No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effects of alfalfa leaf extracts and phenolic allelochemicals on early seedling growth and root morphology of alfalfa and barnyard grass
Abstract
Alfalfa (Medicago sativa L.) plants contain water-soluble substances that are autotoxic as well as allelopathic to other plants. Laboratory experimentation through a petri dish assay with imbibed seeds was conducted to evaluate the phytotoxic effects of alfalfa cv. “Vernal” leaf extracts, coumarin, trans-cinnamic acid, o-coumaric acid, and hydro-cinnamic acid on the seedling growth and anatomical responses of 6 day-old alfalfa and barnyard grass. With increasing concentration, the alfalfa leaf extracts significantly reduced root lengths of alfalfa and barnyard grass (Echinochloa crus-galli, Beauv. var. oryzicola Ohwi). Coumarin, trans-cinnamic acid, o-coumaric acid, and hydro-cinnamic acid at 10−4M significantly reduced root lengths of alfalfa and barnyard grass. The root systems, especially root tips of alfalfa, were stunted and swollen by the aqueous alfalfa leaf extracts at 30gl−1 and coumarin at 10−3M. This research suggests that alfalfa plant extracts significantly affected root growth and morphological differentiation of susceptible plants, resulting in reduction of their biomass in the presence of either autotoxic or allelopathic compounds. The results may have value in enabling weed control based on natural plant extracts.
... The study reported by Hedge and Miller demonstrated that the root length and branch number of alfalfa showed a curvilinear decrease with increasing concentration of coumarin [7]. The study of Chon et al. showed that coumarin is the most toxic and abundant autotoxic substance in alfalfa, and that 10 −3 M of coumarin significantly inhibits root growth and interferes with the growth-division process of root epidermal cells in alfalfa [8]. Numerous studies have demonstrated that coumarins can negatively affect plants. ...
... Autotoxicity is one of the main reasons limiting the production and sustainable use of alfalfa [43]. Coumarin is the most abundant and toxic autotoxic substance in alfalfa [8]. Hall et al. found that autotoxic substances can substantially reduce seed germination [44]. ...
... Vaughan et al. found that autotoxic substances inhibited both the primary and secondary roots of plants [63]. Chon et al. showed that coumarin, an autotoxic substance of alfalfa, significantly inhibited elongation growth and cell division in root tip cells [8]. In this study, the root tip count, root volume, mean root diameter, and root surface area of alfalfa seedlings under coumarin treatment were significantly lower than those of the control, which indicated that coumarin could inhibit the root growth and development of alfalfa seedlings, in agreement with the findings of Chon et al. ...
The allelopathic theory has garnered considerable attention in the field of agricultural production for its efficient plant protection, rapid crop yield increase, and scientific establishment of the crop rotation system. To study the effects of the main maize allelochemical DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) on the growth and development of alfalfa under autotoxic coumarin stress, we treated alfalfa seedlings with DIMBOA under coumarin stress and non-stress conditions in this study. Results show that 0.0342 mM coumarin significantly inhibited alfalfa seed germination percentage(Gp), germination potential(GP), radicle length, germ length, seeding height, and simple viability index (SVI), with decreases of 37.29%, 59.91%, 7.60%, 30.90%, 13.27%, and 45.70%, respectively. An amount of 0.6 mM DIMBOA could promote alfalfa seed Gp, GP, radicle length, germ length, seeding height, dry fresh ratio, and SVI, with increases of 12.38%, 23.91%, 48.69%, 48.65%, 48.68%, 295.12%, and 67.17%, respectively. However, the addition of DIMBOA under conditions of coumarin stress could effectively alleviate coumarin effects on alfalfa seedlings. Coumarin + DIMBOA treatment for 24 h mainly decreased reactive oxygen species (ROSs) and malondialdehyde (MDA) as well as soluble protein and soluble sugar, increasing some antioxidant enzyme activities and antioxidant content to alleviate the oxidative damage of alfalfa caused by coumarin stress. Administration of treatment for 72 h significantly promoted the morphological development of alfalfa seeding roots. Administration of treatment for 96 h significantly enhanced the photosynthetic capacity of alfalfa seedlings. The results of principal component analysis demonstrated that chlorophyll b(Chl b)and net photosynthetic rate(Pn) were the key indicators for coumarin + DIMBOA treatment to promote photosynthesis in alfalfa seedlings. Additionally, root length, mean root diameter, and root volume were the key indicators of root growth and development. Coumarin + DIMBOA treatment primarily increased catalase(CAT), peroxidase (POD), and ascorbate peroxidase (APX) activity and antioxidants(ASA) while reducing MDA and superoxide anion radical(O2•−). This study strongly suggested that DIMBOA can effectively improve the tolerance of alfalfa seedlings to coumarin stress through a combination of effects on root morphology, photosynthesis, and physiological indicators.
... In addition, these substances might also influence the microbiome, either by the exuded substances inhibiting pathogens and microorganisms that exhibit negative effects for the seedling [4] or by the substances stimulating beneficial bacteria for the seedling [5][6][7][8] Alfalfa (Medicago sativa L.) plants are known to release various allelopathic substances into the soil [9][10][11][12]. Surprisingly, some of these compounds are autotoxic, which means that the plants themselves are impaired by them [13][14][15]. In the case of alfalfa, the allelochemicals are released either from leaves or from the roots [9,13,[16][17][18] and include saponins and various isoflavonoids, e.g., medicarpin, 4-methoxymedicarpin, sativan and 5-methoxysativan [14,[19][20][21]. ...
... Surprisingly, some of these compounds are autotoxic, which means that the plants themselves are impaired by them [13][14][15]. In the case of alfalfa, the allelochemicals are released either from leaves or from the roots [9,13,[16][17][18] and include saponins and various isoflavonoids, e.g., medicarpin, 4-methoxymedicarpin, sativan and 5-methoxysativan [14,[19][20][21]. ...
Citation: Abouzeid, S.; Beutling, U.; Elekhnawy, E.; Selmar, D. Antibacterial and Antibiofilm Effects of Allelopathic Compounds Identified in Medicago sativa L. Seedling Exudate against Escherichia coli. Molecules 2023, 28, 2645. https:// Abstract: In this study, the allelopathic properties of Medicago sativa L. (alfalfa) seedling exudates on the germination of seeds of various species were investigated. The compounds responsible for the allelopathic effects of alfalfa were identified and characterized by employing liquid chromatography ion mobility high-resolution mass spectrometry. Crude exudates inhibited the germination of seeds of all various plant species tested. Overall, nine compounds in alfalfa were identified and quantified. The most predominant compounds were a hyperoside representing a flavonoid glucoside, the non-proteinogenic amino acid canavanine, and two dipeptides, identified as H-Glu-Tyr-OH and H-Phe-Glu-OH. The latter corresponds to the first finding that dipeptides are exuded from alfalfa seedlings. In addition, the antibacterial and antibiofilm activities of alfalfa exudate and its identified compounds were elucidated. Both hyperoside and canavanine revealed the best antibacterial activity with minimum inhibitory concentration (MIC) values that ranged from 8 to 32 and 32 to 256 µg/mL, respectively. Regarding the antibiofilm action, hyperoside and canavanine caused a decline in the percentage of E. coli isolates that possessed a strong and moderate biofilm-forming potential from 68.42% to 21.05% and 31.58%, respectively. Studies on their inhibiting effects exhibit that these major substances are predominantly responsible for the allelopathic and antimicrobial effects of the crude exudates.
... The autotoxicity of this species is conditioned by the presence of water-soluble phenolic compounds [48]. The strongest autotoxicity is caused by leaf and flower extracts [49]. However, a much weaker effect was observed after using extracts from the roots of older plants or seeds. ...
... However, when the seeds of the studied species were germinated as a mixture, a stimulating effect of the application of M. sativa root extract on the lengths of the leaves was noticed, regardless of the pH of the solution. Studies by other authors [49] indicate that the use of leaf extract at a concentration of 10 g/L inhibits root growth by about 50%, while it has no effect on shoot growth. Only the application of the extract at a concentration of 40 g/L caused the complete inhibition of the growth of both organs. ...
Drought and allelopathic conditions impact the germination of seeds of grass and legume species used in mixtures on grassland. This study evaluated the effects of drought and Medicago sativa root extracts at different pH levels on the germination and characteristics of seedlings of Lolium perenne and selected Medicago species. Two experiments were carried out: the first explored the effects of drought induced by PEG solutions (0.0, −0.3, and −0.6 MPa) under silicon (Si) application; the second studied the influence of Medicago sativa root extracts (12 and 24 g/100 mL H2O) and variable pH solutions (control, 5.0, and 6.5) on seed germination. Germination was carried out on Petri dishes for individual species and in two-species mixtures. The drought conditions did not affect the germination capacity of seeds, but it increased the dry weight of the seedlings of the tested species. The application of silicon decreased the root length of the seedlings of all species, independent of the germination conditions. The higher concentration of M. sativa root extract combined with the studied pH solutions had an inhibitive impact on the germination capacity of L. perenne. Our findings revealed that the lower concentration of M. sativa root extract had a beneficial effect on the morphological features (length of roots and leaves, fresh and dry weight) of the seedlings when germination was carried out separately for both species. In the mixture, the effect was especially marked for L. perenne (only in terms of the root length and fresh weight of seedlings). The applied root extracts in combination with the acidic pH conditions limited the germination capacity and growth of the seedlings of L. perenne the most when germination was performed separately. It was concluded from this study that silicon application did not improve the germination capacity of seeds under drought conditions, whereas the germination of L. perenne seeds in a mixture with M. sativa mitigated the negative allelopathic effects of M. sativa root extracts on the seed germination capacity and morphological features of seedlings of L. perenne.
... Some crops synthesize allelopathic chemicals, which can contribute to yield losses under monocropping (Huang et al., 2013). Such crops with autotoxicity include alfalfa (Chon et al., 2002;Miller et al., 1988), canola (Yasumoto et al., 2011), and wheat (Lodhi et al., 1987;Wu et al., 2001Wu et al., , 2007. Crops with autotoxicity can also affect the growth of different plants because of their allelopathic compounds, including that of subsequent crops (e.g., Asaduzzaman et al., 2015;Yasumoto et al., 2011). ...
... Autotoxicity of canola (Yasumoto et al., 2011) was apparent in that canola did no grow well in self-cultivated soils. However, this was not the case for autotoxicity of alfalfa (Chon et al., 2002;Miller et al., 1988) and wheat (Lodhi et al., 1987;Wu et al., 2001Wu et al., , 2007. Thus, degrees of autotoxicity appeared to be crop specific, but it is possible that the observed varying autotoxicity was due to the specific cultivars used in this study (Chung & Miller, 1995;Wu et al., 1999Wu et al., , 2000. ...
Plant–soil feedback (PSF) can be a major driver of plant performance in communities, and this concept can be used in selecting crop rotation sequences to maximize agricultural yields. Potential benefits of using PSF in this context include nutrient use optimization, pathogen reduction and enhancement of mutualisms between crops and microbes. Yet, the contributions of these combined mechanisms are poorly understood. Here we investigated the relative contributions of these mechanisms using five major crops commonly cultivated in rotation (alfalfa, canola, maize, soybean and wheat) under controlled conditions. We trained soil by growing each of the five crops in a ‘training phase’, and then reciprocally planted the five crops in the trained soils in a ‘feedback phase’. To tease out soil biota from nutrient effects, we established three treatments: ‘control’ (trained unsterilized soil used in the feedback phases), ‘biota’ (sterilized soil in the feedback phase inoculated with soil biota from the ‘control’ treatment after the training phase), and ‘nutrient’ (sterilized soils in both phases). Plant–soil feedback for each crop was calculated by comparing the total biomass of each crop grown in soils trained by each of the four other crops (i.e., in rotation) against total biomass in self‐trained soil (i.e., monocropping). We found that PSF values varied among crop combinations in all the treatments, but such variation was the greatest in the ‘nutrient’ treatment. Overall, soil ‘biota’ feedback tended to be lower whereas ‘nutrient’ feedback tended to be greater compared to the unsterilized ‘control’ soil, suggesting that effects of antagonistic biota outweighed those of beneficial microbes in the ‘biota’ treatment, and that plants optimized nutrient uptake when the soil microbiome was absent in the ‘nutrient’ treatment. Furthermore, soils in the ‘nutrient’ treatment trained by the legume crops (alfalfa and soybean) tended to provide the greatest positive feedback, emphasizing the important legacy of N2‐fixers in crop rotation. Taken together, our data demonstrate how nutrients and soil biota can be integral to PSFs among crops, and that assessing PSFs under controlled conditions can serve as a basis to determine the most productive crop rotation sequences prior to field testing.
... The root growth of the alfalfa seedlings of 3105C was mainly affected by the inhibition of radicle length, but the root growth of WL656HQ was only inhibited at high concentrations (S3, S4 and S5). Alfalfa plant extracts significantly affected root growth and morphological differentiation of susceptible plants [39]. ...
