Mauricio Hunsche

• PD Dr.
• University of Bonn

The aim of this study was to investigate the effect of red light irradiation during postharvest ripening with focus on the outer (epicarp and mesocarp) and inner (endocarp and seed) parts of tomatoes by evaluating concomitant alterations in bioactive compounds, such as lycopene, β-carotene, total phenolic and total flavonoid concentrations, externa...

Rain wash-off of foliar-applied agrochemical formulations (i.e. active ingredients) is a key topic to ensure crop protection under rainy conditions and for some regions will gain higher importance due to global climate change. Rain-induced wash-off is determined by intensity and amount of rain, as well as by characteristics of the active ingredient...

Maximize process of pest control reducing loss in the agriculture process is fundamental. The aim this research was to achieve a different way to increase the herbicide activity, using potassium salts. Some experiments were conduct to analyze the efficiency of salts in enhanced the activity of two selected herbicides (paraquat and bromoxynil). Firs...

In tomato production, the accruing green biomass shows promising potential as source of health-promoting compounds, such as rutin and solanesol, that are of high interest due to their medicinal properties. Naturally, they accumulate in plants growing in suboptimal growing conditions, e.g. influenced by biotic and abiotic stressors. With the aim to...

The association of adjuvants with phytosanitary products has been tested for several years but is commonly recommended without considering technical and scientific criteria. This study aimed to evaluate the influence of the association of insecticides with different adjuvants on surface tension, contact angle, coverage, hydrogen ionic potential (pH...

The synthetic octapeptide NOP-1 inhibits ethylene downstream signalling by disrupting the ETR1- EIN2 interaction, resulting in ripening delay of tomatoes when applied at early ripening stages. In order to better understand the NOP-1 induced ripening delay, we investigated the effect of a repeated surface application of NOP-1 as well as its applicat...

In modern tomato production, plant residues deliver an enormous amount of biomass including high-value components that so far are mainly unused. Especially the flavonol glycosid rutin has received stronger attention in recent research as a potentially health-promoting substance and due to its natural occurrence in tomato plants. In this study, toma...

To reduce pesticide use while preserving crop productivity alternative pest and disease control measures are needed. We thought of an alternative way of functionalizing leaves of the soybean crop to fight its most severe disease, Asian soybean rust (Phakopsora pachyrhizi). To do so, we produced bifunctional peptides that adhere to the soybean leaf...

The impact of postharvest red light irradiation via LED modules on the content of health promoting compounds was evaluated on green tomatoes stage 1 exposed to intermittent or continuous irradiation. The first experiment studied the overall effects of different duration periods of red light radiation (darkness, continuous red light for 10 d, contin...

BACKGROUND Processes extending the shelf life of climacteric fruit play an important role in terms of a sustainable global food supply. In a previous study, a synthetic octapeptide (NOP‐1) was shown to inhibit the interaction between ethylene receptor (ETR) and ethylene insensitive‐2 (EIN2), and in consequence delay tomato ripening. We investigated...

Worldwide, increased drought stress induced by water shortages will be especially hazardous for maintaining high yields in agricultural and horticultural crops. It is known that not only do different crops have different water requirements, but that these can also vary between cultivars. Most commonly, plant responses to drought stress are monitore...

The application of artificial light to improve crop production in greenhouses is widely used in the horticultural sector. In this study, we evaluated the impact of light quality on sweet pepper plants’ physiology during a period of water deficit. Pepper plants were cultivated in a climate chamber and exposed to three different light regimes; (compa...

Adjuvants such as surfactants are commonly incorporated into agrochemical formulations to enhance the biological efficiency of foliar sprays by improving the wetting behavior of the spray and/or the penetration of the active ingredients into the leaf tissues. Penetration accelerating adjuvants are known to increase the cuticular permeability and ma...

Some 40 years ago, air pollution caused widespread forest decline in Central Europe and eastern North America. More recently, high levels of tree mortality worldwide are thought to be driven by rising temperatures and increasing atmospheric drought. A neglected factor, possibly contributing to both phenomena, is the foliar accumulation of hygroscop...

Agricultural residues are natural sources for secondary metabolites as high value ingredients for industrial uses. The present work aims to exploit the accumulation potential of rutin and solanesol in tomato leaves following nitrogen and general mineral deficiency in a commercial-like greenhouse. Physiological responses of tomato plants were monito...

Background We examined the suitability of chlorophyll fluorescence‐based indices to monitor and predict concentrations of fruit maturity compounds during tomato ripening under different growing conditions in the greenhouse. The aim of this study was to evaluate the effects of chlorophyll concentration changes on fluorescence‐based indices and to ex...

