Search

Protein hydrolysates (PHs) are a prominent category of plant biostimulants, mainly constituted of amino acids, oligopeptides and polypeptides, obtained by partial hydrolysis of animal or plant protein sources. Despite scientific evidence supporting the biostimulant action of PHs on vegetables, the morphological, physiological, and shelf-life performances underlying the PH action on cut flowers are still poorly explored. Accordingly, the aim of this research is to assess the effects of three commercial biostimulants, one animal PH (PH A, Hicure®) and two plant PHs (PH V1, Trainer® and PH V2, Vegamin©), on two chrysanthemum (Chrysanthemum morifolium) cultivars (Pinacolada and Radost). In both cultivars, only the plant-derived PH (V1 and V2) treatments recorded significantly higher fresh plant biomass than the control (on average +18%, in both cultivars). The foliar application of the vegetal-derived PHs but not the animal one, particularly in Pinacolada, improved the status of plants, stimulating stem elongation and the apical flower diameter. In Pinacolada, applications with PH V1 resulted in a significant increase in nitrate and P concentration in leaves and Ca content in flowers compared with the control (+43%, +27%, and +28% for nitrate, P, and Ca, respectively). In Radost, PH A and PH V2 applications caused a significant reduction in nitrate concentration in both leaves and flowers compared with the control. One week after harvest, in both cultivars, PH A applications caused flower stems to wilt faster than the control. In contrast, plants treated with PH V1 revealed significantly slower flower stem senescence compared to the control. Flower wilting during vase life was correlated to a decrease in the K-to-Na ratio in flowers due to an inability to transport K to the flowers from the leaves rather than an increase in Na in the flowers themselves. [ABSTRACT FROM AUTHOR]

Calcium deficiency or its inefficient translocation to pepper fruits leads to considerable economic loss by reducing the number of marketable fruits. The present study proposes grafting as an environmentally friendly technique to effectively reduce such loss. A commercial variety (Al-cudia F1; V) was grafted onto two pepper (Capsicum annum L.) accessions (V/A6 and V/A8), a hybrid rootstock (V/N) and was also self-grafted (V/V). All rootstock–scion combinations were cultivated under greenhouse conditions with optimal and suboptimal Ca supply and assessed for fruit yield and biomass production, gas exchange and chlorophyll fluorescence, mineral concentration in leaves and fruits as well as several fruit quality parameters. The V/N plants demonstrated an enhanced capacity for increased biomass, higher yield and number of commercial fruits and greater mean fruit weight compared with the other rootstock–scion combinations. These improvements are attributed primarily to increased intrinsic water efficiency. Additionally, a significantly higher Ca concentration in leaves was found under suboptimal Ca conditions in the V/N combination than that found in the other rootstock–scion combinations indicating a higher capacity for Ca uptake and translocation. Under the same conditions, the concentration of organic acids in fruits, such as citric and tartaric, which impact the organoleptic quality, was also higher in V/N plants. Consequently, we can conclude that grafting pepper onto tolerant rootstocks is a successful tool for ameliorating the negative impact of suboptimal Ca conditions on pepper crop performance and fruit quality. [ABSTRACT FROM AUTHOR]

In the coming years, farmers will have to deal with growing crops under suboptimal conditions dictated by global climate changes. The application of plant biostimulants such as beneficial microorganisms and plant-derived protein hydrolysates (PHs) may represent an interesting approach for increasing crop tolerance to alkalinity and salinity. The current research aimed at elucidating the agronomical, physiological, and biochemical effects as well as the changes in mineral composition of greenhouse lettuce (Lactuca sativa L.) either untreated or treated with a microbial-based biostimulant (Tablet) containing Rhizophagus intraradices and Trichoderma atroviride alone or in combination with a PH. Plants were sprayed with PH at weekly intervals with a solution containing 2.5 ml L-1 of PH. Lettuce plants were grown in sand culture and supplied with three nutrient solutions: standard, saline (25 mM NaCl) or alkaline (10 mM NaHCO3 + 0.5 g l-1 CaCO3; pH 8.1). Salt stress triggered a decrease in fresh yield, biomass production, SPAD index, chlorophyll fluorescence, leaf mineral composition and increased leaf proline concentration, without altering antioxidant enzyme activities. The decrease in marketable yield and biomass production under alkali stress was not significant. Irrespective of nutrient solution, the application of Tablet and especially Tablet + PH increased fresh marketable yield, shoot and root dry weight. This was associated with an improvement in SPAD index, Fv/Fm ratio, CAT and GPX activities and a better nutritional status (higher P, K, and Fe and lower Na with NaCl and higher P and Fe with NaHCO3) via an increase of total root length and surface. The combination of microbial biostimulant with foliar application of PH synergistically increased the marketable fresh yield by 15.5 and 46.7% compared to the Tablet-treated and untreated plants, respectively. The improved crop performance of Tablet + PH application was attributed to a better root system architecture (higher total root length and surface), an improved chlorophyll synthesis and an increase in proline accumulation. Combined application of Tablet and PH could represent an effective strategy to minimize alkalinity and salinity stress in a sustainable way. [ABSTRACT FROM AUTHOR]

