthetic rate of PH-treated plants aligns with the results of our prior investigation conducted on tea nursery plants (Raguraj et al. 2022b). ...
... In agreement with our results, animal-origin PH improved the leaf N, P and K content in Petunia plants (Cristiano and De Lucia 2021). It has been reported that PH interferes with hormonal activities through bioactive peptides (Colla et al. 2014(Colla et al. , 2015 and indirectly affects plant nutrition (du Jardin 2015). Next to PH, foliar application of HLS also increased the N and P concentration in leaves compared to the control, which agrees with the findings reported on lettuce (Haghighi et al. 2012), tomato (Suh et al. 2014) and pepper (Akladious and Mohamed 2018). ...
This study was designed to investigate the effects of individual and combined application of protein hydrolysate (PH) and humic-like substances (HLS) along with the reduction of fertilizer on the growth, physiological and biochemical parameters and mineral nutrition of tea nursery plants. Individual and combined effects of biostimulants were evaluated in a randomized complete block factorial experimental design with three replications. The experiment consisted of three levels of fertilizer (100%, 75% and 50%) and four biostimulant treatments (Control, PH, HLS and PH + HLS). Combined (PH + HLS) and individual application of biostimulants increased the leaf count and number of active buds by 44.8% and 52.3% respectively, compared to untreated plants. PH and combined treatments produced significantly higher and comparable total plant biomass under 75% and 100% fertilizer levels compared to control + 100% fertilizer. Positive effect exerted by HLS alone on total plant biomass was comparatively lower than PH and PH + HLS while significantly higher than control. PH application significantly increased the net photosynthetic rate (+ 30%), stomatal conductance (+ 48%) and concentration of CO2 in intracellular space (+ 36%) compared to control plants. All the biostimulant treatments positively affect the chlorophyll, total soluble sugars and proline contents in tea leaves, where higher values were recorded in PH treatment. Leaf N concentration was significantly increased by individual application of PH and HLS, while leaf P concentration was enhanced by PH and combined treatments. Leaf K, Mg and Ca concentrations were not influenced by biostimulant treatments. PH and combined treatments produced higher and similar effects on the growth of tea nursery plants with 75% and 100% fertilizer levels while HLS alone showed comparatively lower positive effects. It can be concluded that foliar application of PH alone or combining PH with HLS enhanced the growth performance of tea nursery plants along with a saving of chemical fertilizer by 25%.
... The use of these products (via soil or leaves) has several benefits to plants. Moreover, according to Colla et al. (2015), some of the peptides enclosed in PH act as signalling molecule, having hormone-like activity. Interestingly, it was reported that protein hydrolysates can be beneficial to withstand environmental stresses, such as those prompted by extreme temperatures, drought, or minerals (Tuteja, 2007). ...
... Conversely, the positive effect of PH on dry matter content can be linked to its effect on nitrogen metabolism. Indeed, as evidenced by Colla et al. (2015), amino acids included in PH play a significant role in boosting N accumulation and transport. The positive effect of AM inoculation on dry matter content can be related to an increased uptake and nutrients translocation (Xie et al., 2022). ...
... There are several categories of biostimulants, including protein hydrolysates (Colla et al., 2015), algal extracts (Battacharyya et al., 2015), and leaf (e.g., moringa, Rashid et al., 2021) extracts, among others. The use of food, agricultural or industrial by-products as sources of biostimulants is receiving much attention due to its dual function: reduction/removal of a waste product and production of a biologically active ingredient for commercial purposes (Xu and Geelen, 2018). ...
Biostimulants help plants to cope with abiotic stresses and using those obtained by recycling waste bioproducts is
an eco-friendly technology with great potential. Quinoa (Chenopodium quinoa Willd.) is a highly nutritious grain
originally cultivated in the Andes but now spreading worldwide. Before consumption, quinoa seeds undergo a
dehulling process that produces large amounts of a waste product rich in saponins and other bioactive compounds.
In this study, the by-product of quinoa seed dehulling (quinoa hull powder, QHP) was analysed for its
plant biostimulant activity. The objective was to analyze whether QHP could improve growth and induce
biochemical and transcriptional changes under control or saline (25, 50, and 100 mM NaCl) conditions in the
model plant Arabidopsis thaliana. QHP was supplied either by pre-soaking seeds prior to sowing (seed priming) or
added to the seedling growth medium. Complete and partial recovery of germinability to control levels was
observed in seeds primed with 0.05 mg mL 1 QHP in the presence of 50 and 100 mM NaCl, respectively.
Seedlings transferred to QHP-supplemented saline medium showed improved shoot and root biomass and primary
root length as well as reduced oxidative stress (MDA, and H2O2 production). RT-qPCR analysis of stress-responsive
genes revealed that some were induced by QHP alone, while salt-induced expression of others was
modulated by QHP. The phytochemical composition of QHP suggests that, in addition to saponins, protective
compounds, such as proline, spermidine, carotenoids, and polyphenols, could be potentially responsible for its
activity.
... MGEE and DBHS are cheap and easy to prepare by agricultural producers, especially as environmental stresses continue to increase through the adverse impacts of climate change. As an eco-friendly strategy, natural PBs, including MGEE and DBHS, are innovations that improve plant growth, flowering, fruit-setting, yielding, yield quality, and water and nutrient use efficiencies, as a result of increased plant tolerance to abiotic stresses (Colla et al. 2015;Rady 2018;Rouphael and Colla 2020). ...
Due to climate change, abiotic stresses have arisen and are harming agricultural water management and agricultural productivity worldwide. To address this issue, bio-stimulators have been explored to improve water management and nutrient use efficiency, reflecting improved agricultural productivity due to suppression of climate change-induced stresses and the improved plant stress tolerance. Bio-stimulators play a dual role as they increase tolerance to abiotic stresses and feed the plant to adapt to stress and survive. Maize grain embryo extract (MGEE) and diluted bee-honey solution (DBHS) are a novel group of bio-stimulators recently used, beginning in 2014, for some crop plants (common bean, faba bean, sunflower, wheat, maize, onion, atriplex, roselle, and chili pepper) grown under certain abiotic stressors (salinity, drought, cadmium, nutrient deficiency, and chemical fertilizers). Reports signalized that MGEE and DBHS effectively induce improvements in molecular and morpho-physio-biochemical indices and positive stimulation of antioxidant defense systems, all of which enable plants to cope with stress-stimulated toxicity and maintain basic metabolic capacity under abiotic stress. Under the above-mentioned stresses, MGEE and DBHS can provide efficient mechanisms to enhance plant growth and yield traits, yield quality characteristics, photosynthetic efficiency, low-molecular-weight antioxidants, nutrient and hormonal homeostasis, antioxidant redox states, enzymatic antioxidant activities, antioxidant and polyamine gene expressions, etc. Extensive research into the potential of MGEE and DBHS to sustain plant performance under adverse field conditions would strengthen their potential as a cheaper and eco-friendly alternative to harmful and high-cost chemicals.
... Notably, WP exhibited a particle size range ranging from 190.1 to 995.4 nm, while WPH4 displayed a more confined range of particle size, measuring from 78.82 to 995 nm, as visually depicted in Fig. 2. The size and chemical characteristics of the particles play a pivotal role in facilitating particle mobility through stomatal pores, with smaller particles exhibiting an increased propensity to permeate the microscopic openings of the stomata. derived from hydrolyzed organic materials from both animal and plant sources [48][49][50][51]. Furthermore, the amino acid composition of WPH closely mirrors the composition of commercial biostimulant AGRO-SORB ® Folium biostimulant, as indicated by [52]. ...
In modern agriculture, using industrial co-products as plant biostimulants provides a sustainable approach to meet the growing demand for organic fertilizers. In this study, whey protein (WP), a co-product from the dairy industry, was utilized to promote plant biostimulant. WP was hydrolyzed using acid protease to produce Whey Protein Hydrolysate (WPH); the particle size of WPH ranges from 78 to 995 nm and contains 15 free amino acids. The amino acids of WPH aspartic acid, glutamic acid, serine, and glycine were predicted using iPath, highlighting their importance in carbon and nitrogen assimilation processes. Seed priming with 1.5% WPH significantly enhanced S. lycopersicum germination rates (83.93%), vigor index (682.9), and germination index (3.58%), while toluidine blue staining revealed improved root hair promotion. In the greenhouse trial, foliar application of 15% WPH resulted in higher protein content and accelerated carbon and nitrogen assimilating enzymes than control plants. Moreover, key genes related to these metabolic pathways, such as CS, ICDH, MDH, GS, and NR, were up-regulated by 3.26, 2.73, 1.46, 1.18, and 1.17-fold, respectively. These findings align with the principles of the circular economy and promote sustainable agricultural practices.
... In recent years, several novel approaches have been developed to enhance sustainable production in horticulture crops. Biostimulants are a possible tool that may enhance fruit quality, improve nutrient utilization efficiency, and increase resistance to abiotic stress (Colla et al., 2015;Rouphael and Colla, 2020). Biostimulant refers to plant protection and nutritional product frameworks. ...
By the year 2050, the global population is projected to reach around 9.1 billion, leading to a corresponding increase in the need for food to feed the growing population. Horticultural crops, including fruits, have been identified as a significant source of nutraceuticals. Plant biostimulants have gained much importance over the last decade to improve sustainable production. Plant biostimulants may be significantly increased within fruit crops to obtain high fruit yield. Furthermore, they can completely transform the study of fruit set, growth, and development. In recent years, there have been remarkable technological developments in plant biostimulants to study fruit biotechnology to achieve sustainable production. This chapter focuses on new advancements in plant biostimulants in fruits over the past few years. In addition, it also offers new insights into how these plant biostimulants will expedite advanced research in fruit biotechnology. An in-depth analysis and discussion of plant biostimulants’ technical challenges and inherent limitations are necessary to improve our understanding of this field.
... One promising solution in sustainable agriculture involves the use of biostimulants, which contain organic substances or microorganisms that, when applied to plants or soil, can enhance plant growth [2], improve nutrient uptake [3], increase resilience to abiotic stress (such as drought, salinity, nutrient deficiency, and extreme temperatures) [4][5][6][7], and promote overall plant health [8]. Unlike synthetic chemicals, which can lead to soil degradation [9], loss of biodiversity [10], and negative impacts on human health [11], biostimulants offer a sustainable alternative that aligns with ecological principles and circular economy practices [12]. ...