... Alfalfa continuously releases certain secondary metabolites, which enters the soil via self-secretion, aboveground leaching, and residue decomposition. These metabolites directly or indirectly inhibit seed germination, seedling radicle germination, and seedling growth [11], resulting in low seed germination rates, poor seedling growth, and sharp declines in yield and quality in the presence of either autotoxic or allelopathic compounds [39]. A previous study showed that alfalfa plant extracts significantly affected root growth and the morphological differentiation of susceptible plants, resulting in reductions in biomass. ...
Alfalfa (Medicago sativa) is a highly valuable perennial forage legume that suffers from autotoxicity, which decreases plant resistance, reduces soil fertility, causes serious soil-borne diseases, and promotes ecological imbalance. We evaluated the effects of autotoxicity on the seed germination of 22 alfalfa varieties, and then elucidated the oxidative damage and lipid peroxidation in two alfalfa varieties with contrasting autotoxicity tolerances. The technique for order of preference by similarity to ideal solution (TOPSIS) method was used to rank the germination of the 22 alfalfa varieties when exposed to six autotoxic concentrations (0, 0.025, 0.075, 0.125, 0.175, and 0.225 g∙mL−1). We found WL656HQ and 3105C to be autotoxicity-tolerant and autotoxicity-sensitive varieties, respectively. The germination index mainly affects the comprehensive allelopathic index of WL656HQ and 3105C, which were the simple vigor index and radicle length according to the random forest model, respectively. 3105C eliminates reactive oxygen species (ROS) via antioxidant enzymes and antioxidants under T1 (0.025 g∙mL−1), but the oxidative stress system and the oxidative scavenging system cannot maintain the balance under T2 (0.125 g∙mL−1), causing oxidative bursts. In comparison, WL656HQ used its oxidative scavenging system (peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR)) to maintain its redox dynamic balance by removing excess ROS at all concentrations. In conclusion, the positive and negative indicators of autotoxicity for the two varieties were ascorbate (ASA) and hydroxyl free radicals (OH•), and proline (Pro) and dehydroascrobate (DHA), respectively. The most sensitive autotoxic concentrations of 3105C and WL656HQ were T2 (0.125 g∙mL−1) and T1 (0.025 g∙mL−1), respectively.
... Similarly, Jacob and Nair (1999) reported inhibitory effect of Casuarina leaf extracts on germination, plumule and radicle growth in rice and cowpea. This reduction in seedling growth and biomass may be due to imbalances in water uptake or osmotic balances of the tissues because of allelochemical toxicity (Blum et al., 1999) and or root growth inhibition (Chon et al., 2002). Chon et al. (2002) mentioned that some plants root tip growth nearly inhibited to escape from allelochemicals absorption. ...
... This reduction in seedling growth and biomass may be due to imbalances in water uptake or osmotic balances of the tissues because of allelochemical toxicity (Blum et al., 1999) and or root growth inhibition (Chon et al., 2002). Chon et al. (2002) mentioned that some plants root tip growth nearly inhibited to escape from allelochemicals absorption. Nevertheless, Sing et al., (2003) found that aqueous leaf leachates of Eucalyptus citriodora inhibited seed germination and seedling growth of Vigna Species and elongation of plumule more suppressed than radicles. ...
Leaf extracts of Casuarina. equisetifolia L. was evaluated for its allelopathic influenced on rice cultivars viz. IR- 20 and TKM – 9. Leaf extracts was tested at 2.5, 5, 10, 15 and 20% concentration. Seed germination, shoot length, biomass, chl - a , chl- b, carotenoids, starch, protein and amino acid contents were significantly reduced by leaf extracts and highest inhibition was observed in 20% concentration. But at lower concentration (2.5%), the seedling growth was slightly enhanced than control. The higher degree of germination and growth inhibition was observed in cultivar TKM-9 than IR-20.
... Roots are more sensitive to the phenolic acid reaction than aerial parts of plants (Chon et al. 2002). In this study, we found that FA, CA, and PA had greater inhibitory effects on root biomass than that on aboveground biomass ( Fig. 2C,D). ...
... In this study, we found that FA, CA, and PA had greater inhibitory effects on root biomass than that on aboveground biomass ( Fig. 2C,D). This result is similar to the results of previous studies (Chon et al. 2002, Khattak et al. 2015. At the same time, this inhibitory effect also increased with increasing phenolic concentration (see Djurdjevic et al. 2004). ...
The effects of different concentrations of ferulic acid, chlorogenic acid, and protocatechuic acid were studied in a pot experiment to assess the response of Rhododendron delavayi seedlings. The results showed that three kinds of phenols promoted increases in chlorophyll (Chl) a, Chl b, total Chl, and carotenoid contents, but inhibited the accumulation of biomass. Low concentrations of ferulic acid significantly inhibited stomatal opening, the stomatal opening ratio, stomatal length and width. Chlorogenic acid and the moderate and high concentrations of ferulic acid also significantly inhibited stomatal density. Ferulic acid significantly inhibited net photosynthetic rate and stomatal conductance in seedlings, whereas chlorogenic acid significantly inhibited stomatal conductance. The low and moderate concentrations of chlorogenic acid significantly inhibited transpiration rate, and high concentrations of ferulic acid significantly inhibited the stomatal limitation value. The moderate concentration of protocatechuic acid significantly inhibited net photosynthetic rate and stomatal conductance. Ferulic acid exhibited a greater toxic effect than that of chlorogenic acid and protocatechuic acid for R. delavayi seedlings.
... Notably, the highest concentration of phenolic compounds was found in the leaves, which also exhibited the highest phytotoxic activity, as reported by Mangao et al. (2020). This is consistent with previous studies on alfafa plants, which have identified phenolic compounds as the primary phytochemicals (Chon et al., 2002). Moreover, Liu et al. (2017) demonstrated that aqueous extracts of Juniperus rigida litter, which contained phenolic compounds, inhibited seed germination and seedling growth of Pinus tabuliformis. ...
Cassava, a major carbohydrate source for human consumption, generates significant residues during the harvesting process, including cassava (Manihot esculenta L.) leaves known to exhibit phytotoxicity. However, the water-soluble herbicidal compounds from cassava have not yet been identified. Therefore, this study aimed to identify the responsible phytotoxic compounds in cassava leaves. Phytochemical tests were conducted on aqueous cassava leaf extracts and solvents separated fractions, then phytotoxic compounds were analyzed by Liquid Chromatography Mass Spectrometry (LCMS) to determine their phytotoxic effects. Germination and growth on weeds of Eleusine indica, Ageratum conyzoides, Cyperus distans, and aerobic rice (Oryza sativa) were examined at 0.05% (w/v) in a laboratory assay. Results showed that the degree of phytotoxic activity of various fraction solvents can be listed in the order of decreasing inhibition: ethyl aceta-te>methanol>hexane>water. Five possible herbicidal compounds, including coniferol, transferuladehyde, luteolin, gigantol, and anemonin were identified from cassava leaf ethyl acetate extracts. These findings suggest that cassava leaves may be utilised as novel herbicidal agents for weed control in aerobic rice cultivation.
... In terms of autotoxicity, the allelochemicals are also called autochemicals or phytotoxins 35 . At present, research on autotoxicity mostly focuses on continuous cropping obstacles and plantation decline [36][37][38][39][40] . However, the autotoxicity of invasive species has rarely been studied. ...
Ambrosia artemisiifolia and Ambrosia trifida are annual invasive plants that cause serious harm to agriculture, animal husbandry, and human health. Based on the important characteristic of high-density, cluster distribution of their populations, it is speculated that its autotoxins have an effect on density regulation. This study explored the regulation of autotoxicity on intraspecific density. We used water extracts from two plants to compare and verify the autotoxicity of seed germination, analysed the components of autotoxins. The results showed that A. artemisiifolia and A. trifida had significant autotoxicity, and the highest inhibition rates on seed germination were 27.21% and 77.94%, respectively; ultra-performance liquid chromatography tandem mass spectrometry analysis revealed that chlorogenic acid, caffeic acid, p-coumaric acid, and vanillin were the main autotoxins of the two plants. After the seeds were washed with water, the germination recovery rate of seeds increased with the increased of inhibition degree of autotoxins treatment. Therefore, this study verified the autotoxicity of A. artemisiifolia and A. trifida, which can promote and inhibit the seed germination of A. artemisiifolia and A. trifida to regulate intraspecific competition.
... However, numerous other factors have been identified as inhibitors of lateral root formation and growth, including phytohormones (Fukaki and Tasaka 2009; Shkolnik-Inbar and Bar-Zvi 2010; Lewis et al. 2011). In the specific context of a mixed-grown treatment, shoot and root extracts of some species, generally grass and crops, can have an allelopathic effect on lateral root formation and length in neighbours (Horsley 1977;Pardales et al. 1992;Chon et al. 2002;Amoo et al. 2008;Hossain et al. 2016). Ahmed et al. (2007) reported such an inhibitory effect was much more pronounced in root and lateral root development than for shoot or seed germination. ...
Oak regeneration is jeopardized by purple moor grass, a well-known competitive perennial grass in the temperate forests of Western Europe. Belowground interactions regarding resource acquisition and interference have been demonstrated and have led to new questions about the negative impact of purple moor grass on ectomycorrhizal colonization.
The objective was to examine the effects of moor grass on root system size and ectomycorrhization rate of oak seedlings as well as consequences on nitrogen content in oak and soil.
Oak seedlings and moor grass tufts were planted together or separately in pots under semi-controlled conditions (irrigated and natural light) and harvested one year after planting. Biomass, N content in shoot and root in oak and moor grass as well as number of lateral roots and ectomycorrhizal rate in oak were measured.
Biomass in both oak shoot and root was reduced when planting with moor grass. Concurrently, oak lateral roots number and ectomycorrhization rate decreased, along with a reduction in N content in mixed-grown oak.
An interference mechanism of moor grass is affecting oak seedlings performance through reduction in oak lateral roots number and its ectomycorrhization, observed in conjunction with a lower growth and N content in oak. By altering both oak roots and mycorrhizas, moor grass appears to be a species with a high allelopathic potential. More broadly, these results show the complexity of interspecific interactions that involve various ecological processes involving the soil microbial community and need to be explored in situ.
... The higher phytotoxic impact may be due to the direct interaction of allelochemicals and disruption of metabolic processes in the growing regions of the root (15). The root growth reduction due to allelochemical stress limits the water absorption, resulting in a shorter seedlings length (12). Allelochemicals slows down the respiration, mitochondrial activity and ATP production, thus, affecting cellular biochemical processes (7). ...
The allelopathic potential of Calotropis procera (Aiton) W.T. Aiton was investigated on germination, growth and mineral uptake of five Agricultural cash crops, including gram (Cicer arietinum L.), tomato (Solanum lycopersicum L., mungbean [Vigna radiata (L.) Wilczek], fenugreek (Trigonella foenum-graecum L.) and lettuce (Lactuca sativa L.). For this purpose, we treated seeds with 0 %, 10 %, 20 % and 30 % concentrations of the entire plant aqueous extract. The effect on germination was examined for six days, while the root and shoot length of the seedling were measured after 10 days of growth. The germination parameters, including germination percentage and mean germination time (MGT), were recorded at each concentration, including control. The results showed that these parameters except MGT were significantly reduced at higher concentrations. Likewise, biomass, mineral uptake and chlorophyll contents were markedly reduced. With the extract treatment, the fungal species (i.e. Fusarium solani, Macrophomina phasiolina, Sclerotinia sclerotium, Fusarium semitectum, Phompsos sp., Lasiodiplodia theobromae and Rhizoctonia solani) exhibited prominent inhibition effects with the methanolic and to a much lesser extent by the aqueous extract respectively. Allelochemicals like p-hydroxybenzoic acid, coumaric acid, syringic acid, ferulic acid, quercetin and caffeic acid were identified using HPLC and showed their antifungal activities. These results suggested that C. procera is harmful to crops under field conditions, but its extract may be used as a fungicide to control pathogenic fungi.
... In terms of autotoxicity, the allelochemicals are also called autochemicals or phytotoxins 34 . At present, research on autotoxicity mostly focuses on continuous cropping obstacles and plantation decline [35][36][37][38][39] . However, the autotoxicity of invasive species has rarely been studied. ...
Ambrosia artemisiifolia and Ambrosia trifida are annual invasive plants that cause serious harm to agriculture, animal husbandry, and human health. Based on the important characteristic of high-density, cluster distribution of their populations, it is speculated that its autotoxins have an effect on density regulation. This study explored the regulation of autotoxicity on intra-species density. We used water extracts from two plants to compare and verify the autotoxicity of seed germination, analysed the components of autotoxins. The results showed that A. artemisiifolia and A. trifida had significant autotoxicity, and the highest inhibition rates on seed germination were 27.21% and 77.94%, respectively; Ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS) analysis revealed that chlorogenic acid, caffeic acid, p -coumaric acid, and vanillin were the main autotoxins of the two plants. After the seeds were washed with water, the germination recovere rate of seeds increased with the increased of inhibition degree of autotoxins treatment. Therefore, this study verified the autotoxicity of A. artemisiifolia and A. trifida , which can promote and inhibit the seed germination of A. artemisiifolia and A. trifida to regulate intra-specific competition.