The precise understanding of the interactions of adjuvants, agrochemicals and foliar fertilizers is essential to improve the efficacy of spray applications. In this study, we explored the influence of manganese foliar fertilizers (manganese sulfate and manganese nitrate) tank-mixed with an insecticide (chlorantraniliprole) and one organosilicone su...

Due to their health benefits, high concentrations of antioxidative compounds in vegetables and fruit are important for end-consumers. The aim of this research was to investigate the effects of continuous red light and short periods of daily ultraviolet (UV) radiation on the postharvest quality of green tomatoes. Green tomatoes were exposed for 30 m...

Ethylene signaling is decisive for many plant developmental processes. Among these, control of senescence, abscission and fruit ripening are of fundamental relevance for global agriculture. Consequently, detailed knowledge of the signaling network along with the molecular processes of signal perception and transfer are expected to have high impact...

Previous flux measurements in the perhumid cloud forest of northeastern Taiwan have shown efficient photosynthesis of the endemic tree species Chamaecyparis obtusa var. formosana even under foggy conditions in which leaf surface moisture would be expected. We hypothesized this to be the result of 'xeromorphic' traits of the Chamaecyparis leaves (hy...

In a greenhouse study, we aimed to determine whether a temporary water deficit induces ‘drought memory’ in sugar beet (Beta vulgaris L.), and whether this effect can be quantified by alterations in the fluorescence signature of the leaves. Plants were subjected to three consecutive water deficit phases, each followed by a recovery period, and in ea...

The aim of the present study was to evaluate the morphological and physiological response of pepper plants (Capsicum annuum L.) as affected by different light regimes. In this context, we hypothesized that the illumination with proportionally high blue light under low light conditions induces stress-related responses and leads to stronger accumulat...

Foliar fertilization, or the application of nutrient solutions to the foliage of plants, has become a very important tool as a supplement to traditional soil fertilization. So far, knowledge about the real mechanisms of foliar nutrient uptake is still limited. In this study different manganese (Mn) and zinc (Zn) carriers differing in their solubili...

Wild edible fruits hold great potential for improving human diets, especially in agricultural societies of the developing world. In Africa, a well-known supplier of such fruits is the baobab (Adansonia digitata L., Malvaceae), one of the most remarkable trees of the world. Several studies in different African countries have highlighted this indigen...

Off-target deposits of agrochemicals impose a general risk for the environment while environmental factors such as rainfall might cause significant pesticide removal from agricultural crops and contribute to a requirement for a higher rate and frequency of applications in intensive agricultural systems. In the present study, we analyzed the impact...

The aim of our work was to examine the suitability of chemically induced osmotic stress by polyethylene glycol (PEG) for drought stress experiments based on key physiological parameters of apple (Malus domestica Borkh.) leaves. In this context, we hypothesized that PEG-induced osmotic stress influences the plant physiology in a similar manner as ph...

We investigated the influence of light quality on the vulnerability of pepper plants to water deficit. For this purpose plants were cultivated either under compact fluorescence lamps (CFL) or light-emitting diodes (LED) providing similar photon fluence rates (95 µmol m(-2) s(-1)) but distinct light quality. CFL emit a wide-band spectrum with domina...

We examined the effects of ambient, non-stressing ultraviolet (UV)-B (280–315 nm) level combined with different intensities of photosynthetic active radiation (PAR, 400–700 nm) on the accumulation of the lignan (−)-hinokinin, in leaves and stems of Hydrocotyle leucocephala. Plants were exposed in sun simulators under almost natural irradiance and c...

In our study, we investigated whether multiple fluorescence indices may be used to sense physiological changes in tomato plants (Solanum lycopersicum L.) caused by salinity and water deficit as single or combined stresses. The fluorescence intensity in the blue (B), red (R) and far-red (FR) spectral regions and the pulse-amplitude-modulated (PAM) c...

Thermoluminescence emission from wheat leaves was recorded under various controlled drought stress conditions: (i) fast dehydration (few hours) of excised leaves in the dark (ii) slow dehydration (several days) obtained by withholding watering of plants under a day/night cycle (iii) overnight rehydration of the slowly dehydrated plants at a stage o...

The objective of this study was to better understand the role of chaotropic and kosmotropic salts in stomatal uptake, a process that occurs in parallel with cuticular penetration and affects the bioefficacy of glyphosate. In Trial 1, salt solutions of kosmotropic (NH4)2SO4 and chaotropic NaClO3, with or without the organosilicone surfactant, Break-...

