Negative Effects Of Drought Stress Research Articles

Abscisic acid improves drought resilience, growth, physio-biochemical and quality attributes in wheat (Triticum aestivum L.) at critical growth stages

Wheat is an important staple crop not only in Pakistan but all over the globe. Although the area dedicated to wheat cultivation expands annually, the quantity of wheat harvested is declining due to various biotic and abiotic factors. Global wheat production and output have suffered as a result of the drought, which is largely driven by a lack of water and environmental factors. Organic fertilizers have been shown to reduce the severity of drought. The current research was conducted in semi-arid climates to mitigate the negative effects of drought on wheat during its critical tillering (DTS), flowering (DFS), and grain filling (DGFS) stages through the application of three different abscisic acid treatments: ABA0 (0 mgL−1) control, ABA1 (100 mgL−1) and ABA2 (200 mgL−1). Wheat growth and yield characteristics were severely harmed by drought stress across all critical development stages, with the DGFS stage being particularly vulnerable and leading to a considerable loss in yield. Plant height was increased by 24.25%, the number of fertile tillers by 25.66%, spike length by 17.24%, the number of spikelets per spike by 16.68%, grain count per spike by 11.98%, thousand-grain weight by 14.34%, grain yield by 26.93% and biological yield by 14.55% when abscisic acid (ABA) was applied instead of the control treatment. Moreover, ABA2 increased the more physiological indices (water use efficiency (36.12%), stomatal conductance (44.23%), chlorophyll a (24.5%), chlorophyll b (29.8%), transpiration rate (23.03%), photosynthetic rate (24.84%), electrolyte leakage (− 38.76%) hydrogen peroxide (− 18.09%) superoxide dismutase (15.3%), catalase (20.8%), peroxidase (− 18.09%), and malondialdehyde (− 13.7%)) of drought-stressed wheat as compared to other treatments. In the case of N, P, and K contents in grain were maximally improved with the application of ABA2. Through the use of principal component analysis, we were able to correlate our results across scales and provide an explanation for the observed effects of ABA on wheat growth and production under arid conditions. Overall, ABA application at a rate of 200 mgL−1 is an effective technique to boost wheat grain output by mitigating the negative effects of drought stress.

The impact of chitosan nanoparticles on seedling and germination attributes and enzymatic activity of guar (Cyamopsis tetragonoloba L.) under osmotic stress

This research was conducted to examine the effects of nano chitosan particles on seed germination and seedling growth of guar (Cyamopsis tetragonoloba L.) under osmotic stress conditions. This experiment was conducted in a factorial layout based on a completely randomized design with two factors and four replications. The experimental factors included: osmotic stress at five levels (0, -3, -6, -9 and -12 bar) and seed priming with nano chitosan particles at five concentrations (0, 50, 100, 200, and 300 ppm). The evaluated parameters in this study were alometric traits and enzymatic activities including proline, catalase, ascorbate peroxidase, superoxide dismutase, and total soluble sugar, as well as the content of chlorophyll a, b, and carotenoids. The results indicated the significant effect of most of the studied quantitative and qualitative traits. The highest values of seedling, plumule and radicle length (48.20, 17.79 and 30.15 mm, respectively), and the fresh weight of seedlings and plumule (0.9743 and 0.9192 g, respectively) were observed at a concentration of 200 ppm of chitosan nanoparticles. The highest amount of all studied parameters observed under non-stress conditions (control), and the lowest values of them obtained in -12 bar of osmotic stress. Furthermore, by increasing of osmotic stress levels, germination percentage and rate and seed vigor showed a decreasing trend about 56, 83 and 95% compared to the control. Besed on the interaction effects, the maximum values of seedling and plumule length were achieved with the application of 200 ppm chitosan nanoparticles in combination with no osmotic stress. Under non-osmotic conditions, concentrations of 300, 100, and 200 ppm chitosan led to the highest values of germination percentage and rate and seed vigor, respectively. Additionally, the highest percentage of normal seedlings (94%) and the lowest percentage of abnormal seedlings (zero) were obtained under the application of 200 ppm of nano chitosan and no osmotic stress. In relation to qualitative traits, the lowest values of soluble sugar and proline were obtained at the osmotic level of -12 bar. Moreover, the application of 200 ppm of nano chitosan and -6 bar of osmotic stress resulted in the highest levels of catalase, superoxide dismutase, ascorbate peroxidase, chlorophyll a, b, and carotenoids. As a whole, the results of the study demonstrated that seed priming with chitosan nanoparticles can reduce the negative effects of drought stress on guar seedlings. In addition, application of 200 ppm of this substance was the most suitable treatments that improve most quantitative and qualitative indices of guar. Keywords: Enzymatic activity, Nano particles, Priming, Seed structure.