... It has been documented that aqueous extracts of alfalfa leaf provided complete inhibition of barnyard grass at 0.4% concentration. Similar to the alfalfa leaf extracts, it is suggested that cassava leaf extracts contain allelochemicals which could induce the appearance of abnormal seedlings (Chon et al. 2002). In contrast, the shoot growth of E. indica seedlings was stimulated after treatment of leaf extracts at 0.06% and 0.125% concentrations (Figure 4(B)-4(C)). ...
Weed infestation is a major problem in the aerobic rice system due to the lack of standing water that could prevent the growth of weeds. To reduce heavy reliance on herbicide, this research aims to determine the potential of cassava allelopathy for inhibition of weeds in aerobic rice. The allelopathic potential of cassava extracts on the germination and growth of tested weed species (Eleusine indica, Ageratum conyzoides, and Cyperus distans) and aerobic rice (Oryza sativa) was conducted in the laboratory. The results showed that increasing the aqueous extract concentrations of cassava extracts inhibited the germination and seedling growth of tested weeds, suggesting the allelopathic effects of cassava extracts are concentration dependent. The degree of phytotoxicity of different vegetative parts of cassava can be classified in order of decreasing inhibition as follows: leaf, stem, tuber, and tuber peel. Aqueous leaf extract of cassava at a concentration of 0.5% (w/v) provided complete inhibition on A. conyzoides, E. indica, and C. distansgermination whereas 25% to 100% inhibition on the shoot growth was recorded. By contrast, the shoot growth and germination of aerobic rice were not affected. These results suggest that the cassava leaf extracts contain water-soluble allelochemicals for inhibition on A. conyzoides, E. indica, and C. distans in aerobic rice.
... A lonquimay seulement, la culture de luzerne se maintient dans le temps. Outre les conditions de sol plus favorables aux légumineuses dans cette région (pH plus élevé, absence du ravageur H. obscurus), on peut avancer que la luzerne, de par ses propriétés allélopathiques, est très compétitives face aux autres espèces (Chon et al. (2002). ...
Cette thèse démontre l'existence de l'agriculture comme une activité importante du peuple mapuche à travers l'histoire, depuis la conquête jusqu'au XXIème siècle. La recherche démontre la capacité des mapuche pour résister et combattre des ennemis puissants et féroces, et également l'intelligente adaptation à toutes les invasions étrangères, même celles de l'Etat Chilien.La thèse montre les changements dans l'agriculture et la capacité du peuple mapuche pour innover, depuis l'invasion des incas au XVème siècle, la conquête des espagnols du XVIème au XIXème siècle et l'occupation chilienne jusqu'au XXIème siècle. Au moment de la conquête espagnole, les mapuche étaient un peuple en pleine sédentarisation qui occupait un territoire de façon autonome. Les communautés peuplaient des terrains délimités et pratiquaient une agriculture de subsistance culturelle, en plus de la cueillette, de la pêche et de la chasse. La société était organisée en groupes de lignées matricielles, ils avaient une cosmovision, une culture et une organisation sociale. Pendant la colonie, ils adoptent et s'approprient les technologies européennes, ils développent un élevage puissant qui s'étend à la pampa argentine. Cette activité génère un échange commercial puissant et diversifié entre le territoire mapuche et le Royaume du Chili, fait de produits animaux, d'objets manufacturés et de produits alimentaires. L'échange était défavorable aux mapuche et dut être régulé par des traités. La République commence à reconnaitre les territoires mapuche, mais ensuite, pour des raisons d'expansion économique, elle les envahit à feu et à sang. Les mapuche résistent mais sont mis en déroute par l'armée chilienne, qui a gagné la guerre du Pacifique.Les mapuche commencent le XXème siècle spoliés de 95% de leurs terres, de presque tout leur puissant élevage, de leurs biens capitaux, des machines, des équipements, des charrues, des semences et des plantations. Mais surtout ils sont exclus, mis en ségrégation et confrontés à des stratégies d'assimilation et d'extermination. Ils meurent d'inanition, de maladies et d'épidémies. C'est là qu'est générée la vraie dette historique de l'Etat du Chili envers les mapuche. Les Réformes Agraires, et particulièrement celles de l'Unité Populaire (1970-1973) soulèvent le problème des terres usurpées, elles proposent et mettent en œuvre des solutions, que la dictature militaire (1973-1990) annule. La Concertation pour la Démocratie (1990-2010) reconnait les spécificités du peuple mapuche et résout une partie des conflits pour la terre. Actuellement, les mapuche de la campagne sont confrontés à de puissantes stratégies d'assimilation et d'extermination de leur culture, cependant au niveau des communautés rurales, on observe la capacité manifeste du peuple mapuche de s'adapter aux changements, résister et imposer les termes de base des conditions nécessaires pour se reconstruire comme peuple originaire du Chili.
... ;Singh and Sahu, 2010;Singh et. al., 2011;Singh and Sahu, 2012;Singh, 2015 andKamilya, 2020). Secondary metabolites apparently act as defense (against herbivores, microbes, viruses, or competing plants) and signal compounds (to attract pollinating or seeddispersing animals), as well as protecting the plant from several biotic and abiotic stressors (Chon et. al., 2002;Tegelberg et. 2004) from the beginning of their life cycle. Studies on Australian Proteaceae (Hanley and Lamont, 2002) provide evidence that high leaf phenolic contents and antioxidants deter herbivores as well as abiotic stressors. These phenolic compounds as well as other primary or secondary metabolites may have highly diverse biologi ...
Seedlings of eight weeds and seven crops are described and quantitatively analyzed with six chemical parameters viz. leaf extract pH, ascorbic acid contents, total chlorophyll content, protein content, total phenolic content and peroxidase activity. Morphological traits of seedlings of both crops and weeds are used for the preparation of artificial keys separately for their proper identification. Of many chemical parameters, only these six parameters may address towards better adaptation of weeds and crops to the stressful environment. However, very little differences have been resulted in the above chemical parameters under numerical analysis through ANOVA and Principal component analysis.
... The high concentration of aqueous extracts treatment (100%) showed a significant effect on the germination percentage of wheat, Zea mays, and Leucaena , but Maize was found comparatively tolerant to aqueous extracts of Artemisia than the other seeds and this may be due to more resistance mechanisms that have been evolved in this plant. Chon et al. (2002) [41] mentioned that the growth of root tip of some plants nearly inhibited to escape from allelochemicals absorption. The aqueous extract of both species at the concentration of 50 and 75% caused a significant decrease in the lengths of radical and plumule of the seedling in comparison with that of 25% and control. ...
The essential oils from the aerial parts of Artemisia herba alba and A. Judica growing wild in Tabuk region at North of Saudi and Saint Catherine analyzed by GC-MS analysis. The goal was to study the effect of different environmental conditions on the content of total phenolics and on the chemical composition of essential oils of two species of Artemisia, as adaptability indicator to prove that the plants may react with environmental stresses by the production of these compounds, which is reflected on the potency of its allelopathic effect as a competitive strategy of these species. The present research indicated that the total phenolic contents and chemical composition of essential oils of both species of Artemisia are influenced by the difference in the environmental conditions and the geographic location, which resulted in a difference in the potency of allelopathic activity of Artemisia extracts. The allelopathic effects of aqueous and oil extracts of both species of Artemisia on the germination of wheat (Triticum aestivum L.), maize (Zea mays L.) and Leucaena leucocephala seeds were studied. Higher extracts of both species showed maximum inhibition on the germination of the tested seeds in comparison with a control. In the present research, we have found that all oil extracts at the concentrations of 3 and 5µl/ml inhibited seed germination of wheat and Leucaena , as well as seedling growth (significant inhibition of radicle and plumule elongation of both species). Maize was found comparatively tolerant to aqueous extracts of Artemisia than wheat and leucaena. A.judica exhibited greater phytotoxicity than A.herba alba. It can be suggested that the essential oils and aqueous extracts of both species of Artemisia have the potential to be used as a natural herbicide and their allelopathic activity was significantly affected by environmental conditions.
... Vascular tissue and metaxylem area showed a complex behavior as it increased in few cases, but decreased in others when the allelochemical extract of A. scholaris was applied. Increased vascular bundle along with broader metaxylem vessels positively correlated with water movement through roots (Chon et al., 2002). Wheat lines that showed increased vascular tissue can survive better under stressful conditions (Donaldson, 2001) Pith parenchyma along with cortical parenchyma are water storing tissues in roots (Pereira at al., 2017). ...
... Phenolic acids are of great importance in allelopathy [19][20][21]. Phenolic acids such ascaffeic acid, transcinnamic acid, hydrocinnamic acid, coumarin, ferulic acid, m-coumaric acid, o-coumaric acid and p-coumaric acid are the main groups of phytotoxic substances associated with alfalfa allelopathy [21][22][23]. ...
This study aimed at evaluating the allelopathic effects ofalfalfa residues on the germination and growth of the barley plant grains treated with different concentrations (6gm, 9gm, 12gm) of alfalfa residues. Results of this study showed that the percentage of germination significantly decreased when treated with different concentrations of alfalfa plant residues compared to the control. The concentration of 12gm led to the highest significant decrease. Barley seedlings germination percentage was decreased significantly with a rate that fluctuates between 26.7%-60% during the first week of seedling emergence compared to the control. Also, the lowest significant decrease (p <0.05) was recorded in the length of the foliage (12.67 cm in length in the first sample and 16.33 cm in the second sample), poxes (4.5 cm in length in the first sample and 4.67 cm in the second sample) and the whole plant (17.17 cm in length in the first sample and 21.0 cm in length in the second vessel) at a concentration of 12g compared to the control. In the case of weights, the concentration of 12g recorded the least significant difference (p <0.05) in the first sample (with a weight of 0.22 g), while in the second sample the concentration of 9g recorded the lowest significant difference (p<0.05) for the whole plant (0.25gm weight) compared with the control, while no significant differences were recorded in the difference in the time of sampling. Further investigations are needed to determine the influence of this variations, and to identify the active compounds involved in alfalfa residues allelopathy.
... Biomass of root and shoot are also affected by different concentrations of aqueous leaf extracts. Biomass loss can attribute the water and nutrient uptake ability of plants (Chon et al., 2002) which hamper the normal growth and establishment of a plant. Sahoo et al. (2007) suggested that aqueous leaf extracts of two tree species showed a reduction of the fresh and dry weight of maize. ...
Background: Agroforestry might be a better strategy for sustainable land use and crop production. Allelopathic effect of Streblus asper Lour. (Moraceae) an agroforestry tree species was documented on chickpea (Cicer arietinum L.) seed germination and seedling growth.
Methods: The present study was conducted to evaluate the allelopathic potentialities of different concentrations (0.125%, 0.25%, 0.5%, 1.0%, 2.5% and 5%) of aqueous leaf extracts of S. asper on seed germination and seedling growth in laboratory based experiments. The allelopathic potentialities were studied based on seed germination, germination rate, root length, shoot length, biomass, seed vigor index etc.
Result: The inhibitory effect was more pronounced with the increasing concentrations of aqueous extracts. 5% aqueous leaf extracts showed a maximum inhibitory effect on seed germination, root length, shoot length, dry weight of root and shoot as compared to control. Based on the allelopathic index, concentrations of 5% aqueous extract showed a strong inhibitory effect. Aqueous leaf extracts contain water-soluble allelochemicals which affect the seed germination and seedling growth. The inhibitory allelopathic effect can be taken as serious consideration before plantation of chickpea in an association of this tree species because of its inhibitory effect on seed germination and early stages of development.
... Because of its strong activities and its wide applications, the synthesis and application of vanillic acid and its derivatives have attracted much attention [10][11][12][13][14][15]. We still focused on the synthesis and antibacterial activities of preservatives. ...
C11H12O5, orthorhombic, P212121 (no. 19), a = 5.5523(7) Å, b = 12.7610(17) Å, c = 15.374(2) Å, V = 1089.3(2) Å3, Z = 4, R
gt(F) = 0.0273, wR
ref(F
2) = 0.0787, T = 296(2) K.
... As shown in Fig. 1 and Table 1, the results of the current study indicated that both isoscopoletin and umbelliferone inhibited the shoot and root length of the M. pigra seedlings. As revealed in a previous report, isoscopoletin and umbelliferone at the same concentration (1,000 mM) inhibited the germination of Echinochloa crus-galli and Amaranthus retroflexus, respectively (Chon et al., 2002). The coumarin derivatives at 1,000 mM strongly inhibited the growth of Avena roots Goodwin and Taves (1950). ...
Mimosa pigra L. (Fabaceae), commonly known as giant mimosa, is one of the major invasive species, constituting a serious threat to agricultural crops and other plants in the biodiversity. With this study, we aimed to investigate the mechanism underlying the effects on plant growth and development upon exposure to two coumarins. Protein solutions were obtained from giant mimosa seedlings that had been exposed to the coumarins, and they were analyzed with the shotgun proteomic method by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The proteins were identified in seedlings treated with coumarins. The control plants expressed 621 proteins, the plants treated with isoscopoletin expressed 613 proteins, and the plants treated with umbelliferone expressed 640 proteins. The classification of proteins by PANTHER software found that the coumarins interfered with proteins involved in cellular component organization or biogenesis and metabolic processes. STITCH analysis of protein expression after treatment with coumarins confirmed that CUL4, ESF, LNG2 and SCD2 played a role in plant growth and development. WAK1 and WAT1 were involved in cell wall and cell surface responses. At3g61030 and CIP111 were related to Ca²⁺ accumulation and CAND1, CUL4 and ML5 were linked with programmed cell death. It is worthwhile to mention that coumarins increased morphological changes in the epidermis, Ca²⁺ accumulation in the roots and protein expression in plant growth and development, morphological changes, Ca²⁺ accumulation as well as in programmed cell death.