Low-pH and aluminum (Al) stresses are the major constraints that limit crop yield in acidic soils. Grafting vegetable elite cultivars onto appropriate rootstocks may represent an effective tool to improve crop tolerance to acidity and Al toxicity. Two greenhouse hydroponic experiments were performed to evaluate growth, yield, biomass production, chlorophyll index, electrolyte leakage, mineral composition, and assimilate partitioning in plant tissues of cucumber plants (Cucumis sativus L. "Ekron") either non-grafted or grafted onto "P360" (Cucurbita maxima Duchesne × Cucurbita moschata Duchesne; E/C) or figleaf gourd (Cucurbita ficifolia Bouché; E/F). Cucumber plants were cultured in pots and supplied with nutrient solutions having different pH and Al concentrations: pH 6, pH 3.5, pH 3.5 + 1.5mM Al, and pH 3.5 + 3mM Al (Experiment 1, 14 days) and pH 6, pH 3.5, and pH 3.5 + 0.75mM Al (Experiment 2, 67 days). Significant depression in shoot and root biomass was observed in response to acidity and Al concentrations, with Al-stress being more phytotoxic than low pH treatment. Significant decrease in yield, shoot, and root biomass, leaf area, SPAD index, N, K, Ca, Mg, Mn, and B concentration in aerial parts (leaves and stems) in response to low pH with more detrimental effects at pH 3.5 + Al. Grafted E/C plants grown under low pH and Al had higher yield, shoot, and root biomass compared to E/F and non-grafted plants. This better crop performance of E/C plants in response to Al stress was related to (i) a reduced translocation of Al from roots to the shoot, (ii) a better shoot and root nutritional status in K, Ca, Mg, Mn, and Zn concentration, (iii) a higher chlorophyll synthesis, as well as (iv) the ability to maintain cell membrane stability and integrity (lower electrolyte leakage). Data provide insight into the role of grafting on Al stress tolerance in cucumber. [ABSTRACT FROM AUTHOR]