In the last years fluorescence spectroscopy has come to be viewed as an essential approach in key research fields of applied plant sciences. However, the quantity and particularly the quality of information produced by different equipment might vary considerably. In this study we investigate the potential of three optical devices for the proximal s...

The aim of our study was to identify appropriate multiparametric fluorescence ratios to evaluate the response of tomato (Solanum lycopersicum) genotypes to salinity. In this context, we hypothesized that the fluorescence indices BFRR_UV, FLAV, NBI and SFR provided by the multiparametric fluorescence technique reveal the impact of salinity on tomato...

Using potted sugar beet plants we aimed to investigate the suitability of four fluorescence indices to detect and differentiate the impact of nitrogen supply, water deficit and powdery mildew in two sugar beet cultivars (Beta vulgaris L.). Plants were grown inside a polytunnel under two nitrogen levels combined with water deficit or full irrigation...

We explored the potential of fluorescence ratios, based on multiple fluorescence excitation indices, as compared to chlorophyll fluorescence (ChlF) recorded with the pulse amplitude modulation (PAM) technique, for early and sensitive detection of water deficiency (WD) in tomato (Solanum lycopersicum) leaves. In this context, we hypothesized that th...

We explored the potential of fluorescence ratios, based on multiple fluorescence excitation indices, as compared to chlorophyll fluorescence (ChlF) recorded with the pulse amplitude modulation (PAM) technique, for early and sensitive detection of water deficiency (WD) in tomato (Solanum lycopersicum) leaves. In this context, we hypothesized that th...

Leaf diseases, such as powdery mildew and leaf rust, frequently infect barley plants and severely affect the economic value of malting barley. Early detection of barley diseases would facilitate the timely application of fungicides. In a field experiment, we investigated the performance of fluorescence and reflectance indices on (1) detecting barle...

“Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about t...

Recently, we have shown the relevance of nitrogen (N), phosphorus (P) and potassium (K) supply levels for resource partitioning between primary and secondary metabolism, and the concentration of centellosides in Centella asiatica L. Urban leaves. So far, no efforts have been made to investigate the effects of mineral supply on flavonoid concentrati...

Greenhouse and field experiments were carried out to evaluate the potential of specific fluorescence emission parameters for the detection of a temporary water deficit in selected sugar beet (Beta vulgaris L.) genotypes. Changes in the plant physiology due to reduced water availability were recorded with a multiparameter fluorescence sensor in addi...

Aerosols are an ubiquitous component of the atmospheric environment of plants but their ecophysiological role is largely unknown. Here we address this role by comparing the water relations of plants grown in ventilated greenhouses with ambient air (AA), and filtered air (FA) where particle concentrations had been reduced by more than 99%. Beans and...

The sensor-based monitoring of diseases under controlled conditions establishes an objective tool that allows a better understanding of the pathogen-plant interactions in different situations. The purpose of our work was to implement the presymptomatic detection of powdery mildew on wheat leaves shortly after fungus inoculation by spectral and time...

The deposit pattern of foliar-applied agrochemicals, and its relation to their bio-efficacy, has major practical importance. Thus, in our experiments, we evaluated the relevance of the deposition properties of glyphosate for its bio-efficacy. The deposition pattern of glyphosate monodroplets was influenced by using surfactant and by applying the dr...

A simple and robust monodroplet generator was constructed for drop-on-demand application of aqueous solutions of pesticides to crop plants and weeds. A short current impulse regulated the opening of a solenoid valve, allowing pressurised nitrogen gas to flow into a liquid chamber. Once a jet is released from the nozzle, one single droplet is detach...

The recent visualization of stomatal nanoparticle uptake ended a 40‐yr‐old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension....

Hyperspectral reflectance data were collected at 7 critical phenological stages in a summer barley field with 7 varieties in 2010, without artificial nutrient gradients. Throughout the range of 350 to 1800 nm, all possible two-bands combinations for the simple ratio (SR = Rj/Ri) and the normalized difference vegetation index (NDVI = (Rj−Ri)/(Rj+Ri)...

In recent years, several studies have shown the impact of adjuvants on the characteristics of herbicide deposits on leaf surfaces. Until now, most studies have addressed the distribution of active ingredients (AIs), whereas few experiments have focused on the location of the adjuvants. The objective of this study was a systematic examination of the...