... Some mechanisms of allelopathic activities are similar to plant hormones. Allelopathic compounds through having an impact on root growth can reduce water absorption in plants and thereby reduce the length of seedling [44]. Decreased seedlings length of plant which are exposed to allelopathic compounds may be due to the negative effect of the extract on cell division or cell elongation, which in addition to longitudinal growth of the plant, inhibiting substances in extract can have a negative impact on weight of plant [45]. ...
The present study focused on effects of Trifolium alexandrium L. extract (0.002, 0.004 and control) which is a fast-growing plant on germination, growth and nutrients uptake of medicinal plant Peganum harmala L. Results revealed that T. alexandrium extract had significant (P<0.01).effect on seed germination of P. harmala The maximum (54%) and minimum (28%) seed germination were observed at 0.002 and 0.004 treatments, respectively. The highest radical (11.27 mm) and pedicle (19.10 mm) lengths were obtained in the 0.002 treatment, and the minimum radical (4.05 mm) and pedicle (9.40 mm) length were related to 0.004 treatment. With increased extract concentration, dry weight of P. harmala decreased. Also, the maximum (15.79 mg g-1 fresh weight) and minimum (6.94 mg g-1 fresh weight) chlorophyll contents of P. harmala were observed at 0.002 and control treatments, respectively. The highest (6.08 mg g-1 fresh weight) and lowest (4.34 mg g-1 fresh weight) chlorophyll b and also the highest (4.89 mg g-1 fresh weight) and lowest (2.69 mg g-1 fresh weight) carotenoids contents were obtained in 0.002 and 0.004 treatments, respectively. Furthermore, T. alexandrinum extract had significant effects on the uptake of N, P, K, Zn and Mn. The maximum amount of N uptake (3.77%) was observed in the extract concentration of 0.002. The maximum (0.3%) and minimum (0.21%) P uptake was observed in the control and 0.004 treatments, respectively. With increasing the extract concentration K uptake was decreased. The maximum (0.22 and 0.19%, respectively) and minimum (0.14 and 0.15%, respectively) Zn and Mn uptake were observed in the control and 0.004 treatments, respectively. In general, results showed that high concentration of T. alexandrium extract has deterrent effects on seed germination and growth of P. harmala, so that lower concentration of extract, showed positive effect on seed germination plant growth.
... Root and shoot length are widely used as growth indicators because they are important agronomic features that can easily be influenced by environmental stresses (Li et al. 2010). For instance, root growth is characterized by high metabolism and is therefore very sensitive to environmental changes, such as increases in soil allelochemicals (Chon et al. 2002). Similarly, toxic chemicals may alter plant water potential, which can hinder mineral and ion uptake thereby reducing fresh biomass (Weir et al. 2004). ...
Allelochemicals released by exotic plants can affect neighboring plants. In this study, we examined the effects of leachate extracted from shoots of an invasive clonal plant (Wedelia trilobata) on its own growth and performance, and that of its native congener (W. chinensis). Leachate from W. trilobata was prepared at concentrations of 0, 50, 75, and 100% and was applied to both Wedelia species (which were grown in mono and mixed culture). We monitored the effects of the leachate on plant growth, physiological traits, and relative competition intensity (RCI) in each species. Leachate concentration significantly affected the majority of growth and physiological traits in both species. Higher leachate concentrations significantly increased most traits of W. trilobata under mono and mixed culture. In contrast, many growth and physiological parameters in W. chinensis were significantly reduced in response to higher concentrations of leachate. Growth and physiological traits were higher in W. trilobata than W. chinensis at higher leachate concentrations in both mono and mixed culture. In W. trilobata, RCI significantly increased with increasing leachate concentration. However, RCI in W. chinensis remained consistently low in response to higher leachate concentrations. Overall, the addition of leachate from invasive W. trilobata had a strong allelopathic effect on native W. chinensis under mono and mixed culture. Conversely, growth and competitive ability in W. trilobata was enhanced in response to the leachate. Thus, allelochemicals from W. trilo-bata promote its own performance while simultaneously suppressing that of a native congener, which has likely contributed to its invasion success.
... Root and shoot length are widely used as growth indicators because they are important agronomic features that can easily be influenced by environmental stresses (Li et al. 2010). For instance, root growth is characterized by high metabolism and is therefore very sensitive to environmental changes, such as increases in soil allelochemicals (Chon et al. 2002). Similarly, toxic chemicals may alter plant water potential, which can hinder mineral and ion uptake thereby reducing fresh biomass (Weir et al. 2004). ...
Allelochemicals released by exotic plants can affect neighboring plants. In this study, we examined the effects of leachate extracted from shoots of an invasive clonal plant (Wedelia trilobata) on its own growth and performance, and that of its native congener (W. chinensis). Leachate from W. trilobata was prepared at concentrations of 0, 50, 75, and 100% and was applied to both Wedelia species (which were grown in mono and mixed culture). We monitored the effects of the leachate on plant growth, physiological traits, and relative competition intensity (RCI) in each species. Leachate concentration significantly affected the majority of growth and physiological traits in both species. Higher leachate concentrations significantly increased most traits of W. trilobata under mono and mixed culture. In contrast, many growth and physiological parameters in W. chinensis were significantly reduced in response to higher concentrations of leachate. Growth and physiological traits were higher in W. trilobata than W. chinensis at higher leachate concentrations in both mono and mixed culture. In W. trilobata, RCI significantly increased with increasing leachate concentration. However, RCI in W. chinensis remained consistently low in response to higher leachate concentrations. Overall, the addition of leachate from invasive W. trilobata had a strong allelopathic effect on native W. chinensis under mono and mixed culture. Conversely, growth and competitive ability in W. trilobata was enhanced in response to the leachate. Thus, allelochemicals from W. trilo-bata promote its own performance while simultaneously suppressing that of a native congener, which has likely contributed to its invasion success.
... Root and shoot length are widely used as growth indicators because they are important agronomic features that can easily be influenced by environmental stresses (Li et al. 2010). For instance, root growth is characterized by high metabolism and is therefore very sensitive to environmental changes, such as increases in soil allelochemicals (Chon et al. 2002). Similarly, toxic chemicals may alter plant water potential, which can hinder mineral and ion uptake thereby reducing fresh biomass (Weir et al. 2004). ...
Allelochemicals released by exotic plants can affect neighboring plants. In this study, we examined the effects of leachate extracted from shoots of an invasive clonal plant (Wedelia trilobata) on its own growth and performance, and that of its native congener (W. chinensis). Leachate from W. trilobata was prepared at concentrations of 0, 50, 75, and 100% and was applied to both Wedelia species (which were grown in mono and mixed culture). We monitored the effects of the leachate on plant growth, physiological traits, and relative competition intensity (RCI) in each species. Leachate concentration significantly affected the majority of growth and physiological traits in both species. Higher leachate concentrations significantly increased most traits of W. trilobata under mono and mixed culture. In contrast, many growth and physiological parameters in W. chinensis were significantly reduced in response to higher concentrations of leachate. Growth and physiological traits were higher in W. trilobata than W. chinensis at higher leachate concentrations in both mono and mixed culture. In W. trilobata, RCI significantly increased with increasing leachate concentration. However, RCI in W. chinensis remained consistently low in response to higher leachate concentrations. Overall, the addition of leachate from invasive W. trilobata had a strong allelopathic effect on native W. chinensis under mono and mixed culture. Conversely, growth and competitive ability in W. trilobata was enhanced in response to the leachate. Thus, allelochemicals from W. trilobata promote its own performance while simultaneously suppressing that of a native congener, which has likely contributed to its invasion success.
... It was reported that the alfalfa leaf extracts significantly reduced root lengths of alfalfa and barnyard grass. The root systems, especially root tips of alfalfa, were stunted and swollen by the aqueous alfalfa leaf extracts at 30 g L −1 and coumarin at 10 M (Chon et al. 2002). In this study, the root growth of A. thaliana could be promoted by oridonin at low concentration and be suppressed with the increasing concentration of oridonin in plc1 (Fig. 1a, d). ...
Oridonin is a diterpenoid isolated from medicinal herb Rabdosia rubescens (Hemsl.) Hara (Lamiaceae), which has an allelopathic effect on plants. Phospholipase C (PLC1) and hydrogen peroxide (H2O2) are involved in many biotic or abiotic stress responses. Using the 16-day-old seedlings of Arabidopsis thaliana ecotype (WT) and PLC1-deficient mutant (plc1) as materials (treated with 10 μM or 60 μM oridonin for 72 h), the effect of oridonin on root growth regulating by PLC1 and H2O2 was investigated. The results showed that the promoting of root growth was about 6.9% at 10 μmol L⁻¹ oridonin and the inhibiting of root growth was about 19.73% at 60 μmol L⁻¹ oridonin in WT, the inhibiting of root growth was about 10.5% and 41.2% at 10 mol L⁻¹ and 60 mol L⁻¹ oridonin, respectively, in plc1. The expression of ARR1, ARR12, and AHK3 was promoted at low concentrations of oridonin and inhibited at high concentrations in WT, whereas the expression of ARR1 and ARR12 was inhibited with the increase of oridonin concentration in plc1. This suggested that PLC1 was involved in the root growth regulation of oridonin. H2O2 was promoted by oridonin with concentration dependence pattern in root cells. Oridonin increased the activity of antioxidant enzymes in both WT and plc1, but the activity of antioxidant enzymes in plc1 was lower than WT. This indicated that PLC1 involved in the activation of antioxidant enzymes promoted by the oridonin. Exogenous CaCl2 facilitated the accumulation of H2O2 in both WT and plc1. And the H2O2 of WT was obviously higher than that of plc1. The root growth of WT was inhibited by CaCl2 with the increase of oridonin. However, there is no effect of CaCl2 on the root growth in plc1. This reflected that PLC1 positively involved in the regulation of Ca²⁺ on the H2O2 and the inhibition effect of Ca²⁺ on the root growth under oridonin treatment. PA promoted the H2O2 and suppressed the root growth under oridonin treatment in both WT and plc1. In plc1, PA facilitated the root growth with no oridonin and inhibited the root growth with the increase of oridonin. This reflected that PLC1 positively regulated the promotion effect of PA on the root growth under high oridonin treatment. PLC1 mediated oridonin (10 and 60 mol L⁻¹) to regulate H2O2 levels in A. thaliana seedlings, thereby regulating root tip cell morphology and mitosis. These results demonstrated that PLC1 mediated the low-promotion and high-inhibition effect of oridonin on the root growth in A. thaliana by regulating the concentrations of Ca²⁺ and PA, and further affecting the intracellular H2O2 level.
... Root-hair was not observed in those defective radicles. The similar pattern of growth inhibition by allelopathic chemical were reported in previous study (Chon et al., 2002). In their study, severe inhibition of root elongation in early seedling of alfalfa was accompanied by change of the root morphology. ...
Strategic utilization of organic material for agriculture is important for improve efficiency in organic agriculture. Waste from food processing is a good candidate for compost material, and the first critical step is to choose proper raw material. In this study, we tried to establish a reliable screening method by comparing growth of different plant parts in different crops in combination with serial dilution of raw material extracts. The raw materials compared here are tangerine pomace, herbal medicinal plant waste, bread, spent coffee ground (SCG). We also compared effect of organic fertilizer made of SCG, natural pesticides made of pyrethrum extract and neem oil. The results obtained from different kind of crops and plant parts give insight into growth enhancing or inhibitory effect of tested material which will be useful screening raw material to make organic fertilizer and crop protective materials. Int. J. Appl. Sci. Biotechnol. Vol 8(4): 417-421
... Besides, as the concentration increased, the radicle length of H. verticillata seemed stunted and turned brown. According to a study conducted by Sang-Uk, et al. [23], root systems especially root tips of alfalfa (Medicago sativa L.) were stunted and swollen after treated with the aqueous alfalfa leaf extracts at 30 g/L and coumarin at 10−3 M. Chuah et al. [24] reported that Chrysopogon serrrulatus extract was strongly suppressed the radicle growth of Asystasia intrusa by >85% at low concentration of 0.5%. The previous study conducted by Norhafizah et al. [15] found that the radicle length of H. verticillata was inhibited by 50% at a concentration ranging from 3 to 14g/L aqueous root extract of Pennisetum purpureum. ...