BACKGROUND The application of beneficial microorganisms at transplanting can promote rapid transplant establishment (starter effect) for achieving early and high yields. The aim of this study was to evaluate the biostimulant effects of Glomus intraradices BEG72 (G) and Trichoderma atroviride MUCL 45632 (T) alone or in combination on plant growth parameters, yield, chlorophyll index ( SPAD), chlorophyll fluorescence and mineral composition of several vegetable crops. RESULTS The T. atroviride strain was capable of producing siderophores and auxin-like compounds under a wide range of substrate pH conditions (5.5-8.0). The highest shoot, root dry weight, SPAD and chlorophyll fluorescence in lettuce, tomato and zucchini was observed in the G + T combination, followed by a single inoculation of G or T, whereas the lowest values were recorded in the uninoculated plants. Under greenhouse conditions, the shoot dry weight was significantly increased by 167%, 56%, 115%, 68% and 58% in lettuce, melon, pepper, tomato and zucchini, respectively, when supplied with both beneficial microorganisms in comparison with the control. This increase in root and shoot weight was associated with an increased level of nutrient uptake (e.g. P, Mg, Fe, Zn and B). Under open field conditions, the lettuce shoot and root dry weight increased by 61% and 57%, respectively, with biostimulant microorganism application in field conditions. For zucchini, early and total yields were significantly increased by 59% and 15%, respectively, when plants were inoculated with both microorganisms. CONCLUSION The application of the biostimulant tablet containing both G and T can promote transplant establishment and vegetable crop productivity in a sustainable way. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Limited water supply in the Mediterranean region is a major problem in irrigated agriculture. Grafting may enhance drought resistance, plant water use efficiency, and plant growth. An experiment was conducted in two consecutive growing seasons to determine yield, plant growth, fruit quality, leaf gas exchange, water relations, macroelements content in fruits and leaves, and water use efficiency of mini-watermelon plants [Citrullus lanatus (Thunb.) Matsum. ȧind Nakai cv. Ingrid], either ungrafted or grafted onto the commercial rootstock 'PS 1313' (Cucurbita maxima Duchesne x Cucurbita moschata Duchesne), under open field conditions. Irrigation treatments were 1.0, 0.75, and 0.5 evapotranspiration rates. In both years (2006 and 2007), marketable yield decreased linearly in response to an increase in water stress. When averaged over year and irrigation rate, the total and marketable yields were higher by 115% and 61% in grafted than in ungrafted plants, respectively. The fruit quality parameters of grafted mini-watermelons such as fruit dry matter and total soluble solids content were similar in comparison with those of ungrafted plants, whereas titratable acidity, K, and Mg concentrations improved significantly. In both grafting combinations, yield water use efficiency (WUEy) increased under water stress conditions with higher WUE values recorded in grafted than ungrafted plants. The concentration of N, K, and Mg in leaves was higher by 7.4%, 25.6%, and 38.8%, respectively, in grafted than in ungrafted plants. The net assimilation of CO2, stomatal conductance, relative water content, leaf, and osmotic potential decreased under water stress conditions. The sensitivity to water stress was similar between grafted and ungrafted plants, and the higher marketable yield from grafted plants was mainly the result of an improvement in nutritional status and higher CO2 assimilation and water uptake from the soil. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the current work was to determine whether grafting could improve copper (Cu) tolerance of cucumber, and to study the changes induced by the rootstock in the shoot growth at agronomical and physiological levels. A greenhouse experiment was carried out to determine yield, growth, fruit quality, leaf gas exchange, chlorophyll and carotenoids contents, electrolyte leakage, mineral composition and assimilate partitioning of cucumber plants (Cucumis sativus L. cv. ‘Akito’), either ungrafted or grafted onto the commercial rootstock ‘Shintoza’ (Cucurbita maxima Duchesne× Cucurbita moschata Duchesne) and cultured in nutrient film technique (NFT). Plants were supplied with nutrient solutions having three levels of Cu concentration [0.3 (control), 47, or 94μM]. Significant depression of yield, shoot and root biomass production, and fruit quality (low fruit pH, and high Cu content) in Cu treated cucumber plants was observed, and this effect varied as a function of Cu concentration in NFT solution. The relative yield of cucumber decreased by ≈3.4% for each unit of increase in leaf tissue Cu concentrations above the threshold value (7.8μgg−1). At the two higher Cu concentrations (47 and 94μM Cu), the percentages of yield, shoot and root biomass weight reductions were significantly lower in grafted plants in comparison to those of the ungrafted plants. Excessive Cu, especially at 94μM Cu, inhibited photosynthesis, pigment synthesis, and membrane integrity. The Cu-related reductions in net assimilation, stomatal conductance, chlorophyll and carotenoid content were more severe in ungrafted plants in comparison with those grafted on ''Shintoza’. The percentage of electrolyte leakage was significantly higher in ungrafted plants especially those with severe Cu toxicity (94μM Cu). The accumulation of Cu in leaf tissue at 47 and 94μM Cu, with respect to control, were significantly lower in grafted plants (138 and 181%, respectively) in comparison to that of ungrafted plants (about 235 and 392%, respectively). Significant reduction of macro- (N, K, Ca and Mg) and micro-elements (Fe, Mn and Zn) in cucumber leaf tissue was found under moderate and severe Cu stresses especially on ungrafted plants. The improved crop performance of grafted plants was attributed to their strong capacity to inhibit Cu accumulation in the aerial parts and to maintain a better plant nutritional status. [Copyright &y& Elsevier]