This study explores the potential of honey as a natural soil amendment to enhance plant growth and biochemical resilience in Ocimum basilicum L. Honey solutions at varying concentrations (2.5%, 5%, and 10%) were applied to evaluate their effects on growth parameters , biomass accumulation, and antioxidant activity. The results revealed that lower honey concentrations (2.5%) had a minimal impact on plant height, while higher concentrations (5% and 10%; −42% and −43%, respectively) exhibited inhibitory effects, suggesting a dose-dependent response. The leaf count remained stable across treatments, indicating a consistent morphological outcome. The biomass analysis highlighted variability in the plant biomasses, reflecting the influence of honey concentrations on plant energy allocation. Despite unchanged chlorophyll and ascorbic acid levels, significant enhancements in antioxidant compounds and activity were observed, particularly at lower concentrations (antioxidant activity at 2.5% and 5%; +26% and +30%, respectively), underlining the role of honey in bolstering the antioxidant defense system. These findings demonstrate honey's dual role as a growth modulator and antioxidant enhancer, emphasizing its relevance in sustainable agricultural practices. This research contributes to the development of eco-friendly strategies for improving crop performance and resilience through the application of naturally derived biostimulants.
... The amino acids from enzymatic hydrolysis of plantorigin proteins are one of the bioactive compounds widely studied that promoted vegetative growth (Cerdán et al. 2013;Colla et al. 2015). In addition, they play an essential role in metabolic processes and as a building block of proteins (Pratelli and Pilot 2014). ...
The increasing consumer interest in organic products is driving the rise of the agricultural sector. However, organic farming productivity was lower than conventional due to the reduction of external inputs, synthetic fertilizers, and pesticides. In this context, the use of organic biostimulant emerged as a promising solution. The aim of this study was to evaluate the efficacy of three doses (0.1, 0.2, 0.3 mL per plant) of an innovative organic biostimulant based on amino acids and seaweed extract (Lombrico® ARREL), on cucumber (Cucumis sativus L.) under hydroponic conditions in a plant growth chamber. The results demonstrated that the root application of the biostimulant promoted plant growth development. In the shoot, there was an increase in height, number of leaves, fresh and dry weight and leaf area compared to the control. In the root, there was an increase in volume (66.2, 83.2, and 165%), fresh weight (45.0, 61.0 and 97.3%) and dry weight (7.0, 23.0 and 53.7%) as escalating the product dose (low, medium and high, respectively) compared to the control. Furthermore, the root length decreased, triggering a significant modification of the root system architecture. Transcriptome analysis in the root revelated that this biostimulant induced change in the gene expression. Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEEG) analysis showed stimulation of the cell division, biosynthesis and remodeling of the cell wall, increasing plant metabolism and hormone signal transduction, as well as activating the phenylpropanoid biosynthesis. This study showed the benefit of integrating the biostimulant uses in organic agriculture management to improve plant development, thereby enhancing crop productivity.
... A promising solution is the use of growth-promoting biostimulants that include molecules and/or microorganisms enhancing plant fitness in terms of plant growth, productivity, and nutrient utilization efficiency. Additionally, biostimulants may have the capacity to bolster tolerance against a broad spectrum of abiotic and biotic stresses [12][13][14] . ...
Enhancing crops productivity to ensure food security is one of the major challenges encountering agriculture today. A promising solution is the use of biostimulants, which encompass molecules that enhance plant fitness, growth, and productivity. The regulatory metabolite zaxinone and its mimics (MiZax3 and MiZax5) showed promising results in improving the growth and yield of several crops. Here, the impact of their exogenous application on soil and rice root microbiota was investigated. Plants grown in native paddy soil were treated with zaxinone, MiZax3, and MiZax5 and the composition of bacterial and fungal communities in soil, rhizosphere, and endosphere at the tillering and the milky stage was assessed. Furthermore, shoot metabolome profile and nutrient content of the seeds were evaluated. Results show that treatment with zaxinone and its mimics predominantly influenced the root endosphere prokaryotic community, causing a partial depletion of plant-beneficial microbes at the tillering stage, followed by a recovery of the prokaryotic community structure during the milky stage. Our study provides new insights into the role of zaxinone and MiZax in the interplay between rice and its root-associated microbiota and paves the way for their practical application in the field as ecologically friendly biostimulants to enhance crop productivity.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-024-82833-6.
... The term "biostimulant" refers to a broad and heterogeneous class of substances and microorganisms that, regardless of their nutrient content, can improve nutrition efficiency, tolerance to abiotic stresses, and crop quality characteristics when applied to plants or rhizosphere (European Union 2019). One prominent category within the biostimulants includes protein hydrolysates (PHs)e.g. a mixture of free amino acids and polypeptidesof biomasses, often sourced from agro-industrial by-products of animal, plant, or microbial origins (Calvo et al. 2014;Colla et al. 2015;du Jardin 2015;Bastianelli et al. 2023). Numerous studies have documented the beneficial impacts of hydrolysates on the growth, yield, and fruit quality of various crops, whether applied via nutrient solutions in hydroponic systems, soil applications, or foliar sprays (Ertani et al., 2009;Morales-Payan and Stall, 2003;Parrado et al., 2008Parrado et al., , 2007Santi et al., 2017;Zhou et al., 2022). ...
Plant‐derived biostimulants have gained attention in agricultural practices for their potential to enhance crop quality and resilience. In this study, we investigated the effects of applying a maize gluten‐derived protein hydrolysate at the soil level in vineyards on berry quality in a table grape variety, the Black Magic early table grapevine, during veraison. Our results demonstrate significant improvements in various parameters 14 days after application, including increased anthocyanin levels, enhanced sugar accumulation, and larger berry diameter while maintaining berry firmness. Transcriptomic analysis revealed mechanisms underlying these effects, highlighting the biostimulant's ability to expedite ripening processes while selectively modulating genes associated with cell wall metabolism, thus explaining the observed preservation of berry firmness. Furthermore, the treatment with a gluten‐derived protein hydrolysate enhanced the grapevine's resilience to abiotic and biotic stresses, and several related genes were affected. This study sheds light on the potential of plant‐derived biostimulants in grapevine cultivation, emphasizing the need for further research to elucidate their mechanisms and optimize agricultural practices.
... La parroquia Santa Rita se caracteriza por un clima tropical húmedo, con una temperatura media anual de 26°C y una precipitación anual de 1200 mm, lo cual proporciona condiciones ideales para el cultivo de plátano (28). La humedad relativa promedio es del 85%, con una altitud de 30 metros sobre el nivel del mar, y suelos predominantemente franco-limosos, bien drenados y ricos en materia orgánica (29). Estos factores ambientales crean un entorno propicio para el crecimiento y desarrollo de cultivos tropicales, facilitando el establecimiento de ensayos agrícolas controlados (9). ...
La producción de plátano enfrenta numerosos desafíos para garantizar un crecimiento óptimo y calidad de las plántulas durante la aclimatación. En este sentido, la utilización de microorganismos eficientes nativos son una alternativa biotecnológica para adaptar plantas in vitro. El presente trabajo tiene como objetivo evaluar el impacto de bioestimulantes en el crecimiento y calidad de las plántulas de dos variedades de plátano, Barraganete y Hartón. La investigación se realizó en Santa Rita, Manabí, Ecuador, utilizando plántulas propagadas in vitro y trasplantadas en bolsas de polietileno con una mezcla de tierra agrícola, compost y arena de río. Se midieron variables como altura de planta, diámetro del pseudotallo, peso seco de raíces, peso seco total, área foliar e índice de clorofila. Los resultados mostraron que los ácidos húmicos y los aminoácidos incrementaron significativamente la altura de las plantas (hasta un 25%) y el peso seco de raíces (hasta un 30%) en Barraganete
... It can achieve inactivation of pathogenic bacteria, removal of heavy metals, and stabilization of refractory organic matter (Dewil et al. 2006;Barber 2016;Wang et al. 2021). Studies have shown that humic and fulvic acids (Canellas et al. 2015), along with chitosan (Pichyangkura and Chadchawan 2015), plant or animal protein hydrolysis products (Colla et al. 2015), algal extracts (Battacharyya et al. 2015), and inter-root beneficial microorganisms (Ruzzi and Aroca 2015), are the main stimulant components. Stimulants improve N assimilation and C metabolism, increase growth hormone and gibberellin-like activities, and enhance antioxidant enzyme activities and secondary metabolite production, which can improve soil quality and ultimately enhance crop yield and quality Ceccarelli et al. 2021). ...
Production of liquid fertilizers containing nitrogenous nutrients and biostimulants from sewage sludge (SS-NB) has been attracting increasing attention due to its excellent fertilization effect and resource recycling attributes. To better understand the functional effects of nutrients and biostimulants in SS-NB on soil, the adsorption capacity and mechanism of straw biochar (SB) and wood chip biochar (WCB) for alkaline and neutral SS-NB components were investigated. The adsorption of total organic carbon (TOC) from alkaline and neutral SS-NB by WCB was 61.14% and 89.73%, respectively, higher than that by SB, which was 56.25% and 83.36%. Moreover, TOC from neutral SS-NB was more readily adsorbed, especially for fulvic and humic acids. SB had a strong adsorption capacity for calcium ions and nitrogen (TKN, nitrate N, protein, amino acid) and released large amounts of P. In addition, WCB and SB showed a strong affinity for macromolecules (proteins) and reducing substances (lignin and lipids) and excellent fixation ability for phytohormones and allelochemicals. However, WCB adsorbed more types of molecular substances than SB while maintaining a high immobilization rate. Analysis of the adsorption mechanism showed that surface amino groups of the biochar were involved in adsorption, while WCB had additionally high adsorption efficiencies through pore adsorption, hydrogen bonding adsorption and pore size-exclusion effects. The study revealed that biochar can be used as an efficient adsorption carrier for SS-NB to improve soil fertility management.
... Moreover, natural growth stimulants are also considered as biostimulants, for example, humic acid, fulvic acid, salicylic acid, protein hydrolases, or phenols (Chiaiese et al., 2018). Microbial organisms such as bacteria and fungi also represent an important category of biostimulants, known to modify soil fertility through degradation processes and enhance plant growth by restricting the pathogenic microbial population (Battacharyya et al., 2015;Colla et al., 2015). Biostimulants may support various metabolic activities happening in soil and plants as well as facilitate the uptake of nutrients. ...
Nanobiostimulants, comprising nanoparticles and biostimulants, represent an emerging and promising domain within agricultural science. The integration of these specialized nanomaterials into agricultural practices aims to boost crop productivity while concurrently moderating the adverse impact of environmental stresses on plant life. The current use of chemical fertilizers poses significant risks to human health and ecological networks, making the application of nanobiostimulants a compelling alternative. These stimulants demonstrate the potential of strengthening plant growth along with enhanced nutritional value, improving productivity, prolonging shelf-life, and reinforcing plants against biotic and abiotic stressors. Despite their potential, the widespread adoption of nanobiostimulants faces challenges. The lack of comprehensive knowledge regarding the complex interrelationship between biostimulants, nanoparticles, and plant biology hampers their broad recognition and utilization in agricultural sector. Addressing this gap necessitates extensive research and exploration to formulate more suitable and commercially viable nanobiostimulants for the global farming community. This book chapter highlights the role of nanobiostimulants in addressing the challenges caused by both abiotic and biotic stresses in plants. The assessment underscores the critical importance of optimizing the synergistic interaction between nanoparticles and biostimulants to ensure efficient delivery and release at the specifically targeted sites, thereby creating effective and precise nanobiostimulants. The development of more sophisticated and practical nanobiostimulants is a pressing need, requiring the application of state-of-the-art methodologies to comprehend the multifaceted factors that drive agricultural success.