Precise partial root-zone irrigation technique and potassium-zinc fertigation management improve maize physio-biochemical responses, yield, and water use in arid climate

BackgroundTo optimize irrigation water use and productivity, understanding the interactions between plants, irrigation techniques, and fertilization practices is crucial. Therefore, the experiment aims to assess the effectiveness of two application methods of potassium humate combined with chelated zinc under partial root-zone drip irrigation techniques on maize nutrient uptake, yield, and irrigation water use efficiency across two irrigation levels.MethodsOpen-field experiments were carried out in two summer seasons of 2021 and 2022 under alternate and fixed partial root-zone drip irrigation techniques to investigate their impacts at two irrigation levels and applied foliar and soil applications of potassium humate or chelated zinc in a sole and combinations on maize.ResultsDeficit irrigation significantly increased hydrogen peroxide levels and decreased proline, antioxidant enzymes, carbohydrate, chlorophyll (a + b), and nutrient uptake in both partial root-zone techniques. The implementation of combined soil application of potassium humate and chelated zinc under drought conditions on maize led to varying impacts on antioxidant enzymes and nutritional status, depending on the type of partial root-zone technique. Meanwhile, the results showed that fixed partial root-zone irrigation diminished the negative effects of drought stress by enhancing phosphorus uptake (53.8%), potassium uptake (59.2%), proline (74.4%) and catalase (75%); compared to the control. These enhancements may contribute to improving the defense system of maize plants in such conditions. On the other hand, the same previous treatments under alternate partial root zone modified the defense mechanism of plants and improved the contents of peroxidase, superoxide dismutase, and the uptake of magnesium, zinc, and iron by 81.3%, 82.3%, 85.1%, 56.9%, and 80.2%, respectively.ConclusionsAdopting 75% of the irrigation requirements and treating maize plants with the soil application of 3 g l−1 potassium humate combined with 1.25 kg ha−1 chelated zinc under alternate partial root-zone technique, resulted in the maximum root length, leaf water content, chlorophyll content, yield, and irrigation water use efficiency.

Surface modified ZnO NPs by betaine and proline build up tomato plants against drought stress and increase fruit nutritional quality

Drought stress is a serious challenge for global food production. Nanofertilizers and nanocomposites cope with such environmental stresses and also increase nutritional contents of fruits. An in vitro experiment was designed to use Zinc Oxide Nanoparticles (ZnO NPs) primed with Proline and Betaine (ZnOP and ZnOBt NPs) at 50 and 100 mg/kg soil against drought stress in Tomato (Solanum lycopersicum) plants. Plant morphological, biochemical, and fruit nutritional quality were accessed. Maximum plant height was observed under the treatment of ZnOP50 (1.09 m) and ZnO 100 (1.06 m). ZnOP and ZnOBt also improved the chlorophyll content up to 86% and 87.16%, respectively. Application of ZnOP NPs also demonstrated maximum tomato yield (204 g tomato/plant) followed by ZnO NPs and ZnOBt NPs. Nanocomposites decreased phenolics and flavonoids contents in drought stressed plants demonstrating the mitigation of oxidative stress. Nanofertilizer also increased the concentration of phenolics and flavonoids in fruits that increased the nutritional contents. Furthermore a significant accumulation of betaine, proline, and lycopene in fruits on nanocomposite treatment made it nutritional and healthy. Lycopene content increased up to 2.01% and 1.23% in presence of ZnOP50 and ZnOP100, respectively. These outcomes validate that drought stress in plant can be reduced by accumulation of different phytochemicals and quenching oxidative stress. The study deems that nano zinc carrying osmoregulators can greatly reduce the negative effects of drought stress and increase nutritional quality of tomato fruits.

