k. maghsoudi

With the aim of evaluating the effects of salicylic acid and brassinosteroid application on some physiological traits and arsenic accumulation in spinach under arsenic stress conditions, an experiment was conducted in a factorial experiment in the form of a randomized complete block design with four replications in the year 2022 in the Nutrition Research Center, Department of Food Hygiene and Quality Control, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Iran. The experimental factors included salicylic acid (0, 0.5, and 0.75 mM), brassinosteroid (0, 0.5, and 0.75 µM), and arsenic stress (0, 50, and 100 µM). Arsenic stress, especially at 100 µM, reduced the net photosynthetic rate, transpiration rate, stomatal conductance of spinach leaves and biomass. Arsenic stress increased the concentration of malondialdehyde, hydrogen peroxide, osmolytes, as well as antioxidant enzymes activities in spinach plants. Application of brassinosteroid and salicylic acid significantly increased activities of antioxidant enzymes (peroxidase, ascorbate peroxidase, and superoxide dismutase), osmolytes accumulation (carbohydrates and proline) and spinach biomass; in contrast, application of brassinosteroid and salicylic acid decreased the concentration of malondialdehyde and hydrogen peroxide in spinach plants under arsenic stress conditions. Arsenic accumulation was higher in spinach roots than in leaves. Under 100 µM arsenic stress, the application of different concentrations of salicylic acid and brassinosteroid, individually and in combination, significantly reduced arsenic accumulation in spinach, with the highest positive effect being observed in the treatment of 0.75 mM salicylic acid + 0.75 µM brassinosteroid. In conclusion, brassinosteroid and salicylic acid application increased the tolerance of spinach plants against arsenic stress by improving gas exchange, activity of antioxidant enzymes, accumulation of osmolytes, stability of the membranes, and as a result plant biomass; the positive effects of brassinosteroid and salicylic acid together were greater than that of brassinosteroid or salicylic acid applied separately.

Ascorbic acid and melatonin as the biostimulants affect the biosynthesis of phytohormones, facilitate and increase the nutrients uptake, enhance the defense mechanisms, stimulate the root growth, and finally, increase the quality and quantity of the product by affecting the plant metabolites. This study was conducted in a randomized complete block design with three replications to investigate the effects of foliar application of melatonin and ascorbic acid on the grain yield and mucilage content of Plantago ovata Forssk. in the research greenhouse of Bardsir Faculty of Agriculture, Shahid Bahonar University of Kerman in 2020. The experimental treatments included the foliar application of distilled water (control), melatonin 100 μM, ascorbic acid 100 μM, and melatonin 100 μM + ascorbic acid 100 μM. The foliar application treatments continued from the time of complete establishment of seedlings (3-4 leaves) to the physiological maturity stage of seeds (four times every two weeks). The results showed that the foliar application of melatonin and ascorbic acid (single and combined application) enhanced the number of tillers per plant, number of spikes per plant, spike length, number of seeds per spike, and 1000-seed weight significantly. The highest grain yield was obtained from the foliar application of melatonin (59.98 g.m-2) and melatonin + ascorbic acid (61.85 g.m-2) without statistically significant differences with each other. The ascorbic acid foliar application also significantly increased the grain yield by 6.61% compared to the control. The foliar application of ascorbic acid, melatonin, and melatonin + ascorbic acid increased the mucilage content by 12.29, 19.89, and 23.80%, respectively compared to the control. The application of melatonin alone or in combination with the ascorbic acid, without statistically significant differences with each other, had the greatest positive effect on increasing the mucilage percentage. The mucilage yield was obtained 10.03, 13.47, 14.94, and 15.64 g.m-2 in the control, ascorbic acid, melatonin, and melatonin + ascorbic acid treatments, respectively. Based on the results, it can be concluded that the foliar application of melatonin and ascorbic acid could improve the quantitative and qualitative yield of P. ovata, and among the treatments their combined application was more effective.

In order to evaluate morpho-physiological responses of hybrid corn KSC750 to water stress at various stages of growth, a field experiment was conducted at the Pasargad region (northwest Fars) in 2010. The experiment carried out as a randomized complete block design, with 3 replications. In this study, corn growth period was divided into three phases: the establishment of plant to tasseling (phase I), tasseling to dough development (phase II) and dough development to ripening (phase III). Treatments were consisted of control, irrigation cut off after dough development, water stress of 75 percent of FC during vegetative phase and after dough development, water stress of 75 percent of FC during whole growth phase, water stress of 50 percent of FC during vegetative stage and after dough development and water stress of 50 percent of FC during whole growth phase. Results showed that mild drought stress (75% FC) at vegetative phase was not significantly effected growth and yield of corn. However, application of drought stress during the whole growth period significantly reduced morphological parameters as well as yield and yield components. Based on these results, flowering and grain filling stages were identified as more sensitive stages to drought stress in corn. Moreover, irrigation cut off after dough development terminated to a satisfactory yield. The results indicated that, overall, under Pasargad region and similar agro climatic conditions, it would be possible to save water to 75 percentage of corn water requirement through application of deficit irrigation after dough development stage.

Drought stress, as one of the most important environmental stress, plays a vitalrole in reducing crop yield all around the world. Super absorbent hydro gels which absorbs high amount of water are known as compounds which can reduce detrimental impacts of drought stress. In order to investigate the effects of super absorbent hydro gels on soil condition, an experiment was conducted at the institute of higher agricultural education of natural rources, Jiroft City. Three replications were used in the experiment. Drought stress condition was applied to the main plots at three levels, irrigation of 100% of crops water requirement (no stress), 75% (mild stress) and 50% (severe stress) and super absorbent levels were applied to the sup-plots at three levels (0, 200 and 300 kg/ha). Drought stress reduced grain yield, yield components and biological yield. Yield reduction was higher at 50% crop water requirement. On the contrary, super absorbent hydro gels particularly at 300 kg/ha diminished the detrimental effects of water stress on yield. Application of super absorbents caused higher number of rows per ear only under drought stress condition. Meanwhile, grain yield, biological yield, grain weight and number of grains per row were under both stress and non-stress conditions. It was concluded that application of super absorbent hydro gels can increase yield and yield components through increasing soil water holding capability for a long time.