... Biostimulants are known to promote plant growth, development and productivity, according to numerous studies (Saa, 2015;Bulgari et al., 2015), but the exact mechanism of action is unclear or not known. It is possible that the positive effects of biostimulant on growth parameters could be attributed to auxin and gibberellin-like activity, as well as enhanced nitrogen uptake, as documented for the biostimulant action of plant-derived protein hydrolysate in maize, tomato and gibberellin-deficient dwarf pea plants (Colla et al., 2014). Reactive oxygen/nitrogen species and hormonal signalling were linked to yet another proposed function of biostimulants. ...
The use of plant biostimulants in agriculture has increased. Only a few reports have provided information on plant biostimulant's effects on fruit quality, which is related to appearance, chemical composition, and physical characteristics. Plant biostimulants have primarily been studied in relation to their stress attenuation capabilities. They have a sustainable appeal because they are organic, satisfying the demand of customers concerned about the advantages of eating healthier food. This chapter makes clear how little information there is on this subject. It is recommended that future research concentrate on each stage separately because fruits have distinct metabolisms at each stage of their life cycle, from pollination to harvest and after-harvesting. Therefore, research should focus on forming quality while the fruits are still attached to the plant and extending shelf life after harvest.
Climate change significantly impacts agriculture by increasing the frequency and intensity of environmental stresses, which can severely reduce agricultural yields. Adopting sustainable practices is crucial to mitigating these risks and enhancing crop resilience. Applying natural compounds and microorganisms as biostimulants has gained popularity as an eco-friendly approach to alleviating abiotic stress in agricultural plants. This study reviews the current research on applying biostimulants in horticulturally significant crops to boost their resistance to abiotic stressors such as salinity, drought, and high temperatures. It explores the mechanisms through which these stimulants offer protection, focusing on the roles of key bioactive substances in regulating physiological and molecular processes for stress adaptation. The study addresses biostimulant formulation, regulation, and application challenges. Future research directions are suggested to harness biostimulants’ potential fully, aiming to develop climate-resilient horticultural systems that follow sustainability principles. This comprehensive review underscores the use of biostimulants as a sustainable strategy to increase crop yields in the face of climate change, reducing reliance on synthetic agrochemicals.
Spices are high-value, low-volume, export-oriented crops that are frequently used to season and flavour food and drink. Despite the wide range of phytochemicals found in spices, the nutraceutical preparation of these plants frequently centres on a few key bioactive metabolites. With its numerous physiological effects, curcumin in turmeric, capsaicin in chillies, piperine in black pepper, [6]-gingerol in ginger, and saponin in fenugreek are all extremely helpful in medicine. The term spiceutical is gaining momentum among major spice-processing industries of the country. Scientific and technological progresses are undoubtedly key factors in obtaining quality-improved spices derived from innovative technologies, which have remarkable potentialities. The strategies outlined here to develop next-generation spices for nutraceuticals are intended to change the face of spice research in the days to come because it is in line with needs. Genetic control over quality characteristics makes it possible to successfully improve genotypes through breeding methods in spices. Spice quality criteria can be improved with the help of modern biotechnological intervention combined with traditional breeding methods. The whole genome and transcriptome-based approaches have shown to be more effective than earlier techniques and are quickly taking the lead in NGS research on spices. Certain nutraceutical substances’ underlying metabolic pathways and important genes can be better understood by applying the functional genomics/metabolomics method. A system biology approach will help plant breeders create nutraceutical cultivars that will enhance human health in general. The success of this endeavour would be dependent on the partnerships between governmental and private crop breeding institutions and human health research organizations.
depletion and injury caused by the overuse of strong synthetic chemicals or fertil
izers (Le Mire et al. 2016). By 2050, the world’s human population is expected to reach 9.7 billion. Excessive fertilizers and pesticide use have negative consequences for humans and other organisms. Around one million humans die every year as a result of pesticide poisoning due to overexposure. The usage of fertilizer or chemi
cals has been linked to subsurface water pollution, air pollution, aberrant weed and
The goal of the field experiment, which took place in 2020–21 at the Instructional Farm, Department of Fruit Science, College of Horticulture and Forestry, Jhalawar (AU Kota), was to investigate the physical–chemical properties of soil in the rhizosphere of guava (Psidium guajava L.) cv. Sardar, as well as the singular and synergistic impact of bio-stimulants. Nineteen treatments were analysed in a randomised block design with three replications, including three bio-stimulants applied through soil drenching: silicon, seaweed and humic acid. The results of the study showed that the application of bio-stimulants, specifically T12 (humic acid 15 g + seaweed 60 g), greatly improved the pH, electrical conductivity, organic carbon content and nutrient availability of the soil. In addition, microbial populations within the rhizosphere demonstrated a significant increase, particularly in favourable weather circumstances. These results highlight the ability of bio-stimulants to improve plant development and soil health in guava plantations. Comprehending the complex interplay between soil parameters and bio-stimulants might provide valuable insights for sustainable farming methods that aim to optimize yield while reducing ecological footprint. To further understand the long-term impacts and underlying mechanisms of bio-stimulants mediated changes in soil fertility and microbial activity, more study in this field is necessary.
Nonpathogenic microorganisms are known to be part of the normal gut microflora of animals and specifically play vital roles in fish physiology. They have wide-ranging bioactive molecules with high potential to fish’s general health. However, in some instances, it has been reported that irregular gut microbial interactions, pH, and nutrient fluctuations limit the potential activities and benefits of gut microflora. Therefore, as an alternative, the bioactive molecules of this nonpathogenic organism are biotechnologically harnessed and processed for use as additives in fish feeds, by identifying, mass culturing, extracting their extracellular metabolites, and processing them into storable forms for subsequent use. The biotechnology of producing extracellular metabolites from living things, in particular, microorganisms, is now feasible from previously identified and characterized nonpathogenic isolates. Biotechnological applications use biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific purposes essentially targeted at benefitting humans as end users. Research has shown that optimization of microbial growth and extraction of their metabolites for therapeutic and nutritional purposes are now gaining more relevance and adding high value to aquaculture production, concerning aquaculture nutritional biotechniques. They can secrete a full complement of secondary metabolic products which are known to be effective therapeutics such as antibiotics, growth promoters such as amino acids, and other biomolecules like enzymes that catalyze metabolism. This chapter therefore focuses on the sources, types, and uses of metabolites. The nutrient requirements of microbial growth, biotechnological, and bioeconomic relevance will also be discussed for sustainable activities in the Global South.
O objetivo deste trabalho foi avaliar o potencial dos hidrolisados da biomassa de Arthrospira platensis na aceleração da germinação e no desenvolvimento das plântulas de tomate. Para os experimentos foi utilizado como substrato o papel germitest umedecido em água deionizada e sementes de tomate selecionadas. Inicialmente, verificou-se o embebimento da semente com os volumes de 0,5 e 1 mL de água deionizada. Após, para cada teste de germinação utilizou-se 54 sementes de tomate (n=4) embebidas com os hidrolisados ou água (controle). Um planejamento experimental foi empregado para otimizar as condições de concentração do ácido sulfúrico e tempo de hidrólise. A comparação de biomassa de 5 para 10% (m/v) foi avaliada para o desenvolvimento das plântulas e número de sementes germinadas. Ambos os volumes de embebimento foram satisfatórios e com isso optou-se pelo uso de 0,5 mL para os ensaios com os hidrolisados. Os números de sementes germinadas obtidas pelos ensaios do planejamento experimental indicaram que as melhores condições de hidrólise ácida foram a concentração de 1% (v/v) de H2SO4 por 30 min. O aumento de biomassa de 5 para 10% (m/v) na hidrólise demonstrou ser promissora para o desenvolvimento da radícula. Dessa forma, o uso da biomassa de A. platensis mostra-se como uma alternativa adequada para a estimulação da germinação e aumento do desenvolvimento da radícula do tomate.
Current and future agricultural practices have to address a number of challenges, including increasing crop productivity and applying environmentally sensitive methodologies under conditions of climate change. In this context, the use of fungal metabolites is emerging as a strategy for ensuring agricultural and environmental sustainability while feeding the world’s growing population. In this chapter, we discuss the role of fungal phytopathogens as a source of metabolites for different agricultural applications. Particular attention is given to volatile compounds and cell-free filtrates as sources of bioactive metabolites. The application of fungal phytopathogen metabolites to promote plant growth, mitigate biotic and abiotic stresses, and provide a source of natural herbicides for weed control, are all considered, as are future perspectives. A review of the literature related to this field is presented, providing a comprehensive overview of our current understanding.
Currently every country is suffering from climate change and despite the ongoing efforts, there are still limited success stories for the improvement of plant abiotic stress resilience. The studies mainly focused on understanding the stress response and tolerance at the molecular level and utilizing it to another genotype with no tolerance. The strong interaction of plants with their environment is the main obstacle here, which prevents the outcomes of small-scale experiments to be repeated in the field. The inclusion of wild genotypes adapted to extreme environments in QTL studies and breeding efforts may stand as a promising approach for the improvement of abiotic stress tolerance. Agricultural practices including biostimulants, micronutrients and nanoparticles, genome editing, and engineering organelles can also lead to reduced yield loss. Understanding how stress memory is initiated and how to make it heritable even under favorable growth conditions is another approach that needs more investigation. The aim of this book chapter is to point out the fact that single efforts by themselves will not be enough for sustainability, and although there is still a gap between breeders, farmers, biodiversity scientists, agricultural engineers, molecular scientists, plant pathologists, and climate scientists, they should combine their knowledge to secure future generations.
The escalating impact of abiotic stress on crop productivity requires innovative strategies to ensure sustainable agriculture. This review examines the promising role of biostimulants in mitigating the adverse effects of abiotic stress on crops. Biostimulants, ranging from simple organic compounds to complex living microorganisms, have demonstrated significant potential in enhancing plant resilience, stress tolerance, and overall performance. The mechanisms underlying biostimulant action—such as enhancing antioxidant defenses, regulating hormonal pathways, and inducing metabolic adjustments—are reviewed. Furthermore, we incorporate the latest research findings, methodologies, and advancements in biostimulant applications for addressing abiotic stressors, including drought, salinity, high temperatures, and nutrient deficiencies. This review also highlights current challenges and future opportunities for optimizing biostimulant use in sustainable crop production. This revision aims to guide researchers and agronomists in applying biostimulants to improve crop resilience in the context of climate change.