The massive used of synthetic chemical herbicides in crop production to meet the increasing demand had cause negativel impacts on the environment and ecosystem. Allelopathy approach of potential crops is a suitable alternative that should be explored to have sustainable weed management. The present study was conducted to determine the phytotoxic effect of aqueous curry leaves (Murraya koenigii (L.) Spreng.) extract on the emergence and seedling growth of the bioassay species, woody borreria (Hedyotis verticillata Lam.) under laboratory and nursery condition. The seed and seedling of bioassay species were treated with different concentration of aqueous curry leaves extract at 0, 20, 40, 60, 80 and 100g/L (laboratory) and 0, 50, 100, 150, 200 and 250g/L (nursery). The results showed that the aqueous curry leaves extract possesses a significant inhibition on seed emergence, shoot fresh weight and radicle length of H. verticillata at 100g/L concentration, where it reduced by almost 100% when applied as pre-emergence under laboratory condition. Meanwhile, the curry leaves extract at highest concentration of 250g/L significantly reduced the weed shoot fresh weight by 31% as compared to control and 50g/L concentration when treated at soil surface as post-emergence under nursery condition. Conversely, there is insignificant reduction in shoot height and root length of H. verticillata across all the applicate rates. These results suggest that curry leaves can be a good source to develop pre-emergence natural herbicide for weed management which is also eco-friendly for the environment and human beings.
... Vascular tissue and metaxylem area showed a complex behavior as it increased in few cases, but decreased in others when the allelochemical extract of A. scholaris was applied. Increased vascular bundle along with broader metaxylem vessels positively correlated with water movement through roots (Chon et al., 2002). Wheat lines that showed increased vascular tissue can survive better under stressful conditions (Donaldson, 2001) Pith parenchyma along with cortical parenchyma are water storing tissues in roots (Pereira at al., 2017). ...
... Most interestingly, Kim and Rhee (2012) showed using an in vitro enzyme activity assay with recombinant AtGA3ox1 protein that HCA and the Bacillus subtilis IJ-31 culture extract both inhibit GA3ox enzyme activity. The effects of these putative allelochemicals on seed germination has not been studied, but HCA has been shown to inhibit seedling growth in other species (Tang and Young, 1982;Williamson et al., 1992;Chon et al., 2002). Myrigalone A (MyA), 3-(1-oxo-3-phenylpropyl)-1,1,5-trimethylcyclohexane-2,4,6-trione (Figure 9.4e), a phytotoxin produced by Myrica gale L. ('sweet gale', 'bog myrtle', Myricaceae) has been demonstrated to inhibit seed germination and seedling growth of 'target' species (Popovici et al., 2011;Oracz et al., 2012;Voegele et al., 2012). ...
Gibberellins (GA) promote seed germination, but they are not simple 'Go Ahead' (GA) molecules as the insight gained into the molecular mechanisms underlying their role in seeds appears to be complex. This chapter covers their central role in mediating the environmental and developmental control of seed germination, and how this differs from vegetative growth processes. Spatiotemporal patterns of GA metabolism and GID1‐type receptor signalling in the key seed compartments determine tissue interactions and germination timing in response to ambient environmental cues. Gibberellins are key players in seed temperature responses; during thermoinhibition they interact with other hormonal pathways. Allelochemicals such as myrigalone A inhibit seed germination by specific interference with GA metabolism and signalling. This reveals important ecophysiological roles for GAs in seeds and suggests that they are fundamental for studying species adaptation and interaction in natural and agricultural ecosystems upon climate change.
... The presence of chemical compounds like coumarin, flvonoids, resin, phenol, and alkaloid in different parts of apple of Sodom, regardless of their quantity, has been found to prevent cell division, reduce induction and alter the stability of phytohormones, defect absorption and delivery of water in plant tissues. It is also reported that the aqueous leaf extract of apple of Sodom has allelopathic properties including germination inhibition and yield reduction (Chon et al., 2002;Ghasemi, et al., 2012). ...
Certain plants suppress development of other plants by releasing many chemical substances into the environment. This study was carried out to investigate the phytotoxic effects of the leaves aqueous extract of apple of Sodom [Calotropis procera (Aiton) W.T.] on seed germination of Sorghum bicolor (L.) Moench (sorghum), Pennisetum glaucum (L.) R. Br. (millet), Zea mays L. (corn) and Triticum aestivum vulgare L. (wheat) using probit analysis. The experiments were conducted at the University of Gezira in Sudan, in the 2014/15 agricultural season. Ten concentrations (2.11 to 21.05 g/l) were prepared from the stock solution (50 g / l). Sterilized-distilled water was used as control. The experiment for each crop, was laid out in a completely randomized design and the treatments were replicated four times. The crop seeds were checked for germination and its inhibition three days after the onset of germination. Data were subjected to probit analysis procedure (P ≤ 0.5). The results revealed that apple of Sodom's leaves aqueous extract inhibited seed germination of the tested cereal crops and there was direct positive relationship between concentration (g/l) and inhibition (%). In addition, the result revealed that the LC 50 was 17.6, 17.0, 19.2 and 16.7 g/l for sorghum, millet, corn and wheat, respectively. It was concluded that that the leaves aqueous extract of apple of Sodom had toxic effect to the seeds of the tested cereal crops.
... Afterwards, samples were oven dried at 60 • C for five days, ground to pass a 1 mm screen and then stored in a refrigerator at 2-4 • C until used [18]. Ten grams of each sample was soaked in 100 mL deionized water at 25 • C for 24 h on a shaker. ...
The integration of cover crops into cotton (Gossypium hirsutum, L.) production remains challenging. One potential negative impact of cover crops on cotton is allelopathy. Proper selection of cover crop species and termination timing could potentially reduce the impacts of allelopathy on cotton seedlings. Two studies were conducted to determine cotton germination and growth sensitivity to cover crop leachate, which were measured using (I) five cover crops species, including: oats (Avena sativa L.), hairy vetch (Vicia Villosa), winter pea (Lathyrus hirsutus), winter wheat (Triticum aestivum), and annual rye (Lolium multiflorum), and (II) a blend of cover crops at four termination timings, including: at planting, three weeks prior to planting, six weeks prior to planting, and a split termination, where a 25 cm band in the top of the bed was terminated six weeks prior to planting, and the remaining cover crop was terminated at planting (referred to as strip 6-wk). Samples for Experiment I were collected on May 24th and for Experiment II on March 22nd (Strip/6-wk and 6-wk), April 30th (3-wk), and May 11th (at planting) in 2018. The effect of 0 (deionized water), 25, and 50 (v/v) cover crop leachate extract on cotton seed germination was evaluated in a series of controlled environmental studies. All cover crop species’ leachates negatively impacted cotton germination and seedling growth (p < 0.05). Germination inhibition rates declined numerically by species, with winter pea ≥ hairy vetch ≥ oats ≥ annual rye ≥ winter wheat at the 50 v/v concentrations. Winter pea germination inhibition on cotton equaled 47.0% and cotton radicle length was decreased by 62.8%. Termination at planting suppressed cotton germination more than the other termination timings, with the 50 v/v treatment resulting in a germination inhibition of 60.0%. Proper selection of cover crop species and termination timing prior to planting cotton will be critical in maximizing the benefits and minimizing the risks of a cover crop.
Keywords: cover crops; termination timings; allelopathy; cotton
https://www.mdpi.com/2073-4395/10/5/638
... It has in fact been demonstrated that the presence of MES, although having the advantage of more pH stability, could affect roots processes like root exudation [69]. It was also observed that, while the mean root length decreased in the presence of the three allelopathic compounds, the mean root surface and diameter increased, resulting in shorter but thicker roots (Table 4) as previously observed for coumarin on alfalfa [70] and for rye allelochemicals on cucumber seedlings [71]. These results suggest that gramine, hordenine and N-methyltyramine could affect the root development on susceptible plants like lettuce. ...
The two alkaloids gramine and hordenine have been known for playing a role in the allelopathic ability in barley (Hordeum vulgare L.). These allelochemicals can be both found in leaves and roots in some barley cultivars whereas in others one seems to exclude the other. In this study eighteen accessions of barley from the Middle-East area, one accession from Tibet and the modern spring cultivar Barke, already used as parental donor in a nested associated mapping (NAM) population, were screened for their gramine, hordenine and N-methyltyramine (the direct precursor of hordenine) content in leaves, roots and exudates. Moreover, the toxicity of the three allelochemicals on root growth inhibition on lettuce (Lactuca sativa L.) was evaluated. Results of this study showed the preferential production of gramine and hordenine in leaves and roots, respectively, in the nineteen barley accessions. On the other hand, in the modern barley cultivar Barke, the highest content of hordenine in roots and the general lack of gramine suggests a favored biosynthesis of the former. Gramine was not detected in the root exudates. In additions, different metabolomic profiles were observed in wild relatives compared to modern barley genotypes. The results also showed the phytotoxic effects of the three compounds on root growth of lettuce seedlings, with a reduction in root length and an increase of root surface area and diameter. In conclusion, this study highlighted the impact of the domestication effects on the production and distribution of the two allelopathic alkaloids gramine and hordenine in barley.
... The observed increase in width may be related to the decreased root length, as mentioned in earlier reports. 30,31 The distinct development stages observed in this study, which occurred in the same region in relation to the root tip, are also associated with the inhibition of longitudinal root growth. 16,17 The REA extract also led to an early differentiation of both phloem and xylem fibers. ...
Herbicides are a key element in agriculture but they do cause environmental problems and natural alternatives are being sought. In this context, invasive plants could provide an as yet unexplored source for the development of future herbicides. Urochloa humidicola has great invasive potential in Brazilian environments as it hampers the establishment of other plants. The phytotoxicity of U. humidicola root extracts has been evaluated and the major components have been identified. The phytotoxicity of the extract was assessed in the wheat coleoptile assay, on seeds of troublesome weeds and on Anadenanthera colubrina, a tree species used in ecological restoration programs. The ethyl acetate extract showed the highest activity and the most affected weeds were E. crus-galli, M. maximus and A. viridis, with the latter weed more affected by the extract than by the herbicide Logran®. Microscopic ultrastructural analysis of A. colubrina roots indicated possible signals of cell death. Seven compounds were identified in the ethyl acetate extract, of which one diterpene and four saponins are new. Six of these compounds were tested in the wheat coleoptile bioassay. The most active were diterpene 1 and saponins 2, 3 and 6. The phytotoxic activity of U. humidicola explains the issues observed in ecological restoration with A. colubrina in the presence of Urochloa species, and its effect on weeds reinforces its potential use in agriculture.
... The Collet et al. 2006). La diminution du nombre de racines latérales réduit la surface 2971 d'échange avec le sol ainsi que le volume de sol exploré (Fitter et al. 1991 (Horsley 1977;Pardales et al. 1992;Chon et al. 2002;Amoo et al. 2008;Hossain et al. 2016). Un adage populaire suggère qu'il faut connaitre ses amis, mais encore plus ses ennemis. ...
A better understanding of plant interactions would improve the management of natural and artificial forest regeneration. It is well established that Molinia (Molinia caerulea), a monopolist species of understory, has a particularly depressive effect on young sessile oak (Quercus petraea) establishment and growth. Large capacity of Molinia in water and soil nutrients uptake leads to strong competition by resources exploitation. However, it seems that other interactions are involved in the relationship between young oak and Molinia. Thus, the allelopathic properties of Molinia have been suggested, but no study has shown such an effect on oak. Inversely, young oak seems to facilitate Molinia growth. Oak-Molinia interaction thus has the singularity of being antagonistic: the Molinia inhibits oak growth while this one favors grass growth, but the mechanisms involved are not entirely known. The aim of this thesis was to analyze the functional and ecophysiological mechanisms involved in the interactions between young sessile oak and Molinia. The experiments carried out in the thesis show that (i) oak quickly transfers nitrogen to Molinia by the underground pathways (rhizodeposition of nitrogen compounds in the soil) favoring grass growth, (ii) Molinia presence in the same pot leads to a decrease in the lateral root rate and ectomycorhization rate of oak and (iii) Molinia rhizodeposes secondary metabolites different from those of oak and have an allelopathic potential. In line with current work, the thesis puts into perspective that the chemical compounds emitted by plants in the soil act as real direct or indirect signals (via the biological communities of the soil) and induce neighbors modifications in their metabolism and / or their growth.
... Autotoxicity has been observed in both natural and managed cultivation systems. Plant roots and their exudates, bark, tissues, and also volatiles can cause autotoxicity and a number of studied have been reported in alfalfa (Miller et al., 1988;Dornbos et al., 1990;Chung et al., 2000;Chon et al., 2002), asparagus (Hartung et al., 1990;Miller et al., 1991), apple (Börner, 1959), cucumber (Yu and Matsui, 1994), eggplant (Chen et al., 2011), lettuce (Asao et al., 2004a, b;Lee et al., 2006), broad bean and pea , taro (Asao et al., 2003), tomato , and strawberry (Kitazawa et al., 2005). ...
