Drought and low amounts of mineral nutrients in the soil are the two leading global constraints in arid and semiarid regions. Their detrimental effects on soils and crops can be alleviated by applying controlled release and biodegradable fertilizers to better and sustain the crops. On a global scale, spinach (Spinacia oleracea L.) is an essential leafy green vegetable that is biologically considered a reliable source of essential nutrients and minerals for human health. A comprehensive approach is needed to manage water stress to mitigate the impacts of stress-caused damage and to examine this for better and increased plant production. An experiment was conducted using potassium-nitrate-containing chitosan/montmorillonite microparticles (150 mg) under mild and severe drought stress (MDS: 50% and SDS: 35% FC, respectively). The treatments include control (no KNO3 and 70% FC as normal irrigation (NI)), KNO3 + NI, 50% FC as mild drought stress (MDS), KNO3 + MDS, 35% FC as severe drought stress (SDS) and KNO3 + SDS. Results revealed that drought stress decreased all studied physiological parameters and increased oxidative stress indicators in spinach. Applying KN significantly increased root (122%) and shoot length (4%), shoot fresh weight (32%) and shoot dry weight (71%), chlorophyll a (88%), carotenoids (39%), total soluble proteins (50%), soluble sugars (51%), potassium (80%), and phosphorous (32%) concentrations over No KN at severe drought. While stress indicators, like glycine betaine, malondialdehyde, hydrogen peroxide, electrolyte leakage, peroxidase, superoxide dismutase, and ascorbic acid levels, were increased in stress. Treatment KN was proved efficient and effective in improving spinach physiological status in both MDS and SDS.

Among abiotic stresses salinity is one of the serious threats for food security worldwide. Sunflower is ranked 5 th among crops grown for food security and being moderately salt tolerant is a better choice for growing on saline soil. Application of various compounds including vitamin E might be a beneficial technique for improving growth in plants under saline conditions. A pot experiment was conducted to explore the role of alpha tocopherol seed treatment for inducing salt tolerance in sunflower. Seeds of two sunflower cultivars (FH-572 and FH-621) were soaked for 16 h in four levels of alpha tocopherol i.e. control (distilled water), 100, 200, 300 mg L-1 and two levels of NaCl salt (0 and 120 mM) were applied with full strength Hoagland's solution 35 days after seed sowing. Salt stress caused significant decrease in shoot and root fresh weight, leaf relative water content and inhibition in shoot length. Salinity stress increased leaf turgor potential and had non-significant effect on photosynthetic pigments, osmotic potential and gas exchange characteristics. Seed treatment with α-tocopherol considerably increased shoot and root fresh weight, shoot length, net CO2 assimilation rate, stomatal conductance (gs) and water use efficiency; however, it showed non-significant effect on photosynthetic pigments, leaf water relation parameters and transpiration rate. Alpha tocopherol, 100 and 300 mg L-1 levels were effective in ameliorating the negative impact of salt stress in cv. FH-572 and cv. FH-621, respectively. Results depicts great varietal difference in salinity tolerance and cultivar FH-621 performed better than cv. FH-572 under salinity stress.