Mitigation of drought stress effects on alfalfa (Medicago sativa L.) callus through CaO nanoparticles and graphene oxide in tissue culture conditions

Drought stress poses a significant threat to fertile soils worldwide, triggering profound physiological, biochemical, and molecular changes in plants that adversely impact agricultural productivity. This study explores the potential of nanotechnology, specifically Calcium Oxide Nanoparticles (CaO NPs) and Graphene Oxide (GO), to ameliorate the negative effects of drought stress on two distinct alfalfa ecotypes. Seeds from Erzurum and Konya regions were regenerated in the Murashige and Skoog (MS) medium, and ensuing callus formation was induced through 1 mg L−1 2,4-D and 1 mg L−1 kinetin MS medium. The callus samples underwent a one-month treatment with varying concentrations of mannitol (50 and 100 mM), CaO NPs, and GO (0.5 and 1.5 ppm). Results revealed a decrease in dry/wet weight with increasing mannitol concentration, contrasting with an increase in weight under CaO NPs and GO treatment. Proline, DNSA, MDA, and H2O2 exhibited proportional increases under drought stress, while CaO NPs and GO treatments mitigated these effects. Physiological and biochemical analyses identified optimal conditions for Erzurum as 50 mM mannitol/2 CaO NPs/0.5 ppm GO, and for Konya as 50 mM mannitol/0.5 ppm GO. Gene expression analysis indicated up-regulation of mtr-miR159 and mtr-miR393 with heightened drought stress, with down-regulation observed in CaO NPs and GO treatments. Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) confirmed Ca2+ accumulation in alfalfa tissues. In conclusion, CaO NPs and GO treatments exhibited a significant reduction in the adverse effects of drought stress on alfalfa callus under tissue culture conditions. This research sheds light on the potential of nanotechnological interventions to alleviate the impact of environmental stressors on crop plants, opening avenues for sustainable agriculture in the face of changing climatic conditions. Further investigations are warranted to elucidate the underlying mechanisms and scalability of these findings for field applications.

Drought priming enhances wheat grain starch and protein quality under drought stress during grain filling

The impact of drought stress on crop yield and quality is substantial. Drought priming during the early growth stage of plants has been shown to improve tolerance to drought stress during the reproductive stage, although its effects on grain quality remains elusive. This study aimed to investigate the influence of drought priming on starch and protein levels in grains under drought stress during grain filling. Our results reveal that drought stress results in a reduction in starch content and its constituents, while simultaneously increasing glutenin macropolymers and protein fractons. Notably, drought primed plants under drought stress (PD) exhibit mitigated declines in starch content and its components, leading to improvements in starch swelling power and pasting properties. Additionally, PD results in a slight increase in protein fractions, limiting the overall rise in total protein content compared to drought stress alone. Collectively, our study underscores the efficacyof drought priming as a strategy to counteract the negative effects of drought stress on grain quality, particularly by minimizing starch losses and restraining protein content elevation.

Exogenous spermidine alleviates negative effects of drought stress on antioxidant enzyme activity, cell cycle regulation, endogenous polyamines and total protein amount in Hordeum vulgare L.

Exogenous spermidine alleviates negative effects of drought stress on antioxidant enzyme activity, cell cycle regulation, endogenous polyamines and total protein amount in Hordeum vulgare L.