Plant-derived protein hydrolysates represent new biostimulant products able to improve crop tolerance to abiotic stresses. The aim of the study was to determine growth, root morphology, SPAD index, chlorophyll fluorescence, leaf mineral composition, and metabolic profiling of greenhouse lettuce either untreated or treated (root or leaf-root application) with a plant-derived protein hydrolysate. For foliar application, plants were sprayed with a solution containing 2.5 ml L −1 of biostimulant, whereas for root application, 100 mL of solution with the same concentration was applied to the growing medium at weekly intervals. Lettuce plants were supplied with two nutrient solutions: non-salt control (1 mM NaCl) or 25 mM NaCl. Salt stress decreased shoot and root dry biomass, SPAD index, chlorophyll fluorescence, leaf mineral composition and increased foliar proline concentration. Root and leaf-root application of the biostimulant increased fresh yield, dry biomass and root dry weight of lettuce under salinity conditions. This was associated with an improvement of plant nitrogen metabolism and an increase of the F v / F m -ratio efficiency in biostimulant-treated plants. Oxidative stress mitigation, increase in osmolytes, changes in sterols and terpenes composition, as well as the less expected increase in glucosinolates were also observed in biostimulant-treated plants grown under saline conditions. The present study proves that the application of plant-derived protein hydrolysate increases plant performance when plants are grown under salinity conditions. The most favorable metabolic profile was obtained when biostimulant was applied to both roots and leaves. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was to determine whether grafting could improve alkalinity tolerance of watermelon, and to study the changes induced by the rootstock in the shoot growth at agronomical, physiological, and biochemical levels. Two greenhouse experiments were carried out to determine growth, net photosynthetic rate, electrolyte leakage, root Fe(III)-chelate reductase (FCR) activity, mineral composition and assimilate partitioning (experiment 1, 2007), and organic acid concentration in root exudates (experiment 2, 2008), of watermelon plants [Citrullus lanatus (Thumb.) Matsum. and Nakai cv. ‘Ingrid’] either ungrafted or grafted onto the four commercial rootstocks: ‘Macis’, ‘Argentario’[Lagenaria siceraria (Mol.) Standl.] and ‘P360’, ‘PS1313’ (Cucurbita maxima Duchesne× Cucurbita moschata Duchesne) grown in a closed-loop system. Plants were supplied with nutrient solutions having two levels of pH (6.0 or 8.1). The high pH nutrient solution had the same basic composition plus an additional of 10mM NaHCO3 and 0.5gL−1 CaCO3. Significant depression of shoot, root biomass production, and leaf macro- (N, P, K, and Mg) and microelements (Fe, Mn, Zn, and Cu) under high pH level was observed in both grafted and ungrafted plants. Increasing the concentration of NaHCO3 from 0 to 10mM in the nutrient solution significantly enhanced FCR activity of root tips to 2.3 times in high pH treatment in comparison to the control. At high pH level, the percentage of shoot biomass weight reduction was significantly lower in plants grafted onto pumpkins rootstocks in comparison to those grafted onto the bottle gourd rootstocks and the ungrafted plants. Moreover, at high pH level, the highest percentage of root biomass weight reduction was recorded in both grafting combinations ‘Ingrid/P360’ and ‘Ingrid/Macis’. The high pH-related reduction in net assimilation was more severe in ungrafted plants in comparison with the grafted ones. The Fe concentration in leaves was significantly higher in plants grafted onto pumpkin rootstocks (avg. 109.5μgg−1) in comparison to that of bottle gourd rootstocks and ungrafted plants (avg. 86.7μgg−1). For plants grafted onto bottle gourd rootstocks and ungrafted plants the high pH level (8.1) in the nutrient solution caused significant decrease in macronutrient leaf concentration especially for P and Mg compared to plants grafted onto pumpkin rootstocks. Increasing the nutrient solution pH from 6.0 to 8.1 increased exudation of organic acids (citric, malic, tartaric and succinic acids). Watermelon plants grafted onto pumpkin rootstocks exuded more citric and malic acids than those grafted onto bottle gourd rootstocks and ungrafted plants especially under bicarbonate-enriched conditions. These results support the hypothesis that uptake of nutrients (e.g. P, Mg, and Fe) from the nutrient solution by pumpkin rootstocks was facilitated by exudation of organic acids from roots. [Copyright &y& Elsevier]

A greenhouse experiment was carried out to determine growth, yield, fruit quality, gas exchange and mineral composition of watermelon plants (Citrullus Lanatus L. 'Tex'), either ungrafted or grafted onto two commercial rootstocks 'Macis' [Lagenaria siceraria (Mol.) Standl.] and 'Ercole" (Cucurbita maxima Duchesne x Cucurbita moschata Duchesne) and cultured in NFT. Plants were supplied with a nutrient solution having an electrical conductivity (EC) of 2.0 or 5.2 dS⋅m--1. The saline nutrient solution had the same basic composition, plus an additional of 29 mM of NaCI. Increased salinity in the nutrient solution decreased total yield. The reduction in total yield in saline treatments compared to control was due to u reduction in the fruit mean mass and not to the number of fruit per plant. Total fruit yield was 81% higher in grafted than in ungrafted plants. The lowest marketable yield recorded on ungrafted plants was associated with a reduction in both fruit mean mass and the number of fruits per plant in comparison to grafted plants. Salinity improved fruit quality in all grafting combinations by increasing dry matter (DM), glucose, fructose, sucrose, and total soluble solid (TSS) content. Nutritional qualities of grafted watermelons such as fruit DM, glucose, fructose, sucrose, and TSS content were similar in comparison to those of ungrafted plant. In all grafting combinations, negative correlations were recorded between Na+ and CI- in the leaf tissue and net assimilation of CO2 Grafting reduced concentrations of sodium, but not chloride, in leaves. However, the sensitivity to salinity was similar between grafted and ungrafted plants and the higher total yield from grafting plants was mainly due to grafting per se. [ABSTRACT FROM AUTHOR]