Climate changes have exacerbated the progression of drought conditions on a global scalethreating to crop production and heightening concerns over food security. Water scarcity enforces alterations in fundamental morphology, physiology and biochemical traits in crops. Consequently, it is imperative to identify environmentally sustainable alternative solutions to mitigate this problem and enhance overall plant performance. In this sense, biostimulants have emerged as a promising alternative as they improve plant resilience, enhance physiological processes, and mitigate the detrimental consequences of water deficit conditions on crop production. This review compiles the latest research on the application of organic extracts and inorganic compounds in crops subjected to drought conditions, specifically humic acids, protein hydrolysates, seaweed extracts, and silicon. Moreover, it offers a comprehensive overview of the origins and effectiveness of these biostimulants, with a detailed analysis of their application and the associated physiological, biochemical, and genetic modifications induced by these bioactive compounds. This knowledge enhances the understanding of the efficacy and implementation strategies pertinent of these compounds under water stress scenarios in agricultural settings.
Since climate of the globe is changing abruptly, causing tremendous challenges (biotic and abiotic stresses) on the production of vegetable crops, it seems to be difficult to ensure the food security for the rapidly growing population of the world if sustainable production systems are adopted. Though farmers are indiscriminately applying inorganic fertilizers and plant protection chemicals to replenish the fertility of their fields and protect their plants from pests, the issue of sustainable production seems to have been forgotten. Thus, the use of organic factors of production is a must in order to overcome the challenges so that production of healthy products can be maintained in an eco-friendly manner through the utilization of Bio-stimulators. Bio-stimulants have a crucial role in enhancing the growth, development and overall performance of different vegetable crops belonging to different families; Solanaceae, Alliaceae, Amaranthaceae, and Brassicaceae. The most commonly utilized bio-stimulants in the field of agriculture worldwide are humic substances (humic acid and fulvic acid), plant or animal-based protein hydrolysates, macro and micro-algal extracts (seaweed extracts), silicon, arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria. Bio-stimulants have important role in enhancing the growth characteristics, yielding potential, biochemical compositions (concentrations of ascorbic acid, and carotenoid content) in tomato plants and in other plants belonging to Solanaceae family like eggplant. Application of different types of bio-stimulants results in the improvement of growth, yields and chlorophyll and allicin contents in the Alliaceae species (onion and garlic). In the vegetable crops belonging to the family of Amaranthaceae (Spinach and Amaranthus), bio-stimulants have important impacts in the improvement of seed germination, increasing of plant height, photosynthetic pigments, yield and nutritional composition. Increased plant growth, photosynthetic rate and stomatal conductance, yield parameters, phenolic and flavonoid compounds and seed fatty acid concentration are also the results of bio-stimulant applications in the brassica species (cabbage, broccoli, rapeseed, mustard). Thus, the sustainable agriculture systems could be guaranteed by using bio-stimulants to boost the production of vegetable crops both quantitatively and qualitatively.
Improper disposal of organic waste leads to greenhouse gases, pollution, and health risks. Anaerobic digestion offers a sustainable solution by converting this waste into biogas and digestates, which contain valuable nutrients and stimulatory organic compounds that can be recycled to improve plant growth and support food production. Here we review the transformation of liquid and solid digestates into biostimulants by microalgal cultivation, vermicomposting, and insect-based bioconversion. These processes yield phytohormones, polysaccharides, betaines, humic substances, chitin, protein hydrolysates, and growth-promoting microbes, that enhance plant growth and resilience against environmental stresses. Due to the variability in digestate composition, we emphasize the need for optimized formulations, a deep understanding of synergistic interactions among bioactive compounds, and standardized extraction techniques to support broader applications.
This review investigates the role of biostimulants in enhancing the abiotic stress tolerance of medicinal and aromatic plants. Biostimulants play a crucial role in promoting plant growth and increasing resistance to environmental stress conditions. The negative effects of abiotic stress types such as drought, salinity, temperature, and heavy metal stress on plants can be mitigated using these products. This review addresses various types of biostimulants, their effects on plant metabolism, and the outcomes of these applications on plant quality. The use of biostimulants in agriculture offers advantages such as the conservation of natural resources, improvement of soil health, and optimization of water usage. However, challenges such as the lack of standardization, insufficient knowledge and awareness, and regulatory processes limit the widespread use of these products. The review emphasizes the need for further research to enhance the effectiveness of biostimulants and develop new application strategies in the future. In conclusion, biostimulants are important tools with the potential to increase the productivity of medicinal and aromatic plants and should be considered as part of sustainable agricultural practices.
Rice (Oryza sativa), the primary food source for over half of the global population, is critical to food security but faces productivity challenges from suboptimal fertilizer use and associated environmental degradation in India. Addressing these issues necessitates innovative strategies that enhance crop performance while maintaining ecological balance. Biostimulants, known for their role in enhancing nutrient efficiency and crop resilience, offer a promising solution for optimizing fertilizer use and improving soil health. This study evaluates the efficacy of AGMA Bio Stimulant Granules on the growth, yield, and soil health of rice during the kharif season of 2023 at Bidhan Chandra Krishi Vishwavidyalaya, Kalyani, West Bengal. A randomized block design with eight treatments and three replications was employed, including combinations of AGMA granules with 100% and 80% recommended NPK doses. Results demonstrated significant improvements in growth parameters, yield attributes, and soil nutrient availability with AGMA application. Treatments T2 and T5, integrating AGMA granules with 100% and 80% NPK, respectively, achieved the highest grain yields, with T5 showing a 19% yield increase over the control. Soil health indicators, including organic carbon and available nitrogen, phosphorus, and potassium, improved significantly, while electrical conductivity decreased. The study concludes that AGMA Bio Stimulant Granules enable a 20% reduction in NPK fertilizer use without compromising yields, underscoring their potential to support sustainable and environmentally friendly agricultural practices.
Introducción. Los bioestimulantes son productos orgánicos que mejoran la absorción de nutrientes de las plantas, entre ellos sustancias húmicas, aminoácidos, extractos de algas y bacterias promotoras del crecimiento de las plantas; y se han identificado numerosos mecanismos y de selectividad de bioestimulantes para nutrientes específicos. Objetivo. Determinar el efecto de la aplicación de bioestimulantes en la producción de pepino y melón en invernadero. Materiales y métodos. Se evaluaron los bioestimulantes BioRemedy 2,0 g L-1, Grand Sill 2,0 g L-1, Fossil 5,0 g L-1, L-Amino 2,0 mL L-3 y un Testigo (con aplicación de solo agua), en tres estadios de desarrollo de los cultivos. El experimento fue establecido bajo un diseño experimental completamente aleatorio desbalanceado con 10 tratamientos. Cada unidad experimental estuvo constituida por tres hileras. Las variables de respuestas fueron: altura de planta, grosor de tallo, número de frutos, tamaño del fruto, volumen del fruto y peso de frutos (rendimiento). Resultados. Los bioestimulantes tuvieron mejor efecto en la altura de planta, diámetro de tallo, volumen de fruto en el pepino. En melón los bioestimulantes tuvieron mayor efecto en el volumen de fruto y peso. Se encontró que Fossil mostró mejor efecto para la altura de planta en ambas especies y el BioRemedy resulto ser el mejor para el diámetro de tallo, volumen de fruto, peso de fruto y número de frutos. Conclusión. El BioRemedy fue el mejor bioestimulante para el diámetro de tallo, el volumen y peso de fruto para el cultivo de pepino y melón. El L-amino tuvo mejor respuesta para diámetro de tallo en melón.
Ten products, commercially available as biostimulants or reported for their biostimulating properties, were tested under conventional and organic growing systems for their effects on mustard microgreens ( Brassica juncea ) grown in presence of abiotic (salt) or biotic ( Pythium ultimum ) stress. Drench application of wollastonite (calcium silicate) significantly improved the germination rate of mustard seeds sown in a substrate inoculated with P. ultimum in conventional growing system exclusively. In both growing systems, no significant effect of biostimulants was observed on the dry biomass or the proportion of healthy microgreens grown in presence of P. ultimum . None of the biostimulants significantly increased the germination rate of seeds exposed to a salinity stress in both growing systems while humic acid, triacontanol, chitosan, and Bacillus subtilis PTB185 significantly decreased the germination rate of seeds exposed to 40, 80 or 120 mM NaCl L ⁻¹ under conventional or organic management. Seed treatment with Trichoderma harzianum T-22 and humic acid resulted in microgreens with a significantly higher dry biomass when subjected to 40 and 80 mM NaCl L ⁻¹ under conventional and organic management, respectively. The study showed that the effects of the biostimulants vary from beneficial to detrimental and that plant response to biostimulants is influenced by the cultivation conditions.
Abiotic stresses like drought, high temperature spells and salinity can seriously deteriorate the crop yield, which can worsen the food supply scenario at global level. Recently, transcriptomics approach has been used for a finer and deeper analysis of stress response mechanisms and adaptation of plants experiencing stress conditions. Comparative study of stress-tolerant and stress-sensitive plant varieties at transcriptomics level can shed further light on stress-adaptive strategies in plants. Employing these approaches, some stress-associated mechanisms have been observed and further research is being done in terms of single cell transcriptomic analysis and developmental stage-specific analysis for further refined knowledge. Recently, many refined techniques such as microarray analysis, RNA-seq analysis, genomic-scale expressed sequence tags and next generation sequencing have been developed which are now being utilized for generating stress response related data and will enhance our understanding of stress-responsive mechanisms. The information obtained through these approaches will contribute toward developing plants especially crop plants better equipped to counter and adapt to various abiotic stress conditions without compromising their yield potential. Plant growth promoting rhizobacteria are an important group of rhizospheric microorganisms which help plants in mitigation of abiotic stress by acting as biostimulants and inducing modifications at molecular, biochemical and physiological levels. In this chapter, stress-responsive and adaptive mechanisms at transcriptomics level in plants exposed to various abiotic stress conditions such as high temperature, drought and salinity have been discussed. Transcriptomic alterations induced by plant growth promoting rhizobacteria in abiotic stress tolerance in plants are also discussed.
The current agricultural system is in search of new strategies to achieve a more sustainable production while keeping or even increasing crop yield and quality. In this scenario, the application of biostimulants constitutes a potent solution. In the current study, the impact of a blue‐green microalgal extract (MB) and a pig tissue hydrolysate (PTH) on rapeseed plants' development was characterized. Obtained results revealed a positive effect on yield parameters of plants treated with MB and, especially, PTH; this was associated to an improvement on the photosynthetic performance. Moreover, this study remarked the effects of biostimulants on plant phenology through their pivotal role in modulating developmental processes. More specifically, proteomic, metabolomic, and hormone content analyses revealed distinct alterations associated with the acceleration of phenology induced by biostimulant application. Additionally, some antioxidant enzymes and stress‐related compounds were up‐regulated upon MB and PTH treatments, indicating enhanced plant defense mechanisms in response to accelerated phenological transitions. Such findings highlight the intricate interplay between biostimulants and plant physiology, wherein biostimulants orchestrate rapid developmental changes, ultimately influencing growth dynamics. Altogether, the current study reveals that the application of both MB and PTH biostimulants promoted rapeseed plant phenology and productivity associated with an improvement in the photosynthetic machinery while boosting other physiological and molecular mechanisms.