Impacts of Various Calcium Concentrations on the Biochemical Characteristics of Corn (Zea mays L.) Seedlings in Drought Conditions

ABSTRACT In recent years, there has been a significant decrease in corn production and quality due to drought. Ca applications are thought to be effective in eliminating this negative effect of drought. The research was conducted in a climatic chamber using a completely randomized experimental design. Four Ca doses were used in this study as research factors. In the study, increases in malondialdehyde, catalase activity, and superoxide dismutase levels, as well as leaf proportional water content, membrane damage index, Ca, and potassium contents, were examined. As a result of the research; leaf proportional water content was 55.633–72.103%, membrane damage index 44.540–71.643%, K content 1.967–2.733%, Ca content 0.243–0.497%, malondialdehyde activity 0.090–0.114 nmol g−1 FW, catalase activity 0.015–0.043 nmol g−1 FW and superoxide dismutase varied between 0.011 and 0.027 unit g−1 FW. Drought stress has negative effects on yield and quality properties in crop production. It has been determined that these negative impacts vary depending on the genetic structure of the plants as well as the presence of regulatory elements such as Ca. In this research, it was determined that Ca fertilization under drought stress caused a decrease in K content and some enzymatic activities such as MDI, MDA, CAT, and SOD, and an increase in LWC and Ca contents in corn seedlings. As a result, it is concluded that the applied Ca doses reduced the negative effects of drought. In conclusion, the 400 mg L−1 Ca application is recommended for reducing the negative effects of drought stress.

Water Use Strategies and Shoot and Root Traits of High-Yielding Winter Wheat Cultivars under Different Water Supply Conditions

Drought is the most important factor limiting winter wheat yield in the North China Plain (NCP). Choosing high-yielding cultivars is an important measure to minimize the negative effects of drought stress. Field studies were conducted with 10 cultivars in the 2020–2022 seasons under three irrigation treatments (I0, without irrigation; I1, irrigated at jointing stage; I2, irrigated at jointing and anthesis stages) in the NCP to examine the water use strategies and root and shoot traits of high-yielding cultivars under different water supply conditions. The results showed that yield variation among cultivars was 21.2–24.6%, 23.7–25.9% and 11.6–15.3% for the I0, I1 and I2 treatments, respectively. Under water deficit conditions (I0 and I1), high-yielding cultivars reduced water use during vegetative stages and increased soil water use during reproductive stages, especially water use from deeper soil layers. Those cultivars with higher root length density (RLD) in deep soil layers exhibited higher water uptake. Each additional millimeter of water used after anthesis from the 100–200 cm soil layers increased grain yield by 23.6–29.6 kg/ha and 16.4–28.5 kg/ha under I0 and I1, respectively. This water use strategy enhanced dry matter accumulation after anthesis, decreased canopy temperature (CT) and increased relative leaf water contents (RLWC), which ultimately improved grain yield. For winter wheat grown under I2, cultivars that decreased water use after anthesis had higher water productivity (WP). Root length (RL), root weight (RW) and root:shoot ratio were each negatively correlated with grain yield, while above-ground biomass was positively correlated with grain yield. Therefore, higher dry matter accumulation and smaller root systems are two important traits of high-yielding cultivars under sufficient water supply conditions (I2) in the NCP.

Impact of ascorbic acid-rich phyto-extracts on growth, yield and physio-biochemistry of okra [Abelmoschus esculentus (L.) Moench.] subjected to drought stress

To overcome the negative effects of drought stress by exogenous application of natural [lemon juice (LJ) and orange juice (OJ)] and synthetic ascorbic acid (AsA) as sources of potential antioxidants was assessed in okra (A. esculentus) under field conditions. The experiment comprised of two cultivars (Sabz Pari and Bhindi Sanwali) those were subjected to different irrigation regimes including control (12 irrigations) as well as water deficit regimes such as D1 (eight irrigations) and D2 (six irrigations). The plants were sprayed with synthetic AsA (150 mg L-1), 50 % LJ and 50 % OJ to both control and water stressed plants after 30 days of seed germination. Foliar applied AsA obtained from varied sources significantly increased the plant biomass, yield characteristics and leaf photosynthetic pigments, total soluble proteins, proline, AsA, total amino acids, total phenolics, total soluble sugars, and activities of POD, CAT and SOD enzymes in okra plants under varying irrigations. Although, in contrast different AsA sources minimized the accumulation of H2O2 and MDA contents in okra plants. In conclusions, LJ and OJ (both 50 %) proved to be more effective than the synthetic AsA (150 mg L-1) in enhancing yield production, plant biomass and different physio-biochemical traits of okra plants subjected to varying water stress levels. Thus, a better organic source of AsA both LJ and OJ may be suggested to overcome the negative influence of water deficiency in plants.