Highlights: [•] Salinity tolerance of grafted and ungrafted cucumber plants was evaluated. [•] Growth and yield decreased in response to salinity especially in CaCl2 treatment. [•] Grafting improved tolerance to salinity reducing Na and Cl accumulation in shoots. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the current work was to determine whether grafting could improve salinity tolerance of cucumber using two different salt stressors such as NaCl and Na2SO4 with equimolar concentrations, and to study the changes induced by the rootstock in the shoot growth at agronomical and physiological levels. A greenhouse experiment was carried out to determine yield, growth, fruit quality, leaf gas exchange, electrolyte leakage, SPAD, and mineral composition and assimilate partitioning of cucumber plants (Cucumis sativus L. cv. ‘Akito’), either ungrafted or grafted onto the commercial rootstock ‘PS1313’ (Cucurbita maxima Duch.× Cucurbita moschata Duch.) and cultured in quartziferous sand. Plants were supplied with three nutrient solutions: non-salt control, 27mM Na2SO4, or 40mM NaCl. Significant depression of yield, shoot and root biomass production in response to an increase of salinity concentration in the nutrient solution was observed with more detrimental effects with NaCl treatment. The two salt treatments, especially NaCl, inhibited photosynthesis, pigment synthesis, and membrane integrity. Salinity with NaCl and Na2SO4 improved fruit quality in both grafting combinations by increasing fruit dry matter and total soluble solids content. Moreover, at the two salt treatments the percentage of yield and biomass reduction in comparison to control was significantly lower in the plants grafted onto ‘PS1313’ than ungrafted plants, with the highest yield, shoot and root reduction recorded with NaCl in comparison to those recorded with Na2SO4 treatment. Grafted cucumber plants exposed to Na2SO4 were capable of maintaining higher net assimilation rates, higher chlorophyll content (SPAD index), a better nutritional status (higher K, Ca and Mg and lower Na) in the shoot tissues and higher membrane selectivity in comparison with ungrafted ones. The higher crop performance of grafted cucumber recorded with Na2SO4 than with NaCl, was attributed to the inability of the rootstock to restrict Cl− shoot uptake, thus Cl−, which continues passing to the leaves, becomes the more significant toxic component of the saline solution. [Copyright &y& Elsevier]

• Plant-derived biostimulant effect on vegetable transplants quality was explored. • Biostimulat at 4 g/L increases biomass and mineral concentration of transplants. • A reduction of the Chl a / b ratio was noted with the increasing dose of biostimulant. • Biostimulant application in the substrate improves the transplant performances. The urgent need to increase sustainable crop production has pushed the agricultural sector towards methods based on natural products such as biostimulants. The nursery industry holds strategic importance for modern horticulture because only "high quality" seedlings can guarantee productive success. The aim of our research was to assess the effects of a microgranule plant-derived biostimulant added to the transplants' substrate. Biometric parameters, mineral composition, total chlorophylls, carotenoids, and total phenols content of eggplant (Solanum melongena L., cv. Mirabelle F1), pepper (Capsicum annuum L., cv. Tarquinio F1), and tomato (Solanum lycopersicum L., cv. Taylor F1) at four different biostimulant doses (0.5, 1, 2, and 4 g L−1) were evaluated. Compared to the untreated control, the use of the highest dose of microgranule biostimulant (4.0 g L−1) increased shoot dry weight by 73%, 61%, and 33% and root dry weight by 37%, 34%, 36%, for eggplant, pepper, and tomato, respectively. Similarly, the nitrogen and potassium contents of eggplant, pepper, and tomato plants were positively affected by biostimulant application. Total chlorophylls content and carotenoids were significantly affected only in tomato leaves with the 2.0 and 4.0 g L−1 doses while no significant differences for total phenols were recorded in transplant leaves of tested vegetable crops. Chlorophyll a / b decreased in eggplant and pepper with increasing microgranular-based PHs rates, indicating a greater accumulation of chlorophyll b than chlorophyll a. Our results show that microgranule biostimulant application directly mixed in the substrate can improve the quali-quantitative traits of nursery seedlings while reducing the excessive use of fertilizers and concomitantly producing vigorous seedlings potentially capable of overcoming easily transplant stress. [ABSTRACT FROM AUTHOR]