Abiotic stresses are global challenges that cause significant drop in crop yield by interfering with the plant’s metabolism. Biostimulants have emerged as a potentially innovative and ecologically sustainable approach to enhance plant growth and crop productivity under stressful conditions. Through a comprehensive and critical analysis of existing literature, this review provides insight into the mechanisms and effects of biostimulants in promoting plant resilience under stressful conditions. These mechanisms include nutrient uptake enhancement, stress-responsive genes regulation, plant hormone biosynthesis, osmotic adjustment, and antioxidant activity, ultimately leading to improved plant growth and resistance to abiotic stresses. This review deals with major categories of plant biostimulants (seaweeds, microbial biostimulants, humic substances and protein hydrolysates) and explores the mechanisms by which these biostimulants alleviate abiotic stresses. By summarizing the diverse mechanisms and effects of these biostimulants, this review provides valuable insights into their potential application as sustainable strategies for mitigating abiotic stresses.
How can the world adequately feed more than 9 billion
people by 2050 in a manner that advances economic
development and reduces pressure on the environment?
This is one of the paramount questions the world faces
over the next four decades.
Answering it requires a “great balancing act” of three
needs—each of which must be simultaneously met.
First, the world needs to close the gap between the food
available today and that needed by 2050. This gap is in
part a function of increasing population and wealth. The
United Nations Population Division (UNPD) projects that
global population will most likely grow from 7 billion in
2012 to 9.3 billion by 2050.1 At least 3 billion more people
are likely to enter the global middle class by 2030,2 and
they will almost certainly demand more resource-intensive
foods such as meats and vegetable oils.3 At the same time,
approximately 870 million of the world’s poorest people
remain undernourished even today.4 When production
falls short of people’s needs, the world’s rich can outcompete
the poor and hunger increases.5 Without successful
measures to restrain food demand growth by the world’s
more affluent, available worldwide food calories will need
to increase by about 60 percent from 2006 levels if everyone
is to be sufficiently fed.
Fertilizer use in modern agriculture is highly inefficient; much of the applied fertilizer is released into the environment, causing environmental degradation. One way in which fertilizer use can be reduced without damaging plant nutrition is to enhance crop uptake of nutrients through the use of biostimulants. A broad definition of plant biostimulants, including substances sometimes categorized as biofertilizers or biopesticides, is used throughout this review: "Plant biostimulants are substances or materials, with the exception of nutrients and pesticides, which, when applied to plants, seeds, or growing substrates in specific formulations, have the capacity to modify physiological processes in plants in a way that provides potential benefits to growth, development, or stress response." This definition includes a variety of substances, four of which will be reviewed in this article: seaweed extract, humic substances, amino acids, and plant-growth-promoting bacteria. We will concentrate on the positive effects of biostimulant application on plant nutrient uptake, and the underlying mechanisms, which include positive changes in soil structure or nutrient solubility, root morphology, plant physiology, and symbiotic relationships, will be discussed. Recommendations for future research directions include finding the most promising substances, isolating the active ingredients and clearly demonstrating the mechanisms by which they affect nutrient uptake. The beneficial effects and mechanisms must be consistently demonstrated in greenhouse and field experiments.
The aim of the current work was to determine whether the use of a commercial plant-derived protein hydrolysate ('Trainer') could improve the growth and nitrogen uptake of maize and lettuce grown in a floating system using full strength and reduced nutrient solution concentrations (100 and 10%, respectively) (Experiment 2). In Experiment 1, 'Trainer' was applied to the maize roots at the following concentrations 0, 0.25, 0.50 and 2.5 ml L-1, whereas in Experiment 2, two concentrations (0, and 2.5 ml L-1) of 'Trainer' were used as foliar spray. Increasing 'Trainer' concentration from 0 to 2.5 ml L-1 significantly increased the plant height, shoot dry biomass, SPAD index and leaf nitrogen of maize, whereas an opposite trend was observed for the root-to-shoot ratio. In Experiment 2, at reduced solution concentration (10% of standard solution), weekly foliar applications of 'Trainer' at 2.5 ml L-1 increased the fresh weight biomass, SPAD index and leaf nitrogen in lettuce by 50, 11 and 11%, respectively. Thus the application of biostimulants could be considered as a good production strategy for obtaining high growth and yields of valuable crops with lower impact on the environment.
The aim of this study was to evaluate the biostimulant action (hormone like activity, nitrogen uptake, and growth stimulation) of a plant-derived protein hydrolysate by means of two laboratory bioassays: a corn (Zea mays L.) coleoptile elongation rate test (Experiment 1), a rooting test on tomato cuttings (Experiment 2); and two greenhouse experiments: a dwarf pea (Pisum sativum L.) growth test (Experiment 3), and a tomato (Solanum lycopersicum L.) nitrogen uptake trial (Experiment 4). Protein hydrolysate treatments of corn caused an increase in coleoptile elongation rate when compared to the control, in a dose-dependent fashion, with no significant differences between the concentrations 0.75, 1.5, and 3.0 ml/L, and inodole-3-acetic acid treatment. The auxin-like effect of the protein hydrolysate on corn has been also observed in the rooting experiment of tomato cuttings. The shoot, root dry weight, root length, and root area were significantly higher by 21, 35, 24, and 26%, respectively, in tomato treated plants with the protein hydrolysate at 6 ml/L than untreated plants. In Experiment 3, the application of the protein hydrolysate at all doses (0.375, 0.75, 1.5, and 3.0 ml/L) significantly increased the shoot length of the gibberellin-deficient dwarf pea plants by an average value of 33% in comparison with the control treatment. Increasing the concentration of the protein hydrolysate from 0 to 10 ml/L increased the total dry biomass, SPAD index, and leaf nitrogen content by 20.5, 15, and 21.5%, respectively. Thus the application of plant-derived protein hydrolysate containing amino acids and small peptides elicited a hormone-like activity, enhanced nitrogen uptake and consequently crop performances.
The aim of this study was to evaluate the biostimulant action (hormone like activity, nitrogen uptake, and growth stimulation) of a plant-derived protein hydrolysate by means of two laboratory bioassays: a corn (Zea mays L.) coleoptile elongation rate test (Experiment 1), a rooting test on tomato cuttings (Experiment 2); and two greenhouse experiments: a dwarf pea (Pisum sativum L.) growth test (Experiment 3), and a tomato (Solanum lycopersicum L.) nitrogen uptake trial (Experiment 4). Protein hydrolysate treatments of corn caused an increase in coleoptile elongation rate when compared to the control, in a dose-dependent fashion, with no significant differences between the concentrations 0.75, 1.5, and 3.0 ml/L, and inodole-3-acetic acid treatment. The auxin-like effect of the protein hydrolysate on corn has been also observed in the rooting experiment of tomato cuttings. The shoot, root dry weight, root length, and root area were significantly higher by 21, 35, 24, and 26%, respectively, in tomato treated plants with the protein hydrolysate at 6 ml/L than untreated plants. In Experiment 3, the application of the protein hydrolysate at all doses (0.375, 0.75, 1.5, and 3.0 ml/L) significantly increased the shoot length of the gibberellin-deficient dwarf pea plants by an average value of 33% in comparison with the control treatment. Increasing the concentration of the protein hydrolysate from 0 to 10 ml/L increased the total dry biomass, SPAD index, and leaf nitrogen content by 20.5, 15, and 21.5%, respectively. Thus the application of plant-derived protein hydrolysate containing amino acids and small peptides elicited a hormone-like activity, enhanced nitrogen uptake and consequently crop performances.
Plasmopara viticola, the causal agent of grapevine downy mildew, is one of the most devastating grape pathogen in Europe and North America. Although phytochemicals are used to control pathogen infections, the appearance of resistant strains and the concern for possible adverse effects on environment and human health are increasing the search for alternative strategies. In the present investigation, we successfully tested two protein hydrolysates from soybean (soy) and casein (cas) to trigger grapevine resistance against P. viticola. On Vitis vinifera cv. Marselan plants, the application of soy and cas reduced the infected leaf surface by 76 and 63%, as compared to the control, respectively. Since both hydrolysates might trigger the plant immunity, we investigated their ability to elicit grapevine defense responses. On grapevine cell suspensions, a different free cytosolic calcium signature was recorded for each hydrolysate, whereas a similar transient phosphorylation of two MAP kinases of 45 and 49 kDa was observed. These signaling events were followed by transcriptome reprogramming, including the up-regulation of defense genes encoding pathogenesis-related (PR) proteins and the stilbene synthase enzyme responsible for the biosynthesis of resveratrol, the main grapevine phytoalexin. Liquid chromatography analyses confirmed the production of resveratrol and its dimer metabolites, δ- and ε-viniferins. Overall, soy effects were more pronounced as compared to the cas ones. Both hydrolysates proved to act as elicitors to enhance grapevine immunity against pathogen attack.
Plant-derived protein hydrolysates represent new biostimulant products able to improve crop tolerance
to abiotic stresses. The aim of the study was to determine growth, root morphology, SPAD index,
chlorophyll fluorescence, leaf mineral composition, and metabolic profiling of greenhouse lettuce either
untreated or treated (root or leaf-root application) with a plant-derived protein hydrolysate. For foliar
application, plants were sprayed with a solution containing 2.5 ml L−1 of biostimulant, whereas for root
application, 100 mL of solution with the same concentration was applied to the growing medium at
weekly intervals. Lettuce plants were supplied with two nutrient solutions: non-salt control (1 mM NaCl)
or 25 mM NaCl. Salt stress decreased shoot and root dry biomass, SPAD index, chlorophyll fluorescence,
leaf mineral composition and increased foliar proline concentration. Root and leaf-root application of
the biostimulant increased fresh yield, dry biomass and root dry weight of lettuce under salinity conditions.
This was associated with an improvement of plant nitrogen metabolism and an increase of the
Fv/Fm-ratio efficiency in biostimulant-treated plants. Oxidative stress mitigation, increase in osmolytes,
changes in sterols and terpenes composition, as well as the less expected increase in glucosinolates were
also observed in biostimulant-treated plants grown under saline conditions. The present study proves
that the application of plant-derived protein hydrolysate increases plant performance when plants are
grown under salinity conditions. The most favorable metabolic profile was obtained when biostimulant
was applied to both roots and leaves.