EFFECT OF PVC AND POLYETHYLENE FILMS ON THE CO 2 ACCUMULATION AND MAINTENANCE OF POSTHARVEST QUALITY OF 'TANGI' STRAWBERRIES. This work was carried out with the aim to evaluate the effect of thickness of PVC and polyethylene films on the CO2 accumulation and it effects on the maintenance of postharvest quality of 'Tangi' strawberries. The PVC film...

STORAGE OF 'OSO GRANDE' STRAWBERRIES (Fragaria ananassa L.) UNDER HIGH CO2 PARTIAL PRESSURE. The aim of this work was to evaluate the effect of high CO2 partial pressures on the increase of postharvest life of 'Oso Grande' strawberries. Two experiments with a completely randomized design, with four replicates of 18 fruits were carried out. The stra...

Early recognition of pathogen infection is of great relevance in precision plant protection. Pre-symptomatic disease detection is of particular interest. By use of a laserfluoroscope, UV-light induced fluorescence data were collected from healthy and with leaf rust inoculated wheat leaves of the susceptible cultivar Ritmo 2–4days after inoculation...

In this work, the effect of microclimate at the tree level inside a polytunnel and in an uncovered orchard of Prunus avium was studied through the observation of leaf and fruit micromorphology and the accumulation of cuticular waxes. Records of environmental parameters showed a significantly higher daytime temperature in the polytunnel (on an avera...

In the present study we show for the first time the suitability of the laser-induced fluorescence technique to evaluate in vivo herbicide-induced damages as revealed by changes of fluorescence spectra and lifetime. Four herbicides of different modes of action (glyphosate, bromoxynil, mesotrione, and amitrole) were selected and applied to four weed...

In the present study we aimed to investigate the relevance of either N, P or K supply for herb and leaf yield and for centelloside concentrations in Centella asiatica L. Urban leaves. In this regard, we elucidated the causal relationship between assimilation rate, leaf N, P and K concentrations, herb and leaf production, and centelloside accumulati...

The incidence of hailstorms is on the increase, possibly due to global climate change, resulting in the installation of hailnets in many fruit orchards throughout the world. The objective of this work was to examine the effects of coloured hailnets and their structure on light transmission, light spectra, microclimate, micromorphology and permeabil...

In modern agriculture, the use of cultivars that are resistant against specific stresses, e.g. pathogen infections, is an integral component. Considering the great demand for a rapid and objective screening method for stress resistance of new cultivars, the question arises, whether time resolved fluorescence spectroscopy is suitable for such purpos...

Application of copper fungicides is an integrative component in the control of apple scab. As shown in the past, tank-mix adjuvants might reduce the rain-induced removal of active ingredients. The aims of this study were a) to characterize the impact of defined rain amount on the removal of Cu-oxychloride (Cu-Ox) and Cu-hydroxide (Cu-Hyd) from appl...

The development and optimization of protocols for the precise and pre-symptomatic detection of diseases, and non-invasive evaluation of genotype-specific pathogen resistance enabling selection of the more promising genotypes in breeding programmes are important and often overlooked topics in precision agriculture. The increasing pressure to minimiz...

This study addresses the physiological response of four tomato genotypes with distinct sensitivity to high NaCl concentrations, with the aim of identifying physiological traits to rank the genotypes’ sensitivity to salt stress. The central hypothesis was that tomato genotypes grown in saline environments show a characteristic salinity-triggered abs...

A higher frequency of hail storms, possibly due to climate change, has led to increased installation of hail nets worldwide. The objective of the present work was to investigate potential effects of the microclimate under these hail nets on micromorphological characteristics of the leaves and adaxial leaf cuticles. Leaves of apple cultivars 'Pinova...

Seedlings of the salt-tolerant plant grewia [Grewia tenax (Forssk.) Fiori] and the moderately salt-tolerant tamarind (Tamarindus indica L.) were grown under controlled conditions and treated daily with NaCl solutions to investigate mechanisms of tolerance to salinity. Leaf micromorphology, cuticular wax load, chlorophyll fluorescence and light remi...

Theoretical explanations of dew formation usually consider a pure, plain surface and do not include any contributions of hygroscopic material present on this surface. A significant amount of hygroscopic material, however, is present on most real leaves, due to accumulated deposited aerosols, salt exudations, leached ions, or agricultural sprays. Si...

In modern agriculture there is a great demand for a rapid and objective screening method for stress resistance, because so far, the resistance of new cultivars is tested in time- and money consuming field experiments. Based on fluorescence ratios, and lifetime of fluorophores measured by fluorescence spectroscopy, we have postulated that an early d...