Strawberry plants are grown in hydroponics for higher quality and yield, as this system excludes soil-borne disease issues. Recycled hydroponics is practiced to make cultivation cost-effective, sustainable, and environmentally friendly. However, due to recycling of hydroponic nutrient solution, plant root exudates accumulate, leading to autotoxicity, a form of allelopathy that inhibits growth and development. In recent decades, commercial cultivation of strawberry under greenhouse and plant factory conditions following recycled hydroponics has been widely adopted globally. Subsequently, yield decline has also been reported due to development of autotoxicity from the accumulated root exudates. In recycled hydroponic systems, strawberry plant growth is inhibited by root exudates that contain mainly phenolic acids in the culture solution. In this regard, elimination of these accumulated root exudates or allelochemicals from the culture solution would restore inhibited plant growth and yield. A number of research studies have been conducted on autotoxicity in strawberry and possible mitigation methods. These studies suggested that addition of activated charcoal in the nutrient solution, supplementation of auxin on leaves, electro-degradation of root exudates in nutrient solution, and supplementation of amino acids and/or LEDs can effectively remove/degrade/mitigate autotoxicity in strawberry grown under recycling hydroponics. This review mainly discusses the autotoxicity phenomenon in strawberry under recycled hydroponics, the responsible allelochemicals and their mechanism of action, mitigation methods and future research endeavors in this field.
... The presence of chemical compounds like coumarin, flvonoids, resin, phenol, and alkaloid in different parts of apple of Sodom, regardless of their quantity, has been found to prevent cell division, reduce induction and alter the stability of phytohormones, defect absorption and delivery of water in plant tissues. It is also reported that the aqueous leaf extract of apple of Sodom has allelopathic properties including germination inhibition and yield reduction (Chon et al., 2002;Ghasemi, et al., 2012). ...
... Leaf and stem hydroalcoholic extracts were the treatments which had greater inhibitory potential on the black-jack growth (Figs. 1 and 2). The plants produce numerous chemically diverse compounds with wide variation in polarity and distribution in the plant, with it being recognized that polar extracts can provide high expression of bioactive compounds, especially those related to phenolic compounds (Chon 2002, Leu 2002. The most expressive extracts on B. pilosa in this work have intermediate polarity (hydroalcoholic extract), indicating that extraction of the secondary compounds present in cagaita can be related to the balance between the polarities. ...
Cagaita (Eugenia dysenterica) is a native plant of the Cerrado with great economic, social and environmental importance. The objective of this work was to determine the phytotoxic potential of extracts of leaf and bark from the stem of E. dysenterica on the initial growth of B. pilosa (black-jack). The experiment was performed under laboratory conditions, and the extracts used were: leaf aqueous extract, leaf ethanolic extract, leaf hydroalcoholic extract 70:30, leaf hydroalcoholic extract 50:50, bark from the stem aqueous extract, bark from the stem ethanol extract, bark from the stem hydroalcoholic extract 70:30 and bark from the stem hydroalcoholic extract 50:50. All E. dysenterica leaf and bark from the stem extracts exerted inhibitory effects on the radicle and hypocotyl growth of black-jack seedlings. Thus, E. dysenterica leaf and bark from the stem extracts present high phytotoxic potential and may be useful in studies attempting to find new molecules with bioherbicidal function for controlling spontaneous plants.
... Einhelig (1995) reported that the presence in isolation or combination of two or more of these allelochemicals identified is all allelopathic sources. Similarly Fischer et al. (1994) and Chon et al. (2002) reported that allelochemicals such as coumarin, flvonoids, resins, phenols and many alkaloids were shown to inhibit cell division, changes in phytohormones and their balance, water uptake and germination of seeds. ...
Phytochemical screening and allelopathic activity of aqueous leaf extract of Calotropis procera on radicle and plumule length of millet and sorghum were investigated. The result obtained showed that Calotropis procera contain tannins, flavonoids, glycosides, steroids, saponins and cardiac glycosides which are important allelopathic sources. While alkaloids and anthraquinones were absent. The extracts brought about considerable inhibition in growth parameters of the seeds examined. The result obtained showed that the degree of retardation in radicle and plumule length of millet and sorghum increased with increase in the concentration of the extracts, which showed that the inhibition was concentration dependent. Statistical analysis (p< 0.05) revealed that there were significant differences in radicle and plumule length in millet and sorghum when compared with the control experiment. The control experiment had higher radicle and plumule length. The 20% concentration had the highest inhibition of radicle and plumule length when compared with the control. Therefore the study revealed that allelochemicals released from Calotropis procera extract had inhibitory effect on radicle and plumule length of millet and sorghum and would have inhibitory effect when grown alongside with the test crop.
... Petri dishes were placed in a growth room at 20 ± 2 C and a photoperiod of 14:10 h (light:dark), and a light intensity of 4000 lux. Treatments were arranged in a completely randomized design (Chon et al. 2002;Vidotto et al. 2013). ...
The phytotoxic potential of Veronica peregrina L. was assessed by determining its influence on the germination and growth of the test plant Sinapis alba L. and identification of the allelochemicals present in its tissues. The impact of water extracts of V. peregrina (the gradient of concentrations: 0.5%, 1%, 2% and 4%) on S. alba seed germination and growth (radicle and hypocotyl elongation) was studied in bioassay conducted on Petri dishes with 3-ply layer of filter paper. UHPLC/UV/MS (Ultra-high performance liquid chromatography with diode array detection coupled to electrospray time-of-flight mass spectrometry) was used to separate and identify the allelochemicals present in V. peregrina tissues. The material for the study (whole plants of V. peregrina) was sampled from two fishponds located in Lower Silesia in May of 2018. The results showed that V. peregrina inhibited the germination of seeds. The effect on shoots and roots growth was positive or negative depending on the concentration of extract—low concentrations stimulated while the high ones inhibited growth of seedlings. Three compounds probably responsible for allelopathic activity (protocatechuic acid, luteolin-7-O-glucuronide, verproside) were identified. Presented phytotoxic potential of the species may account for its competitiveness, thus explaining its invasive behavior.
... Seed germination of L. formosana was inhibited to varying degrees by aqueous extracts of C. migao. The higher the concentration of the extracts, more robust was their inhibitory effect on seed germination of the recipient plants, which is consistent with previously reported trends [36][37][38]. When the concentration of all extracts increased to 50 mg mL −1 , the germination rate and potential decreased rapidly. ...
We examined allelopathic effects and underlying mechanisms of Cinnamomum migao on its associated species Liquidambar formosana. We assessed effects of aqueous extracts of C. migao pericarp, leaf, and rhizosphere soil at different concentrations on seed germination, seedling growth, and physiology of L. formosana. All extracts inhibited L. formosana seed germination, with obvious inhibition at high concentrations (50 mg mL−1). All extracts promoted the height and ground diameter of seedlings, with the highest promotion achieved with aqueous leaf extract at a concentration of 1 mg mL−1 and aqueous pericarp and rhizosphere soil extracts at a concentration of 5 mg mL−1. All extracts promoted soluble protein accumulation in L. formosana seedlings, with the highest accumulation achieved with aqueous pericarp extracts. Aqueous leaf extract promoted soluble starch accumulation. Aqueous pericarp extract at concentrations of >10 mg mL−1 significantly increased soluble sugar content. Aqueous leaf and rhizosphere soil extracts at concentrations of >5 mg mL−1 increased proline accumulation. All extracts at concentrations of >1 mg mL−1 significantly increased malondialdehyde content. Aqueous pericarp and rhizosphere soil extracts at concentrations of 10 and 0.5 mg mL−1, respectively, promoted superoxide dismutase activity. Activities of soil urease, polyphenol oxidase, and catalase were significantly increased when the concentration of aqueous pericarp and leaf extracts exceeded 5 mg mL−1, and the activity of soil acid phosphatase significantly increased when the concentration of all extracts were 5 mg mL−1. According to the synthetic allelopathic index, the low- and medium-concentration extracts all showed a promoting effect, whereas high concentrations exhibited obvious inhibitory effects; furthermore, the comprehensive effect value of leaf water extraction was higher than that of the pericarp and rhizosphere soil. Thus, allelopathy can affect the long-term co-existence of C. migao and L. formosana.
... In some previous studies, the basal diameter and biomass of Eucalyptus grandis were inhibited by the decomposing leaf litter of Cinnamomum septentrionale (15). Extracted allelochemicals altersd the root cap ultrastructure, deformed radial cell mitosis and damaged the secretory function, seriously retarding the root growth and mineral nutrients absorption (7,8). Furthermore, drastic reduction of P n in I. balsamina supported the decrease in biomass and basal diameter by soil incorporated leaf litter, because the carbohydrates assimilated by photosynthesis contribute to tissue growth. ...
We studied the performance of Impatiens balsamina in soil incorporated with the leaf litter of Cinnamomum japonicum. The application of 40 or 80 g litter in 8 kg soil, significantly inhibited the vegetative growth and photosynthetic rate of I. balsamina. These treatments also changed the normal blooming pattern of the receptor plant. Though the fruit and seed yield per plant of I. balsamina was not influenced by C. japonicum leaf litter, but the seed yield per fruit was increased at the highest dose. Incorporation of boiled leaf litter to soil did not affect the growth of I. balsamina, which indicated that the allelochemicals of C. japonicum were neutralized by boiling i.e. high emperature. Eight compounds (terpenoids, aldehyde and esters, which are Dihydrocoumarin, 1,8-Cineole, Cinnamaldehyde, trans-Caryophyllene, alpha-Terpineol, (+)-Spathulenol, Caryophyllene oxide and Borneol L.), were found in C. japonicum leaf litter. These may be potential allelochemical candidates. In conclusion, C. japonicum leaf litter during its decomposition was allelopathic to I. balsamina. The allelopathic effects inhibited the carbon-fixation ability, thereby reduced the vegetative growth and flower production of I. balsamina. © 2018, International Allelopathy Foundation. All rights reserved.
The present study was conducted to evaluate the allelopathic potential of Lamiaceous weed species Leucas nutans (Roth) Spreng. and to identify the potent allelochemicals. Aqueous leaf extract at different concentrations was used to evaluate the seed germination and seedling development in both the in-vitro and soil conditions of three economically important crops i.e., chickpea, flax, and Gobindobhog rice. All the concentrations significantly reduced the seed germination, delayed its rate, and also affected the seedling growth of all tested crops. Based on the allelopathic index, a strong inhibitory effect was observed in Gobindobhog rice than the chickpea and flax. The in-vitro bioassay proved that the seed germination as well as the root length hampered the most while pot experiments showed that the root and shoot biomass were strongly affected. A total of 19 (11 phenolic acids and 8 flavonoids) potent allelochemicals were identified and quantified from the leaves through high-performance liquid chromatography (HPLC). The identification of potent allelochemicals from allelopathic plants against crops will help to understand the disadvantages of farming practices that play an effective role to prevent unwanted outcomes to secure sustainable crop productivity. The L. nutans is the first-time reported as an allelopathic plant on the selected crops from India. This study also emphasized the newly identified potent allelochemicals from the L. nutans. The study highlighted the allelopathic weed and crop interactions for better management and sustainability.
Glyphosate‐resistant (GR) alfalfa ( Medicago sativa L.) has been widely adopted in the United States. Exceptional tolerance of GR alfalfa to glyphosate application has been reported as a strength of this technology; however, growers have recently reported potential crop injury under specific environmental conditions. The purpose of this study was to document and characterize the injury and determine best management practices for avoiding injury to GR alfalfa in the Intermountain West. The effects of glyphosate rate and application timing during various seasons were investigated at 24 sites over 5 years, measuring the impact on alfalfa crop height and biomass yield. Summer glyphosate applications did not injure alfalfa. However, spring applications reduced crop height at 76% of sites and biomass yield at 62% of sites. At responsive sites, low (869 g ae ha ⁻¹ ) and high (1739 g ae ha ⁻¹ ) glyphosate rates reduced yield by 0.53 and 1.06 Mg ha ⁻¹ , respectively. Alfalfa treated with high rates in the late spring, when 15–20 cm tall, had mean yield reductions of 16%–17% compared with untreated alfalfa. These results suggest that glyphosate applications made at tall crop heights or high rates on GR alfalfa are more likely to reduce crop height and yield in the Intermountain West compared with earlier applications at lower rates. We recommend that spring applications using low glyphosate rates occur before alfalfa is 10 cm tall to mitigate the risk of injury. If a high glyphosate rate is necessary, then an application should be made before alfalfa is greater than 5 cm tall.
تناول البحث الحالي دراسة تأثير المركبات الأليلوباثية للمتبقيات النباتية للمجموعين الخضري، والجذري لنبات الحمص في بعض الصفات التشريحية لأصناف الحنطة (بحوث-4 , Debeira , Terbol). وقد شملت دراسة الصفات التشريحية لأوراق أصناف الحنطة المختبرة، وتشريح المقاطع المستعرضة للسيقان، فأظهرت النتائج اختلافات واضحة في الصفات المدروسة (عدد خلايا البشرة وأبعادها, عدد الثغور وأبعادها, طول وعدد الشعيرات, التردد الثغري، والمعامل الثغري) بتأثير المتبقيات النباتية، والمستخلصات المائية المعاملة بها. إذ وجد زيادة في عدد الثغور، والمعامل الثغري، والتردد الثغري، وعدد الشعيرات، وعدد خلايا البشرة في أغلب المعاملات ، فيما يخص الصفات التشريحية للسيقان (قطر المقطع, قطر اللب, عدد الحزم، وأبعادها) لوحظ وجود اختلافات معنوية في الصفات المدروسة للمقطع العرضي.