Less nutrient availability and drought stress are some serious concerns of agriculture. Both biotic and abiotic stress factors have the potential to limit crop productivity. However, several organic extracts obtained from moringa leaves may induce immunity in plants under nutritional and drought stress for increasing their survival. Additionally, some rhizobacterial strains have the ability to enhance root growth for better nutrient and water uptake in stress conditions. To cover the knowledge gap on the interactive effects of beneficial rhizobacteria and moringa leaf extracts (MLEs), this study was conducted. The aim of this experimental study was to investigate the effectiveness of sole and combined use of rhizobacteria and MLEs against nutritional and drought stress in wheat. Nitrogen-fixing bacteria Pseudomonas aeruginosa (Pa) (108 CFU ml–1) was inoculated to wheat plants with and without foliar-applied MLEs at two different concentrations (MLE 1 = 1:15 v/v and MLE 2 = 1:30 v/v) twice at 25 and 35 days after seed sowing (50 ml per plant) after the establishment of drought stress. Results revealed that Pa + MLE 2 significantly increased fresh weight (FW), dry weight (DW), lengths of roots and shoot and photosynthetic contents of wheat. A significant enhancement in total soluble sugars, total soluble proteins, calcium, potassium, phosphate, and nitrate contents validated the efficacious effect of Pa + MLE 2 over control-treated plants. Significant decrease in sodium, proline, glycine betaine, electrolyte leakage, malondialdehyde, hydrogen peroxide, superoxide dismutase (SOD), and peroxide (POD) concentrations in wheat cultivated under drought stress conditions also represents the imperative role of Pa + MLE 2 over control. In conclusion, Pa + MLE 2 can alleviate nutritional stress and drought effects in wheat. More research in this field is required to proclaim Pa + MLE 2 as the most effective amendment against drought stress in distinct agroecological zones, different soil types, and contrasting wheat cultivars worldwide.

No abstract

No abstract

Drought stress is among the major constraints that threat agricultural productivity within the arid and semi-arid regions, worldwide. In this study, wheat (a strategic crop) was selected to test its growth under drought stress and the mechanisms beyond this adaptation while considering two factors, i.e., (1) deficit irrigation at 35% of the water holding capacity (WHC) versus 75% of WHC (Factor A) and (2) the following safe treatments: the control treatment (C), amending soil with biochar (BC) at a rate of 2%, foliar application of 24-epibrassinolide at two different levels (1 (BR1) or 3 (BR2) µmol) and the combination between BC and BR treatments. The obtained results were statistically analyzed, and the heat-map conceits between measured variables were also calculated by using the Python software. This investigation took place under the greenhouse conditions for 35 days following a complete randomized design and all treatments were replicated trice. Results obtained herein revealed that drought stress decreased all studied vegetative growth parameters (root and shoot biomasses) and photosynthetic pigments (chlorophyll a, b and total contents while increased oxidative stress indicators. All additives, specifically the combined ones BR1 + BC and BR2 + BC, were effective in increasing growth attributes, photosynthetic pigments and ion assimilation by wheat plants. They also upraised the levels of enzymatic and non-enzymatic antioxidants while decreased stress indicators. Furthermore, they increased Ca, P and K content within plants. It can therefore be deduced that the integral application of BR and BC is essential to mitigate drought stress in plants.

Drought stress is among the major threats that affect negatively crop productivity in arid and semi-arid regions. Probably, application of some additives such as biochar and/or brassinosteroids could mitigate this stress; however, the mechanism beyond the interaction of these two applications is not well inspected. Accordingly, a greenhouse experiment was conducted on wheat (a strategic crop) grown under deficit irrigation levels (factor A) i.e., 35% of the water holding capacity (WHC) versus 75% of WHC for 35 days while considering the following additives, i.e., (1) biochar [BC, factor B, 0, 2%] and (2) the foliar application of 24-epibrassinolide [BR, factor C, 0 (control treatment, C), 1 (BR1) or 3 (BR2) μmol)]. All treatments were replicated trice and the obtained results were statistically analyzed via the analyses of variance. Also, heat-map conceits between measured variables were calculated using the Python software. Key results indicate that drought stress led to significant reductions in all studied vegetative growth parameters (root and shoot biomasses) and photosynthetic pigments (chlorophyll a, b and total contents) while raised the levels of oxidative stress indicators. However, with the application of BC and/or BR, significance increases occurred in the growth attributes of wheat plants, its photosynthetic pigments, especially the combined additions. They also upraised the levels of enzymatic and non-enzymatic antioxidants while decreased stress indicators. Furthermore, they increased calcium (Ca), phosphorus (P) and potassium (K) content within plants. It can therefore be deduced that the integral application of BR and BC is essential to mitigate drought stress in plants.

No abstract