In the present study the principle of energy dispersive X-ray microanalysis (EDX), i.e. the detection of elements based on their characteristic X-rays, was used to localise and quantify organic and inorganic pesticides on enzymatically isolated fruit cuticles. Pesticides could be discriminated from the plant surface because of their distinctive ele...

The effect of two ethoxylated rapeseed oils (RSO) as surfactants for foliar-applied calcium chloride CaCl2 and calcium acetate Ca(CH3COO)2 on deposit characteristics, penetration, and calcium (Ca) residues after rainfall was investigated in columnar apple trees (CAT, Malus domestica Borkh.) and apple seedlings. Irrespective of salt and apple variet...

Typical active ingredient (AI) residue patterns are formed during droplet drying on plant surfaces owing to the interaction of spray solution characteristics and leaf micromorphology. Currently, comparatively little is known about the influence of AI deposit patterns within a spray droplet residue area on the penetration and biological efficacy of...

Nutrient input by atmospheric particles is important or even essential for forest ecosystems. Many particles will first deposit to leaf surfaces. Competition is avoided by direct foliar uptake, compared to uptake via the soil. While there is meanwhile clear evidence for foliar uptake to happen via the stomata under natural conditions, this requires...

Calcium penetration from salt solutions of calcium chloride and calcium acetate was measured through isolated tomato fruit (Solanum lycopersicum L., cultivar ‘Panovy’) cuticles after 4, 24, and 48h. Droplet spread area (volume=1μL) and the area ultimately covered with calcium were determined with a scanning electron microscope which has an integrat...

In our studies, we evaluated the relation between CaCl(2) concentration and the scanning electron microscope-energy dispersive x-ray microanalysis parameters, net intensity, peak/background and standardized percentage of atoms and percentage of weight after application of single microdroplets on enzymatically isolated tomato fruit cuticles and appl...

In modern agriculture, there is a demand for rapid and objective screening methods of pathogen resistance of new cultivars. Using the pulse amplitude modulated (PAM) fluorescence-imaging technique as a non-destructive method for such purposes we hypothesised, that not only disease detection but also discrimination of wheat (Triticum aestivum) culti...

This study evaluated the effect of rapeseed, linseed, and soybean oil ethoxylates on the rheological characteristics of the spray solution, the deposit formation and rain fastness of the contact fungicide mancozeb on leaves of "Golden Delicious' apple seedlings. The greatest influence on surface tension and contact angle was observed by adding the...

In order to investigate the impact of rapeseed oil ethoxylates (RSO) as tank-mix-adjuvants on the biological efficacy of glyphosate, three selected weed species (Abutilon theophrasti, Chenopodium album, and Setaria viridis) were exposed to three rain intensities (0.5 mm h-1; 5 mm h-1; 48 mm h-1) 2 h after herbicide application. Total precipitation...

In our studies apple seedlings (Malus domestica Borkh.) were used as model plants to elucidate the influence of drying time of the deposit, rain intensity, and rain volume on rainfastness of the contact fungicide mancozeb. Light (0.5 mm h−1), heavy (5 mm h−1), and torrential (48 mm h−1) rain events were simulated using a laboratory rain simulator....

It is not clear so far whether alteration of leaf micromorphology and surface wax chemistry due to the impact of environmental factors, such as UV-B radiation, affects retention and rainfastness of applied pesticide solutions. In this study; UV-B treated and untreated adaxial leaf surfaces of apple seedlings (Malus domestica Borkh.) were characteri...

The influence of four linseed oil ethoxylate adjuvants (LSO 10, LSO 0903, LSO 30, LSO 3003) on the rain-induced wash-off and biological efficacy of glyphosate was studied using lambsquarter (Chenopodium album L.), velvetleaf (Abutilon theophrasti Medik.), and green foxtail (Setaria viridis L.). In addition, the adaxial leaf surface of weed species...

A study was made of the influence of the upper leaf surface characteristics on the retention and rainfastness of the contact fungicide mancozeb with and without tank-mix adjuvants (RSO 5 and RSO 60) on apple seedlings, bean seedlings and kohlrabi plants. Large differences in roughness, in the amount and composition of surface waxes and in the reten...

The objective of this study was to evaluate the effects of soil K fertilization on fruit mineral composition, quality and storability of 'Fuji' apples. Fruits from a longterm trial that evaluated apple response to annual soil applications of K2O for nine years were harvested in the 1999/2000 growing season and stored in controlled atmosphere (CA) o...