A novel approach for reducing water stress on sunflower plants by using medicinal plant extracts rather than artificial growth regulators

One of the most significant physiological stressors that negatively impact plants in numerous vital areas of their growth and metabolism is water stress. This study estimates the effects of natural bio-stimulants (Origanum majorana, Nigella sativa and Curcurma longa) extracts for the first time, on water stress of sunflower plant in comparison with synthetic growth regulators (glycein betaine, proline, indole acetic acid, benzyl adenine and ascorbic acid). Water stress appeared to decrease of lengths, fresh and dry weights of shoot and root. Also caused a significant drop in chlorophylls and carotenoids. Foliar application of these synthetic and natural growth regulators significantly decreased the negative effects of drought stress on all studied morphological parameters and pigment contents of sunflower. HPLC analysis of bio-stimulants appeared six phenolic acids, one phenol and two flavonoids were found in all natural extracts. Gallic, rosmarinic, caffeic, syringic acids and kaempferol are the major phenolic compounds (more than 1000 µg/g) detected in Origanum majorana. While gallic acid, hesperetin and ferulic acid are the major phenolic compounds (more than 1000 µg/g) present in Curcurma longa. Chlorogenic acid, gallic acid, catechin, pyro catechol, coffeic acid and rutin are the dominant phenolic compounds present in Nigella sativa. The Nigella sativa treatment showed the highest decrease in proline levels. This may be due to the high concentration of caffeic acid (2406.97 g/g). The Origanum majorana treatment had the highest levels of chl. a and carotenoid contents, which rose by about 32% and 72%, respectively, compared to the stress-treated plant. The highly decrease in catalase activity, which is considered as most important indicator to water stress, appeared in Origanum majorana treatment. We suggest the use of these natural extracts as an alternative way, which appeared a significant increase in growth and biochemical near to synthetic regulators in the treatment of water stress due to the fact that these extracts contain many important phenolic compounds that have a role in the treatment of water stress.

Unraveling the effects of melatonin on drought-stressed pear rootstocks: A comparative analysis of Dargazi and Pyrodwarf

Drought stress is known as one of the major challenges in most fruit-growing areas. This research aimed to investigate the amelioration effect of pre-drought exogenous melatonin application on the physiological and biochemical response of `Dargazi’ seedling and `Pyrodwarf’ clonal pear rootstocks, grown under water stress and controlled greenhouse conditions. Drought stress was applied by withholding irrigation water for 40 days on one-year-old un-grafted seedlings and clonal pear rootstocks. Gas exchange, chlorophyll content, relative water content, lipid peroxidation, and enzyme antioxidant activity were examined. Pre-drought treatment of melatonin significantly increased drought tolerance, successfully recovered the lost growth and considerably improved photosynthetic efficiency. The adverse effect of drought stress was ameliorated by melatonin through the possible osmotic adjustment such as the increase of proline (102 and 92 g/g FW for `Dargazi' and `Pyrodwarf' respectively) and soluble sugars as well as the improvement of the antioxidative defense system through the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX). The `Dargazi’ seedling rootstock showed better tolerance to drought stress with higher photosynthesis, leaf water content, chlorophyll content, antioxidant enzyme activity, lower lipid peroxidation, and H2O2 generation than the Pyrodwarf clonal rootstock. Also, melatonin ameliorated the negative effect of water stress on photosynthesis and growth parameters through the possible inducing osmotic adjustment and anti-oxidative system under the severe drought stress condition on pear rootstocks. SOD, APX, POD, and CAT activities in Dargazi rootstock were significantly higher than those in control plants by 76.1 %, 34.9 %, 20.93 %, and 124.42 % respectively. Similarly, SOD, APX, POD, and CAT in Pyrodwarf pear rootstock increased in enzyme activities by 56.92 %, 24.37 %, 35.53 %, and 259.52 %, respectively. It is concluded that melatonin application as a pre-drought treatment mitigates the negative effects of drought stress in both rootstocks and the Dargazi rootstock exhibits remarkable resilience to drought stress.