The aim of the present study was to investigate the influence of spraying with Aminoplant on the yield of two spinach cultivars in the spring and autumn cultivations. The experiment was carried out in 2008 and 2009 in the experimental station of the University of Agriculture in Krakow, Poland. Three factors were taken into consideration: (1) cultivar: 'Rembrandt F 1 ' and 'Spiros F 1 '; (2) time of cultivation: spring and autumn; (3) dose of Aminoplant: control (without Aminoplant), 1.5 dm 3 ha -1 and 3.0 dm 3 ha -1 . The spinach yield was dependent on the time of production and cultivar type, and ranged between 18.6-44.8 t ha -1 . Both cultivars yielded better in autumn cultivation. Spraying with Aminoplant had no effect on spinach yield. Dry matter content in spinach leaves was between 6.3-11.2 g 100 g -1 . Spinach grown in the autumn had a greater content of dry matter in comparison to the spring cultivation. In 2009, 'Rembrant F 1 ' was characterized by greater dry matter content than 'Spiros F 1 '. Aminoplant in a dose of 3.0 dm 3 ha -1 lowered dry matter content in spinach leaves as compared to the control. The nitrate content in spinach was differentiated (558-3506 mg NO 3 kg -1 f.m.) and depended on the time of cultivation, the cultivar, and the Aminoplant dose.
Increasing interest is devoted to carbohydrates for their roles in plant immunity. Some of them are elicitors of plant defenses whereas other ones act as signaling molecules in a manner similar to phytohormones. This review first describes the main classes of carbohydrates associated to plant immunity, their role and mode of action. More precisely, the state of the art about perception of “PAMP, MAMP, and DAMP (Pathogen-, Microbe-, Damage-Associated Molecular Patterns) type” oligosaccharides is presented and examples of induced defense events are provided. A particular attention is paid to the structure/activity relationships of these compounds. The role of sugars as signaling molecules, especially in plant microbe interactions, is also presented. Secondly, the potentialities and limits of foliar sprays of carbohydrates to stimulate plant immunity for crop protection against diseases are discussed, with focus on the roles of the leaf cuticle and phyllosphere microflora.
The aim of this study was to determine the composition of nitrogen fractions in alfalfa and red clover, which differ in proteolytic activity, and to evaluate the effect of wilting on changes in nitrogen fractions in alfalfa and red clover herbage. Total nitrogen was divided into protein and non-protein nitrogen, and the amino acid profile of protein was analyzed. Buffer-soluble nitrogen (BSN), including buffer-soluble protein nitrogen (BSPN) and non-protein buffer-soluble nitrogen (NPBSN), was determined. The NPBSN fraction was further subdivided into peptide nitrogen, amino acid nitrogen, neutral detergent-insoluble nitrogen (NDIN) and acid detergent-insoluble nitrogen (ADIN). Wilting in the field to 40% dry matter content (the swath was tedded once) did not reduce the total nitrogen content of alfalfa and red clover herbage, although it affected the concentration of the BSNfraction, in particular NPBSN, and free amino acid nitrogen. During alfalfa wilting, the soluble protein content decreased and the concentrations of non-protein nitrogen compounds increased, mostly due to an increase in free amino acid nitrogen. A reverse trend was observed during red clover wilting – the concentrations of non-protein nitrogen compounds decreased and soluble protein content increased. A decrease was also noted in peptide nitrogen, NDIN and ADIN. Wilting of alfalfa and red clover had no adverse effect on the amino acid profile of protein. The concentrations of essential amino acids that limit milk protein synthesis, i.e. Lys, Met, His and Arg, did not decrease. Legume wilting in the field contributes to an increase in the concentrations of soluble nitrogen in the plant material intended for ensiling.
Two biostimulants, one derived from alfalfa plants (AH) and the other obtained from red grape (RG), were chemically characterized using enzyme linked immuno-sorbent assays, Fourier transform infrared (FT-IR) and Raman spectroscopies. Two doses (50 and 100 mL L⁻¹ for RG, and 25 and 50 mL L⁻¹ for AH) of biostimulants were applied to Capsicum chinensis L. plants cultivated in pots inside a tunnel. The experimental design consisted of the factorial combination of treatment (no biostimulant, plus AH, plus RG) at three doses (zero, low, and high) and two time-course applications (at the second and fourth week after transplantation) and the effects were recorded at flowering and maturity. Both biostimulants contained different amounts of indoleacetic acid and isopentenyladenosine; the AH spectra exhibited amino acid functional groups in the peptidic structure, while the RG spectra showed the presence of polyphenols, such as resveratrol. These results revealed that at flowering, RG and AH increased the weights of fresh leaves and fruits and the number of green fruits, whereas at maturity, the biostimulants most affected the fresh weight and number of red fruits. At flowering, the leaves of the treated plants contained high amounts of epicatechin, ascorbic acid, quercetin, and dihydrocapsaicin. At maturity, the leaves of the treated plants exhibited elevated amounts of fructose, glucose, chlorogenic, and ferulic acids. Moreover, green fruits exhibited a high content of chlorogenic acid, p-hydroxybenzoic acid, p-coumaric acid and antioxidant activity, while both AH- and RG-treated red fruits were highly endowed in capsaicin. The ¹H high-resolution magic-angle spinning (HRMAS)-nuclear magnetic resonance (NMR) spectra of red fruits revealed that both products induced a high amount of NADP⁺, whereas RG also increased glucose, fumarate, ascorbate, thymidine and high molecular weight species. Our results suggested that AH and RG promoted plant growth and the production of secondary metabolites, such as phenols.
Drought is one of the most significant abiotic stresses that limits the growth and productivity of crop plants. We investigated the physiological and molecular responses of tomato plants treated with Megafol® (Valagro S.p.A), under specific drought conditions. The goal was to evaluate the impact of Megafol®, a biostimulant composed of a complex of vitamins, aminoacids, proteins and betaines, in attenuating the negative physiological responses of drought. Tomato plants were grown in a greenhouse, and physiological parameters were collected using Scanalyzer 3D (LemnaTec, GmbH), a plant phenomics platform. Using this technology it is possible to dynamically study the effects of biostimulants, such as Megafol®, on plant development in terms of early detection of physiological plant stress responses. The results showed that drought-stressed plants treated with Megafol® were healthier in terms of the biomass produced and chlorophyll fluorescence, thus highlighting the higher tolerance to stress of the treated plants. The effects of Megafol® were also studied at a molecular level by analysing the induction of genes typically involved in drought stress responses. Our results demonstrate the efficacy of Megafol® to reduce drought-stress related damage in tomato plants.
Before sowing, the seeds of two wheat cultivars, S-24 and MH-97, were treated with three levels [(0 (water), 10 and 20 µM)] of triacontanol (TRIA) for 12 h. TRIA-treated seeds were grown in full strength nutrient solution for 24 days in a greenhouse, after which time, they were supplied with two salt treatments (0 and 150 mM NaCl). After 21 days of salt application, changes in the malondialdehyde (MDA), hydrogen peroxide (H 2 O 2) and total soluble proteins contents as well as activities of some key antioxidant enzymes (CAT, POD and SOD) were measured. Salinity stress of 150 mM NaCl significantly decreased the activity of SOD, while increased that of CAT, and enhanced the levels of MDA and H 2 O 2 contents in both cultivars under salt stress conditions. The outcome of salt stress was non-significant on soluble proteins and activity of POD. The effect of pre-sowing application of TRIA was non-significant on all measured attributes except that it significantly increased the activity of POD under non-saline conditions. The cultivar difference with respect to the different attributes measured in the present investigation was non-significant.
Background
Plant biostimulants are diverse substances and microorganisms used to enhance plant growth. The global market for biostimulants is projected to increase 12 % per year and reach over $2,200 million by 2018. Despite the growing use of biostimulants in agriculture, many in the scientific community consider biostimulants to be lacking peer-reviewed scientific evaluation.
Scope
This article describes the emerging definitions of biostimulants and reviews the literature on five categories of biostimulants: i. microbial inoculants, ii. humic acids, iii. fulvic acids, iv. protein hydrolysates and amino acids, and v. seaweed extracts.
Conclusions
The large number of publications cited for each category of biostimulants demonstrates that there is growing scientific evidence supporting the use of biostimulants as agricultural inputs on diverse plant species. The cited literature also reveals some commonalities in plant responses to different biostimulants, such as increased root growth, enhanced nutrient uptake, and stress tolerance.
Plants can assimilate amino acids from soils. This has been demonstrated in controlled environments and soils of various forest ecosystems. However, the role of root-absorbed amino acids in plant nitrogen nutrition is still poorly understood. We investigated the agroecological performance and nutrient use physiology of two conifers (Abies fraseri and Pinus resinosa) and one hardwood species (hybrid poplar) under amino acid fertilization. Arginine fertilizer (arGrow® Complete) was applied at varying rates (0, 56, 112, 224, and 336 kg N/ha) and compared to an inorganic control treatment (ammonium sulfate 112 kg N/ha). Parameters monitored included tree growth response, foliar nitrogen concentration, and inorganic nitrogen leaching below the rootzone. Results obtained indicate a significant growth and foliar nitrogen response to amino acid treatments, with increasing amino acid application leading to greater growth and foliar nitrogen. However, rates two to three times higher than that of the inorganic control were necessary to provide similar growth and foliar nitrogen responses. These observations were suggested to be due to competition with soil microbes for organic nitrogen, growth inhibition due to the presence of large concentrations of amino acids, or adsorption to cation exchange sites. Amino acid applications did not increase the leaching of inorganic nitrogen due either to the binding of positively charged arginine cations to exchange sites or rapid mineralization followed by plant assimilation. Mineral nitrogen collected in leachate samples increased with the application rate suggesting at least some mineralization in high amino acid application rates. We conclude that growth response and nitrogen use physiology of these species when treated with arginine are largely controlled by soil processes including microbial competition and adsorption. Further studies are being conducted to confirm these hypotheses.
The aim of this research was to evaluate the effects of three new different agricultural bio-stimulants, based on hydrolyzed protein coming from algae (M.A.E.), animal epithelium (A.P.H.), and lucerne origin (H.S.), compared to a control treatment (distilled water) on crop cycle, stem quality and root system growth in L. A. 'Brindisi' soilless cultivation. The bio-stimulants were applied eight times both at foliar and drenching level. The three bio-stimulants gave performances similar among them and higher than the water only according to some of the parameters: the crop cycle came early, the leaves resulted more expanded in the lamina and greener, the flower buds had a higher diameter; the root system showed a higher length development. Finally stem and bulb dry weights values were higher than the control. The bio-stimulant based on animal epithelium differed, from the vegetal and the algae-based ones, in the flower buds number (same values of the control), in the fresh and dry weights of leaves, buds and stem roots (values higher than the control ones). Regarding the cut stem quality if, on the one hand, drenching application method enhanced the stem height, on the other the foliar application increased in the flower buds number. With regard to bulb roots the foliar application method promoted the highest fresh weight value. The A.P.H. with foliar application, compared to the water, advanced both the harvest of nine days.