Production of allelopathic substances is a factor determining the ecological success of invasive plants-Canadian goldenrod (S. canadensis L.) and giant goldenrod (S. gigantea Aiton). This research aimed at evaluating the autoallelopathic effect of aqueous extracts (AEs) prepared from various parts of Canadian goldenrod and giant goldenrod against vegetative growth, and biomass accumulation of both goldenrods. In the stage of 5-6 leaves, goldenrod plants, were foliar sprayed with AEs, at concentrations of 5 or 10%. The biochemical properties of AEs, i.e., total phenolic content, total antioxidant potential and selected plant hormones, were examined. Two and ten days after spraying (DAS), damages to aboveground parts of goldenrods (necrosis and wilting) were visually assessed. The fresh mass of above-and belowground parts of goldenrods were measured 21 DAS. AEs from various parts of Canadian goldenrod or giant goldenrod displayed autoallelopathic properties of inhibitory nature. The phytotoxic potential of AEs varied depending on their source. Canadian goldenrod was more susceptible to the AEs, manifested by more significant damages to aboveground parts and a greater decrease in above-and belowground biomass. The most effective against growth and development of Canadian goldenrod and giant goldenrod were AEs from rhizomes, which caused a reduction of fresh biomass of goldenrods up to 42%, compared to water-treated control.
Bidens pilosa L. is a troublesome weed that affects the survival and production of crops. Our previous study showed that Brucea javanica (L.) residue has potent herbicidal activity against B. pilosa, and Bruceine D is the main active ingredient in the B. javanica residue. This study showed that Bruceine D significantly inhibited the germination of B. pilosa seeds, especially root hair, and it likewise showed a dose-dependent effect. Transcriptome results showed that phenylpropanoid biosynthesis was inhibited by Bruceine D (10 μg/mL). The expression of PAL, C4H, and 4CL genes were dynamic, whereas genes encoding COMT and POD remained significantly downregulated during Bruceine D treatment. The activities of these enzymes exhibited similar results. At the same time, the contents of several phenylpropanoid biosynthesis metabolites, including flavonoids and lignin, decreased in response to Bruceine D. Our results highlight the use of Bruceine D as a good candidate to develop bioherbicide.
An experiment was conducted to separate allelopathice of osmotic pressure of rye
different wheat cultivars: Alvand, Sayson, Navid and Toos. In first experiment, aqueous
extracts of rye at five concentration of 0 (control), 25, 50, 75 and 100 percent were
obtained. Treatments of second experiment were included osmotic pressure equivalent
to rye extract (0, 0.48, 0.95, 1.36 and 1.61 bar). Osmotic pressures were obtained by
PEG6000. Results showed that by increasing concentration of rye extract cumulative
percentage germination of wheat cultivars reduced. Also, percent and rate of
germination, length, fresh and dry weight of radicle and plumule of wheat were reduced
significantly. Sayson compared with other cultivars showed higher sensitivity to extract
and didnt germinate in concentrations over 25 percent. Osmotic pressure of prepared
extracts had a different effect on each of traits and cultivars. Increasing osmotic pressure
had few effects on changes trend of cumulative percentage germination of wheat
cultivars. Also, in most cases germination percentage and plumule dry weight didnt
show significant change. But in most of cultivars, germination rate, length and fresh
weight of plumule and radicle had significant reduction. Unlike other traits, radicle dry
weight of wheat cultivars showed significant increase by increasing osmotic stress.
Generally, the results of this research showed that the highest inhibitory effect of extract
on germination traits was related to allelopathic properties and osmotic pressure has
very little role.
The reactivity of 2‐alkynylbenzoic acids toward the Lawesson’s reagent (LR) agent under microwave irradiation (300 W, 100 °C, CH2Cl2) was assessed. It was found that, depending on reaction conditions, either a dithionation‐ or a monothionation‐cycloisomerization process may take place with formation of important sulfurated heterocycles. In particular, using 1 equiv of the LR for 1 h, dithionation occurred, with formation of benzo[c]thiophene‐1(3H)‐thiones or 1H‐isothiochromene‐1‐thiones, while with 0.5 equiv of the LR for 10‐30 min reaction time, monothionated products were selectively obtained (benzo[c]thiophen‐1(3H)‐ones or 1H‐isothiochromen‐1‐ones). The regiochemical output of the process strongly depended on the substitution pattern of the starting 2‐alkynylbenzoic acid derivatives. These compounds were also assayed as potential herbicides, by assessing their phytotoxic activity on seedling growth and development of the model species Arabidopsis Thaliana. All compounds, at different extent, influenced the morpho‐physiological parameters monitored; in particular, the Fresh Weight (FW) was significantly affected, with ED50 values ranging from 4.81 μM to 63.7 μM.
The aqueous extract of alfalfa (Medicago sativa L.) shoots inhibits root elongation, shoot elongation, and/or germination of alfalfa itself-a phenomenon termed autotoxicity. The study of the mode of action of allelopathic and/or autotoxic compounds at the plant organ and cellular levels is limited by the depth of field, resolution, and magnification of a light microscope compared to a scanning electron microscope. Scanning electron microscopy techniques were used to study the morphology and anatomy of the roots inhibited by the water-extract of alfalfa shoots. Investigations on the morphology of shoot-aqueous-extract-inhibited, 5-d old ‘WL-316’ alfalfa roots revealed a 46% reduction in density and 54% reduction in length of root hairs compared to the control. Anatomical differences between the inhibited and uninhibited alfalfa roots were also observed. Shoot aqueous extract did not cause clogging of xylem vessels. The scanning electron microscope is a valuable tool in the study of the mode of action of allelopathic or autotoxic compounds at the plant organ as well as cellular levels.
Part of the thesis of the senior author submitted to the Univ. of Illinois in partial fulfillment of the requirements for the degree of doctor of philosophy in agronomy.
Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Growth chamber tests demonstrated that alfalfa (Medicago sativa L.) residue is toxic to cucumber (Cucumis sativus L.) seed germination and seedling growth. Ground alfalfa roots at 0.5% (w/w, dry weight) inhibited germination when added to the grow-ing medium. Alfalfa roots at 0.5% were also toxic to pregerminated cucumber seed. However, cucumber seedlings grew normally if this same medium was watered and incubated for >1 day before planting. Alfalfa particle size in media influenced cu-cumber performance, with the intermediate size (1 to 2 mm) being lethal to cucumbers. Allelopathy describes the inhibiting effect of one plant upon another. Reports of such occurrences are numerous (Rice, 1974). The allelopathic effect of alfalfa is of particular concern since it is widely used in crop ro-tation. Under laboratory conditions, alfalfa residue inhibited cotton seed germination (Megie et al., 1967). This inhibition may Received for publication 26 Jan. 1990. Funding was provided by Colorado Agricultural Experi-ment Station (Project 156) and Colorado State Univ. Development fund (Project 5195). The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regula-tions, this paper therefore must be hereby marked advertisement solely to indicate this fact. 1 Associate Professor.
Greenhouse and laboratory experiments were conducted at the Agricultural and Water Resources Research Center Station, Baghdad, in 1985 and 1986 to investigate the possible allelopathic potential of alfalfa (Medicago saliva L.) and its decomposed residues on bladygrass (Imperata cylin-drica L. Beauv.), a noxious weed in Iraq, and to isolate, characterize, and quantify possible allelopathic agents in alfalfa residues and root exudates. Results indicated that decomposed alfalfa roots and their associated soil produced a 51-56% reduction in bladygrass seed germination. Root and shoot length of bladygrass seedlings were reduced by an average of 88%. Decayed and undecayed mixtures of alfalfa roots and soil at 0.015∶1 (w/w) inhibited bladygrass seedlings reproduced from rhizomes by 30 and 42%. It was found that root exudates of alfalfa seedlings caused significant reduction in shoot and root dry weights of bladygrass seedlings when alfalfa and bladygrass were grown together in nutrient culture. Caffeic, chlorogenic, isochloro-genic,p-coumaric,p-OH-benzoic, and ferulic acids were detected in alfalfa root exudates and residues. The highest amount (126 fig phenolic acids/g soil) of these compounds was found in alfalfa root residues after six months of decomposition in soil.
Problems associated with continuously planting alfalfa (Medicago saliva L.) or seeding to thicken depleted alfalfa stands may be due to autotoxicity, an intraspecific form of allelopathy. A bioassay approach was utilized to characterize the specificity and chemical nature of phytotoxins in extracts of alfalfa soils as compared to fallow soil or soil where a cereal was the previous crop. In germination chamber experiments, water-soluble substances present in methanol extracts of soil cropped to alfalfa or barley (Hordeum vulgare L.) decreased seedling root length of alfalfa L-720, winter wheat (Triticum aestivum L. Nugaines) and radish (Raphanus sativa L. Crimson Giant). Five days after germination, seedling dry weights of alfalfa and radish in alfalfa soil extracts were lower compared to wheat or red clover (Trifolium pralense L. Kenland). Growth of red clover was not significantly reduced by soil extracts from cropped soil. Extracts of crop residue screened from soil cropped to alfalfa or barley significantly reduced seedling root length; extracts of alfalfa residue caused a greater inhibition of seedling dry weight than extracts of barely residue. A phytotoxic, unidentified substance present in extracts of crop residue screened from alfalfa soil, which inhibited seedling root length of alfalfa, was isolated by thin-layer chromatography (TLC). Residues from a soil cropped continuously to alfalfa for 10 years had the greatest phytotoxic activity.
A large variety of secondary metabolites that can inhibit germination and/or seedling growth are produced by plants in low quantities. The objective of this study was to develop a bioassay capable of reliably assessing reductions in germination percentage and seedling length of small-seeded plant species caused by exposure to minute quantities of these compounds. The germination and growth of alfalfa (Medicago saliva), annual ryegrass (Lolium multiflorum), and velvetleaf (Abutilon theophrasti) were evaluated against six known phytotoxins from five chemical classes; cinmethylin (a herbicidal cineole derivative) was selected as a comparison standard. Each phytotoxin, dissolved in a suitable organic solvent, was placed on water-agar in small tissue culture wells. After the solvent evaporated, imbibed seeds were placed on the agar; after three days, germination percentages and seedling lengths were measured. Compared to a commonly used filter paper procedure, this modified agar bioassay required smaller quantities of compound per seed for comparable bioassay results. This bioassay also readily permitted the measurement of seedling length, a more sensitive indicator of phytotoxicity than germination. Seedling length decreased sigmoidally as the toxin concentration increased logarithmically. Phytotoxicity was a function of both compound and plant species. Cinmethylin, a grass herbicide, reduced the length of annual ryegrass seedlings by 90-100%, whereas that of alfalfa and velvetleaf was inhibited slightly. The agar bioassay facilitated the rapid and reliable testing of slightly water-soluble compounds, requiring only minute quantities of each compound to give reproducible results.
Most assessments of allelopathy involve bioassays. Our objective was to improve the sensitivity of an alfalfa (Medicago sativa L.) seedling bioassay for evaluating genetic tolerance to autotoxic leaf extracts. In a petri dish assay on imbibed seed, light inhibited hypocotyl elongation of controls and increased root elongation. Root growth was sensitive to the autotoxin in both light and darkness. An agar medium gave better root growth of controls and lower standard errors than did filter paper when petri dishes were placed on edge to encourage downward root growth or were placed fiat where roots grew laterally. Hypocotyl growth was not very sensitive to the autotoxic chemical(s) on either agar or paper medium when the plate was flat, because the hypocotyl arched upward to escape contact with the extract. Hypocotyl growth was sensitive in a rolled paper towel treatment held vertically because the hypocotyl remained in continuous contact with the extract. On agar plates placed flat, 50% inhibition of root length occurred at an extract concentration that was about 8% of that needed for 50% inhibition of germination at 36 and 48 h. Root growth was stimulated up to 15% above controls at very low concentrations of leaf extract. Root length at 120 h was the best indicator of autotoxic effects of alfalfa leaf extracts. We evaluated 17 germplasms and three cultivars of alfalfa for root growth response to the autotoxic chemical and found a twofold range (P < 0.05) in tolerance.
Secondary plant metabolites and their degradation products are important in all agroecosystems including those with forage crops. Allelopathy affects cropping systems and interseeding of one species into established sods of another. Autotoxicity and heterotoxicity are types of allelopathy. Alfalfa (Medicago sativa L.) has been investigated as both an autotoxic and heterotoxic species. Reestablishment of alfalfa immediately after alfalfa has usually resulted in poor stands due to autotoxicity, and several other forage species also exhibit autotoxicity. Many forage species have shown heterotoxicity, both between forage species and weed species. Several investigators have identified various allelochemicals and/or families of allelochemicals as being responsible for allelopathic reactions. Identifying such chemicals would aid in developing resistant forage cultivars and in maintaining a productive and profitable crop. Crop rotation, cover-crop management, interplanting, double cropping, no-till planting, and nonrotational cropping systems are involved with allelopathic effects. Some alfalfa cultivars possess some resistance to these allelochemicals. Therefore, a breeding program could provide resistant germplasms. Various forage grasses and some weed species have demonstrated allelopathic effects on alfalfa, and alfalfa has allelopathic effects on some weed species. This alone may provide an insight fur herbicide studies in alfalfa production.