Enhancing crop resilience through thiamine: implications for sustainable agriculture in drought-stressed radish

During 21st century, abiotic stress has adversely affected the agriculture crop production around the globe. Keeping in view the food requirement under water shortage condition, a study was planned to investigate the effect of thiamine application on radish crop under drought stress conditions on plant. For study purpose, two varieties of locally available radish (‘Early-Milo’ and ‘Laal-Pari’) were grown with normal water application as well as thiamine (100 mg L-1) application while maintaining a stress condition (60% field capacity). Increasing water deficit stress linearly reduced plant growth, yield and biomass in both varieties by reducing water use efficiency, while significantly enhanced these attributes with thiamine application. Thiamine application under drought stress exerted significant impacts on physiological attributes in both varieties, including enhanced osmolytic attribute in drought conditions and improvements in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), H2O2, and malondialdehyde (MDA) activities in plant leaves. Antioxidant and osmoprotectant upregulation positively linked to radish crop's drought tolerance. Moreover, PCA and heatmap analysis revealed a significant interdependence among various traits and interconnected in determining the crop's capacity to sustain growth under conditions of drought stress. In crux, thiamine application conclusively enhances radish growth, yield, biomass, physio-chemical and osmolytic attributes, ionic composition and enzymatic antioxidant potential. Therefore, it is recommended to consider the application of thiamine in commercial agriculture practices to mitigate the negative effects of drought stress on radish crop production.

Impacts of biostimulants on crop yield and biological activity under drought conditions

AbstractIntroductionBiostimulants are proposed to have a role in sustainable food production and are being increasingly used strategies to limit the negative effects of drought stress on crop yield and soil health. However, how different biostimulants used alone, or in combination with conventional management approaches affect soil health and crop yield under drought in different soils is not well understood. Here we conducted a glasshouse experiment to investigate this.Materials and MethodsTwo soil types from fields maintained under intensive (IM) and extensive (EM) management practices were used with two commercial biostimulants [Universal Natural Plant food (UNP) and Converte Seed Primer (CSP)] on soil microbial populations and crop yield (lettuce) under well‐watered and drought stressed conditions. We examined the activity and biomass of soil microorganisms as well as seed germination and root and shoot biomass to examine the effect of application of biostimulants on parameters of soil health and crop yield.ResultsBiostimulants generally increased crop yield, basal soil respiration and microbial biomass, with effects stronger in EM soils than in IM soils, but effects on soil enzyme activities were variable. The combined use of biostimulant and inorganic fertiliser negated the benefits of the biostimulant on soil biological properties in some cases. Nevertheless, effects of biostimulants had a positive impact on crop yield with the combined use of soil‐applied and seed applied biostimulants have the greatest impact on plant biomass and also conferring some resistance in both soil microbial communities and plant growth to drought.ConclusionsWhile biomass and activity of the microbial community and plant growth responses to biostimulant additions are both soil and biostimulant dependent, their combined use has potential to aid both plants and maintain promote microbial activity under of drought, compared to conventional fertiliser treatments in extensively managed soils.

Selenium nanoparticles conferred drought tolerance in tomato plants by altering the transcription pattern of microRNA-172 (miR-172), bZIP, and CRTISO genes, upregulating the antioxidant system, and stimulating secondary metabolism.