Tomato plants (cv. 'Belladonna') were grown on the soil in an unheated greenhouse at the farm of Aristotle University of Thessaloniki, Greece. The area of the greenhouse was divided in plots, where 3 levels of pre-planting fertilization were applied: i) conventional, ii) reduced by 20% and iii) reduced by 40%, in 4 replications each. On the day of transplanting, as well as after 4, 6, 8, 10 and 12 weeks Amino16® was applied either in roots or sprayed foliar in 4 combinations (% in roots + % foliar): i) 0 + 0, ii) 0.3 + 0.9, iii) 0.9 + 0.3 and iv) 2.7 + 0. Amino16® is a hydrolyzed protein solution containing 11.3% L-amino acids, 4% total N and 25% organic matter. During cultivation, observations regarding the plant height, node and flower's number as well as the fruit setting were recorded. During harvesting period, each fruit was weighted, observations regarding malformation, insect infestation and fruit cracking were recorded and finally fruits were graded according to the commercial standards in class I, class II or non- marketable. The whole harvesting period of 66 days was divided into two sub-periods: early and normal. The results showed that in conventional fertilization, the application of 0.3% Amino16® in roots + 0.9% foliar increased fruit weight of both class I and class II, as well as of either early or normal period. Under the same treatment, a trend for marketable yield increasing was obvious, although not significant. In reduced by 20% fertilization, the application of 0.3% Amino16® in roots + 0.9% foliar increased marketable yield of early period. On the other hand, in reduced by 40% fertilization, the application of 2.7% Amino16® in roots + 0% foliar increased both total and marketable yield and this was due to the increased fruit number. It could be concluded that the application of amino acids has appreciable effects on the yield of greenhouse tomato and its effective application way (through roots or foliar) dependents on pre-planting fertilization level.
Lettuce plants (cv. 'Simpson') were grown for 10 weeks during winter under greenhouse to investigate the possibility of replacing the supplemental nitrogen (N) fertilization by using Amino16®. Amino16® is a hydrolyzed protein solution containing 11.3% L-amino acids (alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine and valine), 4% total N and 25% organic matter, produced of plant origin raw materials. Three weeks after transplanting, supplemental fertilization with ammonium nitrate or Amino16® was applied. Ammonium nitrate solution was applied to the soil, while Amino16®either to the soil or foliage. Two and 4 weeks later, the foliar application of Amino16® was repeated. Plants without any supplemental fertilization were used as control. The results indicated that crop uniformity was substantially increased when plants received supplemental fertilization with ammonium nitrate and even more when Amino16® was applied to soil. Nutritional quality of lettuce plants, in terms of dry matter, total soluble solid, ascorbic acid and total phenol contents, was not affected by supplemental fertilization either with ammonium nitrate or Amino16®. On the other hand, the application of Amino16® prevented the accumulation of nitrates observed in plants fertilized with ammonium nitrate. Moreover, the foliar application of Amino16® resulted in significant increase of antioxidant capacity, in comparison to the control. According to the above, the use of Amino16® as alternative of inorganic supplemental fertilization is of high importance, in order to improve lettuce crop uniformity, minimize nitrate content in plants, without negative effect on other nutritional components or yield.
Several environmental factors adversely affect plant growth, development and final crop yield, with temperature stress as one of the most limiting variables. Plant thermal acclimation mechanisms include the accumulation of compatible N-rich solutes, such as amino acids, that confer stress tolerance because they act as osmolytes (regulating ion transport and stomatal opening), they have enzyme protecting effect and they influence gene expression and redox homeostasis. This increase of free amino acids naturally originates from hydrolysis of functional proteins or by inhibition of new protein synthesis. However, external applications of amino acids have the advantage of avoiding protein breakdown and saving energy resources. With the aim to assess the effect of exogenous amino acids treatments, several experiments with plants subjected to different stressing temperatures were conducted applying an amino acid product obtained by Enzymatic Hydrolysis (Terra-Sorb® Foliar). In a study in a controlled environment on lettuce plants subjected to three different types of cold stress, treated plants have a higher fresh weight than control plants, exhibiting a higher stomatal conductance which implies productive improvements. Also, heat stress tolerance was evaluated on ryegrass plants (Lolium perenne L.) under several temperatures regimes where lawn physiological and quality parameters were measured. In this case, at a high temperature (36C), ryegrass treated with Terra-Sorb® Foliar shows a superior photosynthetic efficiency (Fv/Fm) and maintains higher levels of chlorophylls and carotenoids. These findings suggest that Terra-Sorb® Foliar has a similar effect to natural plant amino acids and promotes a better more prompt crop recovery from temperature stress.
To determine the most effective chemical. form of foliar nitrogen (N) application for peach trees, we compared various kinds of foliar-applied N and determined N absorption into the leaf. In the first experiment, 15N labeled 50mM solutions were sprayed on to peach leaves in a greenhouse and the amounts of absorbed N were determined using a mass spectrometer. Absorption rates were the highest from urea and sodium nitrate, followed by ammonium chloride and four amino acids, namely L-alanine, L-glutamic acid, glycine and L-lysine, up to 7 days after foliar spraying. The total. amount of foliar-absorbed N showed a similar tendency to the foliar N absorption rate of 3-7 days after foliar spraying. In a subsequent experiment, 15 different amino acids were examined. The rate of foliar N absorption increased as the molecular weights of amino acids decreased. This relationship was not al.ways found and the N absorption rate from arginine and L-lysine was significantly higher compared with other amino acids having the same molecular weights. Based upon these results, urea appeared to be the most effective fertilizer for foliar N application to peach trees compared with other inorganic N sources or amino acids.
Tomato seedlings grown in lime nutrient solution were treated with foliar and root applications of two commercial amino acids products from plant and animal origin. Each product was sprayed 2, 7, 12 and 17 days after transplanting at two different concentrations (1 and 2 ml L-1). For root applications, 0.1 and 0.5 ml L-1 amino acids products were added to lime nutrient solution. Control, untreated plants grown in Fe-sufficient nutrient solution, and untreated lime supplied plants were present as well. Foliar and root application of commercial amino acids product from animal origin led to a severe plant growth depression. On the contrary, shoot and root fresh weights were no affected by addition of plant origin amino acids product for any doses applied. This effect suggests that animal origin product may be phytotoxic at doses used. On the other hand, foliar application of both amino acids products significantly inhibited root Fe(III)-chelate reductase (FCR) activity. As a result of that an important decrease of total Fe concentration and Fe(II) and chlorophyll content was observed in leaves of lime supplied plants. However, the high ratio Fe(II)/Total Fe in plants sprayed with plant origin amino acids product suggests that this treatment increased leaf Fe(III)-chelate reductase activity, specially at the low dose. Statistically differences in total Fe, Fe(II) and chlorophyll contents among untreated lime supplied plants and plants treated with root application of both amino acids products were not found, except to the low dose of plant origin product. That treatment enhanced root FCR activity and leaf total Fe concentration in lime supplied plants. According to these results, neither foliar nor root applications of amino acids were able to counteract lime Fedeficiency symptoms in plants.
Products obtained by hydrolysis of proteins have been recently used as foliar fertilisers in several fruit growing areas. In this study we have assessed the effects of the rate of protein hydrolysis and that of the N concentration in the sprayed solution on the vegetative growth of potted kiwifruit plants. Protein hydrolysates were obtained by enzymatic hydrolysis of "peptone from gelatine". The four fractions obtained (with nominal molecular weights of < 1, 1-3, 3-10 and > 10 kDa), the unhydrolysed peptone and the peptone hydrolysed but not subjected to separation were sprayed at three different concentrations (240, 400 and 800 mg N L-1). Each product was sprayed five times at ten day intervals. Control, untreated, plants and plants treated with urea were present as well. After one month from the first treatment application, the fractions with lowest nominal molecular weights stimulated, especially at lowers rates, shoot growth. The application at highest rate of the fractions with nominal molecular weight 3-10 kDa and > 10 kDa induced shoot growth and biomass increments higher than those caused by urea sprays. The hydrolysed-unfractionated peptone, regardless the rate applied, adversely affected vegetative growth and canopy biomass after two months from the beginning of treatment application, while the unhydrolysed peptone stimulated in the short term vegetative growth when applied at highest rate and performed better than urea. Root growth and biomass linearly increased with the rate of organic N when applied with fraction of 1-3 kDa and > 10 kDa. Data of nitrogen concentrations and content in leaves suggest that vegetative growth effects of the products evaluated are not only due to increase of N nutrition.
The effects of abscisic acid (ABA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on the expression of seven anthocyanin biosynthetic pathway genes in 'Kyoho' grape berries were investigated. In untreated berries, the expression of the UDP-glucose-flavonoid: 3-O-glucosyltransferase (UFGT) gene was detected only at 42 d after full bloom (DAB), whereas the phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone-3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin dioxygenase (LDOX) genes were expressed throughout the growing period. ABA increased anthocyanin content in the skin and the expression of PAL, CHS, CHI, DFR and UFGT genes at 7 d after treatment. In contrast, 2,4-D inhibited the accumulation of anthocyanin and the expression of all the genes examined. The results clearly show that the anthocyanin levels resulting from the application of ABA and 2,4-D were correlated with the expression of anthocyanin biosynthetic pathway genes.
Foliar N fertilization often makes up a major portion of the total N inputs applied to creeping bentgrass (Agrostis stolonifera L.) golf greens. Many such applications are made using fertilizers that have been formulated and marketed as specialty foliar fertilizers. Various forms of inorganic and organic N are included in these specialty products. However, little is currently known about the foliar absorption efficiency among different chemical N forms routinely applied to putting greens. This project was conducted to evaluate the foliar uptake of N from several N-15-labeled inorganic and organic sources. Three common N fertilizer forms {urea (NH2CONH2), ammonium sulfate [(NH4)(2)SO4], and potassium nitrate (KNO3)} were used in the trial along with three amino acids (glycine, L-glutamic acid, and L-proline). All treatments were applied at a rate of 0.5 g N m(-2) on 18 Sept. 2008, 14 Oct. 2008, and 24 June 2010 to plots within a ` Penn G2' creeping bentgrass research green. Plant tissue samples were taken 1 and 8 h after application for N analysis. Foliar uptake of the various N compounds ranged from 31 to 56% of the N applied at the final sampling time of 8 h after application. Nitrogen source had a significant effect on the amount of N fertilizer recovered within plant leaves and shoots. Foliar absorption of KNO3 into aerial plant parts was lower than most of the chemical forms tested while most of the compounds supplied N to the plant in similar proportions.