There is a need to determine if alfalfa (Medicago sativa L. subsp. sativa) can be selected for low concentrations of allelopathic compounds. The objective of this study was to evaluate alfalfa cultivar differences in autotoxic traits in relation to various concentrations of aqueous extracts. Plant extracts from seven alfalfa cultivars (Apollo-Supreme, Arrow, Vernal, DK-125, Dawn, Pioneer 5472, and Magnum III) were evaluated in the laboratory for autotoxic effects on the same cultivar at four levels of extract solution (10,20,30, and 40% w/v). Double-distilled water was used as a control. Germination percentage, seedling length, and seedling dry weight were measured to determine the effect of the same cultivar extracts on alfalfa growth. These parameters were significantly reduced as the extract concentration increased. The highest concentration (40%) caused the greatest reduction in hypocotyl and radicle length, seedling dry weight, germination percentage, and seedling vigor in all cultivars. It also significantly increased the time required for germination. Autotoxicity effects were significantly different among the various cultivars. Cultivars may be classified in the following order of decreasing inhibition: Pioneer 5472, Arrow, Magnum III, Vernal, Apollo-Supreme, DK-125 and Dawn. The results indicate that there may be genetic differences among cultivars for resistance to alfalfa autotoxicity, and that selection for low autotoxicity may be possible.
Urbana-Champaign, IL 61801
Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Alfalfa (Medicago saliva L.) contains water-soluble substances that are toxic to itself (autotoxicity) and to other species (allelopathy). Experiments were conducted to determine the potential of using alfalfa residue as a natural herbicide for inhibition of weed seed germination, seedling growth, and development. Various weed species were germinated in aqueous extracts from dried alfalfa using cold (5°C), warm (24°C), and hot (80°C) treatments. Results indicated that inhibition of weed seed germination was dependent on the aqueous extraction method, residue application rate (w/v or w/w), and weed species. The greatest inhibition of germination was 44%, when 60% (w/v) warm aqueous extract was applied to lambsquarters (Chenopodium album L.). Seedling growth was also inhibited by residue application at various rates. Root length was more inhibited than increase in shoot length. In terms of total seedling length, giant foxtail (Setaria faberii Herrm.) was the most resistant species and lambsquarters was the most susceptible among the weed species studied to alfalfa aqueous extracts. Weed seed germination percentage decreased as incubation time increased from 8, 16, 24, and 48 h. An alfalfa aqueous extract incubated for 48 h caused the greatest inhibition of velvetleaf (Abutilon theophrasti Medic.) seed germination (25%). When alfalfa residue was incorporated with silica sand, the growth and development of lambsquarters, pigweed (Amaranthus retroflexus L.), velvetleaf, and crabgrass [Digitaria sanguinalis (L.) Scop.], as measured by plant height, leaf area, and total, shoot, leaf, and root dry weight, were significantly inhibited as the rate increased from 0.0 to 2.0 g kg⁻. Dried alfalfa residue significantly stimulated plant height, leaf area, and total dry weight including shoot, leaf, and root of giant foxtail and cheatgrass (Bromus secalinus L.). Results suggest that alfalfa residue has a contrasting effect on weed growth and development due to water-soluble allelochemicals present in the residue
Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Shoots of alfalfa ( Medicago sativa L.) contain water‐soluble chemical compounds which are autotoxic, i.e., inhibit the growth of alfalfa itself. The objectives of this study were to (i) determine the inhibition threshold of the water‐soluble chemical compounds (autotoxic principle), and (ii) demonstrate that the inhibition of seed germination on early seedling growth of alfalfa is due to autotoxinic compounds from alfalfa shoots and not from microbes. A farmer must make a decision on whether or not it would be advisable to replant alfalfa based on the level of alfalfa residue still growing in the field. Laboratory and greenhouse studies were conducted to determine if autotoxicity in alfalfa due to water‐soluble compounds is concentration dependent. Filter‐sterilized and non‐filter‐sterilized shoot aqueous extracts from vegetative and reproductive stages of ‘WL‐316’ alfalfa were assayed at 20, 40, 60, and 80 g L ⁻¹ (fresh shoot weight basis) for their effect on seed germination and root and shoot elongation of seedlings of WL‐316 alfalfa in a growth chamber. Compared with the control, root length, shoot length, and germination were inhibited beyond 20 g L ⁻¹ concentration. Shoot extract from the reproductive stage was more inhibitory than from the vegetative stage under laboratory conditions. In the greenhouse, incorporation of 4‐wk‐old green herbage from vegetative stage beyond 48 shoots per square meter level resulted in severe reductions in seedling emergence and plant fresh weight per unit area. Among the several phenolic compounds assayed for their phytotoxicity on root and shoot growth of alfalfa, coumarin and transcinnamic acid at 60 ± 10 μg mL ⁻¹ were the most inhibitory. Mixtures of five or more phenolic acids were more phytotoxic than their respective individual components except in the case of trans ‐cinnamic acid and coumarin. Autotoxicity in alfalfa may be caused by an interaction of many, yet uncharacterized chemical compounds present in shoots.
Sampling procedures of the donor material, conditions of the assay, and selection of test organism influence the sensitivity of a bioassay. Autotoxicity affects success of alfalfa (Medicago sative L.) reseeded after old alfalfa. Root length is a more sensitive parameter to autotoxin than germination or hypocotyl length. Our specific objective was to improve the sensitivity of an alfalfa seedling bioassay for a better understanding of the autotoxicity mechanism. Using a petri-dish assay with imbibed seed, we found extract of alfalfa leaves was more autotoxic than either that of stems or seed. Extracts from oven-dried samples were stronger than those from freeze-dried samples. Sterilization through membrane filtering or autoclaving did not alter autotoxicity bioassay. Root length at 25 or 50 seed/plate was more sensitive to the extracts than that at 100 or 200 seed/plate. Roots from older seedlings were more tolerant to the extracts than did those from seed or younger seedling and had more branch roots to escape the autotoxin(s). These results suggest that extracts from leaf samples that oven-dried and sterilized by filtering or autoclaving can improve the consistency and precision of bioassay. The bioassay was suitable with 25 to 50 seed per petri dish to minimize interaction on interference (e.g., competition and autotoxicity from testing seed itself). The bioassay can be improved by using very young roots from imbibed seed which are more sensitive to the autotoxin.
(…) Laboratory studies indicate that the autotoxic compound was contained within the water-extractable alfalfa fraction, and was not the direct result of microbial activity, although microbial activity may increase the dissipation of the compound. Ascending paper chromatographic separation indicated that the autotoxic compound had an Rf characterization similar to phenolic acid; however, phenolic-absorbent polyvinylpolypryrrolidone did not affect the autotoxic response. The results indicate that alfalfa contains a water-soluble autotoxic compound that has characteristics indicative of a phenolic compound
Genetic selection against the suspected toxic (“alfalfasick”) soil condition was ineffective. Replicated field comparisons of ‘Sel. Vernal’ and unselected certified ‘Vernal’ on two alfalfa-sick soils showed no significant difference in forage yield. Yields of four additional varieties also were uniformly depressed by the alfalfasick soils. Fertilizer treatments improved yields somewhat but did not correct the suspected toxic soil condition. Previous cropping to alfalfa appears responsible for the severely depressed growth of alfalfa.
Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Alfalfa (Medicago sativa L.) is known to be both autotoxic and allelopathic. Greenhouse and laboratory experiments were conducted to determine if WL-316 alfalfa exhibits short-term autotoxicity and long-term autotoxicity and allelopathy. Long-term autotoxicity and allelopathy of alfalfa were verified at Urbana, IL, by comparing the germination and growth of alfalfa and sorghum [Sorghum bicolor (L.) Moench] on Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) previously cropped to alfalfa (alfalfa-soil) and sorghum (sorghum-soil). Short-term autotoxicity of alfalfa was investigated by studying the effect of incorporating its roots only and both roots and shoots on the germination and growth of alfalfa in alfalfa-soil and sorghum-soil. The data were further supported by a laboratory bioassay of seedling exudate and shoot leachate of alfalfa and sorghum. Plant height and fresh weight per plant of alfalfa and fresh weight per plant of sorghum were lower on alfalfa-soil than on sorghum-soil. Germination percentages of both alfalfa and sorghum and plant height of sorghum were unaffected by the preceding crop. The two soils differed in nutrient content, but fertility was high and should not have been limiting to the growth of either crop. As a result, allelopathic/autotoxic compounds in alfalfa-soil were implicated in the growth inhibition of the two crops. Soil incorporation of fresh alfalfa roots only or both roots and shoots reduced alfalfa emergence, plant height, and dry weight per plant. Primary effects of water-soluble inhibitory compounds from alfalfa shoot appeared to be on germination and radicle elongation, the latter being apparently more sensitive than the former. Alfalfa allelopathy seems to be more severe than autotoxicity. A flow diagram describes different kinds of allelopathy and autotoxicity and various situations that verify the existence of a particular kind of allelopathy or autotoxicity
Alfalfa (Medicago sativa L.) plants contain water-soluble substances that inhibit the germination and seedling growth of alfalfa. Determining where allelochemicals may be found in alfalfa in the greatest concentration would aid in trying to isolate the compound or compounds responsible for autotoxicity. This study investigated the allelopathic effects of various alfalfa plant parts, and the soil in which alfalfa had been grown, on alfalfa germination and seedling growth. Aqueous extracts of alfalfa leaf, stem, flower, seed, and root plant parts were made to determine their effects on germination and dry weights of hypocotyl, radicle and total length of 5-d-old alfalfa seedlings over a range of extract concentrations. Soil samples (Flanagan series: fine, montmorillonitic, mesic Aquic Argiudolls) from around alfalfa plants at the vegetative and reproductive stages were compared with sterilized and nonsterilized soil formerly seeded with alfalfa, hairy vetch (Vicia villosa Roth), and winter rye (Secale cereate L.). Increasing the aqueous extracts concentrations of separated alfalfa plant parts significantly inhibited alfalfa germination, seedling length and weight. Radicle length was more sensitive to extract source than seed germination or hypocotyl length. Based on 5-d-old alfalfa radicle length growth, and averaged across all extract concentrations, the degree of toxicity of different alfalfa plant parts and soil from around alfalfa can be classified in order of decreasing inhibition as follows: leaf, seed, complete plant mixture, soil, root, flower, and stem. Leaf extracts (12 g kg⁻¹) caused a 48% decrease in water up take by alfalfa seed. Soil in which alfalfa had previously grown was the most inhibitory to alfalfa growth after 25 d of growth compared with soil where winter rye or hairy vetch had previously grown. Inhibitory effects were greater for soil collected around alfalfa grown at the reproductive than the vegetative growth stage. These data indicate that alfalfa autotoxicity may mult from a release of one or more water-soluble compounds from alfalfa leaf tissue.
Exp. Stn. Project 1-6-55179.
Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa 'Vernal' were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue 1-1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high-performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans-cinnamic acid and o-coumaric acid at 10-3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.
The distribution of free and covalently-bound phenolic acids was studied in various fractions obtained from fresh lucerne shoots. p-Hydroxybenzoic, vanillic, p-coumaric and ferulic acids were present, both free and bound, in all the fractions. Salicylic and sinapic acids occurred only in a bound, alkali-labile state and were found almost entirely in the ‘aqueous phase’ fraction after treatment of methanol-chloroform-water extract according to Bligh and Dyer. Many other common phenolics were absent. Amounts of the phenolic acids much larger than those extracted by methanol-chloroform-water were extracted subsequently by phenol-acetic acid-water and passed into the ‘diffusate’ fraction on dialysis of this extract against 70% acetic acid. Small, though significant, quantities of phenolic acids remained with the bulk protein in the ‘bag contents’ fraction. The extent to which the phenolic acids in these last two fractions are held to protein by covalent bonds or by secondary-valence attractions is discussed, particularly in relation to the isolation of N-feruloylglycylphenylalanine after partial hydrolysis. Suggestions are made for improving analytical procedures.
Typescript. Thesis (Ph. D.)--University of Missouri-Columbia, 1996. Vita. Includes bibliographical references (leaves 159-167).
Free and bound phenolic acids of alfalfa (Medicago sativa cv. Europe). Phytochem-istry 19
- V K Newby
- R M Sablon
- R L Synge
Newby, V.K., Sablon, R.M., Synge, R.L., 1980. Free and bound phenolic acids of alfalfa (Medicago sativa cv. Europe). Phytochem-istry 19, 651–657.
Autotoxicity of alfalfa. Max C. Fleischmann College of Agric
- E H Jensen
- B J Hartman
- F Lundin
- S Knapp
- B Brookerd
Jensen, E.H., Hartman, B.J., Lundin, F., Knapp, S., Brookerd, B., 1981. Autotoxicity of alfalfa. Max C. Fleischmann College of Agric., Univ. of Nevada Agric. Exp. Stn. Bull. R 144.
Allelopathy, 2nd Edition
- E L Rice
Rice, E.L., 1984. Allelopathy, 2nd Edition. Academic Press, New York, 422pp. S.-U. Chon et al. / Crop Protection 21 (2002) 1077–1082 1082
Allelopathy and autotoxicity in alfalfa
- Hedge