Drought stress is one of the major limiting factors for the production of tomato in Iran. In this study, the efficiency of selenate and Se nanoparticle (SeNP) foliar application on tomato plants was assessed to vestigate mitigating the risk associated with water-deficit conditions. Tomato plants were treated with SeNPs at the concentrations of 0 and 4mg L-1; after the third sprays, the plants were exposed to water-deficit conditions. The foliar spraying with SeNPs not only improved growth, yield, and developmental switch to the flowering phase but also noticeably mitigated the detrimental risk associated with the water-deficit conditions. Gene expression experiments showed a slight increase in expression of microRNA-172 (miR-172) in the SeNP-treated plants in normal irrigation, whereas miR-172 displayed a downregulation trend in response to drought stress. The bZIP transcription factor and CRTISO genes were upregulated following the SeNP and drought treatments. Drought stress significantly increased the H2O2 accumulation that is mitigated with SeNPs. The foliar spraying with Se or SeNPs shared a similar trend to alleviate the negative effect of drought stress on the membrane integrity. The applied supplements also conferred drought tolerance through noticeable improvements in the non-enzymatic (ascorbate and glutathione) and enzymatic (catalase and peroxidase) antioxidants. The SeNP-mediated improvement in drought stress tolerance correlated significantly with increases in the activity of phenylalanine ammonia-lyase, proline, non-protein thiols, and flavonoid concentrations. SeNPs also improved the fruit quality regarding K, Mg, Fe, and Se concentrations. It was concluded that foliar spraying with SeNPs could mitigate the detrimental risk associated with the water-deficit conditions.

The impact of the application of compochar on soil moisture, stress, yield and nutritional properties of legumes under drought stress

Nowadays, when climate change is becoming more and more evident, drought stress plays a very important role, including in agriculture. The increasing number of years with extreme temperatures in the Czech Republic has a negative impact on agricultural production, among other things. Therefore, ways are being sought to reduce these negative impacts. One of them may be the use of compochar (a mixture of compost and biochar) to improve water retention in the soil.The effect of compochar addition on soil properties and crop yield was tested under conditions simulating severe drought stress (greenhouse experiments) compared to normal conditions (field experiments). The aim was to find the most suitable ratio of compochar addition that would reduce the negative effects of drought stress on the yield and quality of peas and beans. Tested soil was only able to retain water between 0.03 and 0.18 cm3/cm3, while the compochar itself retained between 0.12 and 0.32 cm3 cm−3. Three substrate variants were tested by varying the amount of compochar (10, 30 and 50 % v/v) in the soil, and all three substrates showed a similar water content between 0.03 and 0.21 cm3 cm−3 depending on the planted crop and week of cultivation. No apparent stress was observed in crops planted in 100 % compochar. Nevertheless, in general, the trend of chlorophyll a/b ratio increased with increasing amounts of compochar in the soil, indicating stress. Yield increased by approximately 50 % for both test crops when 30 % compochar was used as substrate. The flavonoid content in beans was between 410 and 500 μg CE g−1 DW and in peas was approximately 300 μg CE g−1 DW. The results showed that the utilization of compochar had no effect on either total phenol content, flavonoid content or antioxidant capacity.The combination of compochar with soil (30 %) was found to positively affect the (i) soil moisture, (ii) crop yield, and (iii) nutritional properties of peas and beans and (iv) the ability of plants to withstand drought stress.

Sole and combined foliar application of silicon and putrescine alleviates the negative effects of drought stress in maize by modulating the morpho-physiological and antioxidant defence mechanisms

Sole and combined foliar application of silicon and putrescine alleviates the negative effects of drought stress in maize by modulating the morpho-physiological and antioxidant defence mechanisms

Effect of spraying iron, zinc and using superabsorbent on grain yield and some biochemical properties of maize under drought stress