Heavy metals in sewage sludges accumulate in soils after successive sludge applications and can be toxic to plants, soil organisms, as well as humans and animals along the food chain. Because of this potential threat, many countries have set limits to the additions of metals in sludges to agricultural land, based on (i) the concentrations of metals in sludge itself, (ii) the loading, or total amount, of metal that can be added and often how quickly this can be applied, and (iii) the maximum concentrations of metals in soil which are allowed to build up after sludge applications. This review, based on regulations in the United States and some west European countries, shows that at present three basic approaches to setting limits can be distinguished: (i) a comprehensive analysis of the pathways of pollutant transfer to selected target organisms and an assessment of the likely harmful effects that metals may have on the target; (ii) setting limits consistent with the lowest observed adverse effect concentra...
Diospyros lotus L. is advantageously used as rootstock for Diospyros kaki L. cv. “Rojo Brillante” in most plantations of Eastern Spain. However, one of the few drawbacks of D. lotus L. as rootstock, is the high sensitivity to soil salinity, and specifically chloride, it imparts to the scion, which is visually detected as an extensive late season leaf necrosis. Several complex mixtures of organic polymers such as calcium protein hydrolysates (CPH) have been recommended to counteract salt stress on plants. Nevertheless, the effects of these commercial complex products on tree crops, are not usually rigorously studied, nor satisfactorily explained. The effects on soil and plant of the addition of a commercial CPH in the irrigation water of a D. kaki L. cv. “Rojo Brillante” plantation grafted on D. lotus L. were studied during two successive seasons. Soil salinity and chloride contents, significantly, but slightly, increased in CPH treated subplots, while at the same time leaf chloride contents decreased. These effects suggest a lower chloride plant uptake in CPH treated subplots. The lower chloride uptake in CPH treated trees was accompanied by less leaf necrosis, and also lower leaf water potential. However, the yields of CPH treated and non-treated trees were statistically non-different. The build-up of compatible solutes, mainly proline and glycine betaine, in addition to the biosynthesis of salt-stress-response proteins, which would have been stimulated by the CPH, could explain the observed effects. However, the likely biosynthesis of all these substances may have drawn plant resources from fruit development, thus explaining why yields were the same in treated and non-treated subplots despite the trees in treated subplots showed better adaptation to soil salinity.
In this work, the effects of gibberellic acid, ethylene, 24-epibrassinolide, triacontanol and polyamine (cadaverine, putrescine, spermidine, spermine) pretreatments on the leaf anatomy of radish seedlings grown under saline conditions were studied. Salt stress decreased the stomata number, epidermis cell number and width, leaf thickness and distance between vascular bundles in the varying degrees in the control seedlings non-pretreated with the growth regulators, in comparison with leaves of the ones in
distilled water medium. On the other hand, it was observed that the growth regulator pretreatments affected in different degrees on the leaf anatomy of radish seedlings, and this difference was signifi cant.
Biostimulants are substances which promote plant metabolism and are able to increase yields of various crops. However, their efficiency at field can be affected by climatic conditions. A novel mathematical model based on diffusion transport mechanism is proposed to predict the biostimulant uptake at different climatic conditions. The main input model parameter is experimentally measured effective diffusion coefficient of the biostimulant. The model is applied to a biostimulant prepared from leather waste by enzymatic hydrolysis. Simulations show that climatic conditions have significant impact on biostimulant penetration and should not be neglected in biostimulant application and further research. The suggested model is able to explain observed differences between laboratory and field biostimulant investigations, as well as draw recommendations for protein biostimulant application. The model also shows that the theoretical tools of chemical engineering can be used for optimization of biostimulant performance. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Two cultivars of lettuce plants (Lactuca sativa L. cvs Berlo and Kirsten) were grown for two months in late fall in NFT under three different nitrogen (N)‐regimes but with the same total N concentration (13.4 mM). A reference treatment with a nutrient solution containing 94% nitrate (NO3) and 6% ammonium (NH4) was compared with urea and proteinate treatments in which 20% of the NO3 of the reference treatment was replaced by either of these two N sources. Proteinate is a fertilizer produced in Turkey containing 8% amino acid N and 8% NO3‐N. For both cultivars the fresh weights of the harvested plants were unaffected by the N source as was also the total N uptake. Nitrate content, however, was considerably lower in the urea and proteinate plants, values for the three treatments ranging from 3314 to 4579 mg NO3/kg fresh wt making up from between 44.3% to 55.4% of the total plant N. Of the two cultivars, Berlo accumulated greater concentrations of NO3 than did Kirsten. The accumulation of chloride (Cl) was in the reverse order of that of NO3 with greatest concentrations occurring in the proteinate plants.
Phenolic compounds and total antioxidant capacity of eight leafy vegetables, namely Komatsuna, Mizuna, Pok choi, Mitsuba, Salad spinach, Lettuce, Red amaranth and Green amaranth were determined. The phenolic compounds were characterized as hydroxybenzoic acids, hydroxycinnamic acids and flavonoids. Salicylic acid was, by far, the most common hydroxybenzoic acid, ranging from 4.40 to 117.36 μg/g fresh frozen weight (ffw). Vanilic acid, gallic acid, caffeic acid, chlorogenic acid, p-coumaric acid, ferulic acid and m-coumaric acid were commonly found in all of these vegetables. Isoquercetin and rutin, the most common flavonoids, ranged from 3.70 to 19.26 and 1.60 to 7.89 μg/g ffw, respectively, and hyperoside was highest (38.72 μg/g ffw) in Mizuna. Total antioxidant capacity values varied widely between ABTS+ and DPPH assay methods, with values reported as equivalents to trolox, quercetin and ascorbic acid. Among these vegetables, total antioxidant capacity was found in the following order: Pok choi > Komatsuna > Mizuna > Mitsuba > Red amaranth > Lettuce > Green amaranth > Salad spinach.
Plant-derived protein hydrolysates represent new biostimulant products able to improve crop tolerance to abiotic stresses. The aim of the study was to determine growth, root morphology, SPAD index, chlorophyll fluorescence, leaf mineral composition, and metabolic profiling of greenhouse lettuce either untreated or treated (root or leaf-root application) with a plant-derived protein hydrolysate. For foliar application, plants were sprayed with a solution containing 2.5 ml L −1 of biostimulant, whereas for root application, 100 mL of solution with the same concentration was applied to the growing medium at weekly intervals. Lettuce plants were supplied with two nutrient solutions: non-salt control (1 mM NaCl) or 25 mM NaCl. Salt stress decreased shoot and root dry biomass, SPAD index, chlorophyll fluorescence, leaf mineral composition and increased foliar proline concentration. Root and leaf-root application of the biostimulant increased fresh yield, dry biomass and root dry weight of lettuce under salinity conditions. This was associated with an improvement of plant nitrogen metabolism and an increase of the F v /F m-ratio efficiency in biostimulant-treated plants. Oxidative stress mitigation, increase in osmolytes, changes in sterols and terpenes composition, as well as the less expected increase in glucosinolates were also observed in biostimulant-treated plants grown under saline conditions. The present study proves that the application of plant-derived protein hydrolysate increases plant performance when plants are grown under salinity conditions. The most favorable metabolic profile was obtained when biostimulant was applied to both roots and leaves.
Endive is a leaf vegetable, not commonly known in Poland, although popular in Western and Southern Europe. It deserves attention because of its high nutritive value and bitter taste caused by sesquiterpene lactones. In the experiments carried out in the years 2008–2009 the effect of mineral-organic fertilizers (Goëmar Goteo, Aminoplant) on the yield and quality of curly endive ('Cigal') and escarole ('Excel') was investigated. Seeds were sown in three periods. After four weeks plants were transplanted into the field. Min-eral-organic fertilizers were applied in accordance to the producer's recommendation: the Goëmar Goteo preparation was used twice for seedlings watering while the Aminoplant preparation was used for plants spraying in the second and third week after transplanting them into the field. Mineral-organic fertilizers did not affect the yield of the investigated cultivars. The highest commercial yield of endive and the highest mean weight of leaf ro-sette was obtained for the first term of cultivation. Plants in the third term of cultivation characterized with the highest dry matter content. The least amount of nitrates was cumu-lated in curly endive leaves. The highest content of calcium was observed in the first term of cultivation. The content of potassium and phosphorus was on similar level during the first and the second term of cultivation. The significant effect on the macroelement con-tent due to applied preparations was not observed. The effect of mineral-organic fertilizers on the content of flavonoids was examined. Leaves of endive rosettes treated with mineral-organic fertilizers synthesized rutoside and higher amount of astragalin (3-O--kaempferol glucoside) in comparison with control combination.
Formic, phosphoric and nitric acids were used for hydrolysis of the commercially available hydrolysis product of chrome shavings Hykol-E. The aim of the work was to prepare low-molecular weight product (M(w) < 5000 g.mol(-1)) to be used as the plant bio-stimulator. Course of hydrolysis was monitored by following the changes of molecular weight (MW) and molecular weight distribution (MWD) determined by gel permeation chromatography (GPC). The study demonstrated that MW and MWD of hydrolysates are influenced by the choice of hydrolysing acid, its concentration as well as by the time of acid treatment. Using the combination of enzymatic and acid hydrolysis, it is possible to prepare products with the tailor-made, pre-defined molecular weight fitting the intended use.
The objective of this work was to study the effect of root and foliar application of two commercial products containing amino acids from plant and animal origin on iron (Fe) nutrition of tomato seedlings cultivated in two nutrient media: lime and normal nutrient solutions. In the foliar-application experiment, each product was sprayed with 0.5 and 0.7 mL L–1 2, 7, 12, and 17 d after transplanting. In the root application experiment, 0.1 and 0.2 mL L–1 of amino acids products were added to the nutrient solutions. In both experiments, untreated control plants were included as well. Foliar and root application of the product containing amino acids from animal origin caused severe plant-growth depression and nonpositive effects on Fe nutrition were found. In contrast, the application of the product from plant origin stimulated plant growth. Furthermore, significantly enhanced root and leaf FeIII-chelate reductase activity, chlorophyll concentration, leaf Fe concentration, and FeII : Fe ratio were found in tomato seedlings treated with the product from plant origin, especially when the amino acids were directly applied to the roots. These effects were more evident in plants developed under lime-induced Fe deficiency. The positive results on Fe uptake may be related to the action of glutamic acid, the most abundant amino acid in the formulation of the product from plant origin.
The uptake of phenylalanine and tyrosine into seedling root tips of Cucumis melo and Caesalpinia tinctoria depended on coexisting metabolic and non-metabolic processes. Competitive inhibition studies and kinetic experiments indicated that a single active uptake system operated for all α-amino acids. This active uptake system is compared to those occurring in other types of organism, and the possible role of cation-exchange uptake is discussed. 3-Hydroxymethylphenylalanine and 4-hydroxy-3-hydroxymethylphenylalanine, natural products of Caesalpinia tinctoria, inhibited phenylalanine uptake more in Cucumis than in Caesalpinia.