Nutrients such as iron and zinc play a vital role in controlling the negative effects of drought stress through the synthesis of enzymes, maintenance of cell membrane, and activation of antioxidant defense system. Due to these biochemical properties, an experiment was conducted to evaluate effect of spraying iron, zinc and using superabsorbent on grain yield and some of biochemical properties of maize under drought stress in a randomized complete block design in Shooshtar city during the years 2017–2018. The experimental treatments included three levels of drought stress (Irrigation after 30%, 40% and 50% evaporation). Sub-plots consisted of superabsorbent polymer at two levels (control and 200 kg/ha) and combination of iron and zinc (control, iron, zinc, and iron-zinc). The results showed that drought stress affected chlorophyll, proline, iron grain concentration, nitrogen percent, grain protein and grain yield. Drought stress caused a significant reduction in yield. The percentage of grain protein was significantly increased in irrigation treatment at 50% of farming capacity. The highest grain yield and chlorophyll index was observed in 30% irrigation treatment. Spraying iron and zinc significantly increased the grain yield, chlorophyll index, iron, and zinc concentrations. Furthermore, drought stress and superabsorbent interacted significantly on grain yield. The interaction among drought stress and superabsorbent elements had significant effects on zinc and iron concentration. The present study suggests that using 200 kg/ha superabsorbent polymer and spraying iron and zinc under the 40% post-discharge irrigation may improve grain yield and biochemical features of maize.

Trehalose alleviates the inhibition of adventitious root formation caused by drought stress in cucumber through regulating ROS metabolism and activating trehalose and plant hormone biosynthesis

Trehalose (Tre) plays a vital role in response to drought stress in plants but its regulatory mechanism remains unclear. Here, this study explores the mechanism of re-regulated drought tolerance during cucumber adventitious root formation. Our results indicate that 2 mM Tre displays remarkable drought alleviation in the aspect of root number, root length, fresh weight, and dry weight. Under drought stress, Tre could inhibit greatly the MDA, H2O2, and O2− accumulation, enhance obviously the activities of SOD, POD, and CAT enzymes and up-regulate significantly the transcript levels of SOD, POD, and CAT genes. Furthermore, Tre treatment also promotes Tre metabolism during drought stress: significantly increases starch and Tre contents and decreases glucose content, the biosynthesis enzymatic activity of the Tre metabolic pathway including TPS and TPP are enhanced and the activity of degradation enzyme THL is decreased, and corresponding genes TPS1, TPS2, TPPA, and TPPB are up-regulated. Tre significantly reversed the decrease caused by PEG in IAA, ethylene, ABA, and BR contents and the increase caused by PEG in GA3 and KT contents. Collectively, Tre appears to be the effective treatment in counteracting the negative effects of drought stress during adventitious root formation by regulating ROS, Tre metabolisms and plant hormones.

Alleviation role of exogenous cadaverine on cell cycle, endogenous polyamines amounts and biochemical enzyme changes in barley seedlings under drought stress

Cadaverine (Cad), which has an independent synthesis pathway compared to other polyamine (PA) types, contributes to the health of plants by regulating plant growth and development, abiotic stress tolerance and antioxidant defense mechanisms. In this work, experiments were carried out to understand the effects of exogenous Cad (10 µM) application under drought stress (%22 PEG 6000) and without stress on cell cycle, total protein content, endogenous PA levels, and biochemical enzyme activities in barley (Hordeum vulgare cv. Burakbey) considering the potential of Cad to stimulate the drought-related tolerance system. Cad application in a stress-free environment showed an effect almost like low-impact drought stress, causing changes in all parameters examined compared to samples grown in distilled water environment (Control). The results clearly show that Cad applied against the negative effects of drought stress on all parameters creates a drought resistance mechanism of the plant. Accordingly, Cad applied together with drought stress increased the density of cells in the cell cycle (G1–S and S–G2 phases) and the amount of endogenous (spermidine 10% and spermine 40%) PAs. In addition, while superoxide dismutase (SOD) (5%), (CAT) (55%) and ascorbate peroxidase (APX) (18%) enzyme levels increased, a stress response mechanism occurred due to the decrease in total protein content (20%) and malondialdehyde (MDA) (80%). As a result, exogenous application of 10 µM Cad showed that it reduced the negative effects of drought stress on endogenous PA amounts, cell division and biochemical activities in barley.