To study the effect of salinity stress on some physiological traits in wheat cultivars (Triticum aestivum L.), a factorial experiment based on randomized complete block design with three replicates was performed at 2017 in the research greenhouse of Agronomy Department, University of Tehran. Salinity treatments at two levels; control (1.2 dS/m) and sodium chloride treatment (16 dS/m) and seven wheat cultivars, Rowshan, Inia-66, Mahdavi, Khazar-1, Karaj-2, Ghods and Shole were the experimental treatments. According to the results, relative water content, yield and its components and potassium/sodium ratio decreased in all genotypes while Na+ content and remobilization of carbohydrates were increased. Salt resistant varieties, Roshan and Inia-66, had the highest level of relative water content, remobilization of soluble carbohydrates and number of grains per spike. In addition, Roshan cultivar showed the highest potassium concentration and K+/Na+ in the shoots, while Ghods and Sholeh as sensitive cultivars had the highest sodium concentration in the shoots. Findings showed that the ability of a cultivar to remobilize soluble carbohydrates is one of the traits that determine salt stress tolerance, hence, this trait is suitable for evaluating salt tolerance of wheat cultivars in the future investigations.

In order to study the effect of deficit irrigation on RWC, proline concentration, antioxidant enzymes content, chlorophyll concentration and forage yield of five clover species, a field experiment was conducted during the cropping season 2019-2020.  The experimental design was split plots arranged based on randomized complete blocks design (RCBD) with three replications. Deficit irrigation  at three levels (0 (Full irrigation), 20 and 40% less than the irrigation requirement) were considered as main plots and  five clover species (Trifolium resupinatum ، T. alexandrium ، T. lapaceaum ، T. echinatum و T. diffusum) were allocated as sub plots.The results showed by increasing deficit irrigation up to 40%, proline concentration increased by 93% and the content of antioxidant enzymes catalase, peroxidase and superoxide dismutase increased by 12, 98 and 83% respectively. However, RWC, yield of fresh and dry fodder decreased by 22, 24 and 29% respectively. The highest RWC, chlorophyll concentration and content of antioxidant enzymes were observed without significant difference in T. resupinatum and T. alexandrium species. The interaction effect of two factors (deficit irrigation × species) showed by increasing deficit irrigation, fresh and dry forage yield of all five species decreased significantly. In all three levels of deficit irrigation, the highest yield of fresh (20.39, 18.81 and 13.94 t/h) and dry forage (4.59, 4.25 and 3.06 t/h) were obtained in T. resupinatum species. In general, the results showed that all 5 species do not have the required stability under stress conditions. Therefore, deficit irrigation for the proposed species will be justified only if a 20 and 40 percent irrigation water reduction is more beneficial than the yield reduction.

Effective screening techniques for drought resistance would be beneficial in wheat (Triticum aestivum L.) breeding programs. Two drought resistance criteria. consisting of relative water content (RWC) and stomatal resistance were evaluated in field and greenhouse to investigate drought resistance in five wheat cultivars reputed to differ in drought resistance: Alvand and B. C. Roshan (resistance), Zarrin and C-73-5 (moderate and Navid (susceptible). In both experiments, R WC decreased with progressing in phonological stages. There was a significant difference in RWC among cultivars (except at stem elongation stage in the field) but drought resistant genotypes has not superiority to susceptible ones. In greenhouse a significant linear relationship was obtained between RWC and yield reduction ratio as determined by Yr=1-(Ys/Yp)(Ys and Yp=yield under stress and non-stess conditions, respectively). In stress conditions, stomatal resistance in the greenhouse was higher than in the field. Stomatal resistance and yield reduction ratio in greenhouse showed a significant correlation. It seems that there is a relationship between RWC and stomatal resistance and these criteria were recognized as beneficial drought resistance indicator but the time of drought stress is an important factor in this subject.

The aim of this study was to assess the crop water stress index (CWSI), derived from leaf temperature using infrared thermometer measurements, to investigate the water stress status and irrigation timing of olive trees. Fpr this purpose a regression function was determined between crop water stress index and relative water content of leaf (RWC) and soil water content (SWC). The experimental treatments involved two olive cultivars (Koroneiki and T2) and four water regimes (irrigation of 100, 85, 70 and 55% of crop water requirement). The results showed that the non-water stressed baseline is varied throughout the study period as well as during the day. The daily variations of non-water stressed baseline were mainly due to variations in the intercept of the non-water stressed baseline that can be explained by variations in zenith solar angle. After investigating the relationship between vapor pressure deficit (VPD) and the difference between crop and air temperature (𝑇 𝑐 − 𝑇 𝑎 ), the equation of Tc-Ta =-0. 45 VPD+1. 06, r2 = 0. 99 was determined for the non-water stressed baseline of the olive trees at 12: 30 pm. Crop water stress index of olive trees increased significantly in deficit irrigation regims compared with control trees. crop water stress index was significantly correlated with relative water content (Kroneiki: r2=0. 82**, T2: r2=0. 80**) and soil water content (Kroneiki: r2=0. 66**, 𝑇 2: r2=0. 69**). Therefore, the crop water stress index is a good indicator of the water stress status of the Koroneiki and T2 olive trees.

Harvest time, in olive, is an important key to achieve high quality and quantity of oil with a desired and balanced fatty acid (high oleic acid and low palmitic and linoleic acid) composition. Appropriate harvesting time varies in different locations depending on climatic and agronomic situations and identifying the right time for harvesting may bring about a high quality oil. Thus, the current study was carried out to determine the best harvesting time for two Iranian (Mari and Shenge) and two foreign (Kroniki and Arbequina) cultivars in the region of Tarom, Zanjan, (north of Iran). The results obtained indicated that palmitic, oleic and stearic acid contents decreased and linoleic and palmitic acid contents increased with the progress of ripening. In addition, oil percentage increased with the progress of fruit growth and development. Based on the amount of desired fatty acids, the best harvesting time for the Mari, Kroniki and Arbeqina cultivars, was 180 days after full bloom. It was revealed that the cultivar Shenge is not suitable for oil extraction, due to the low percentage of oleic acids. Therefore, Shenge could be cultivated for producing olive cans rather than olive oil and the best harvesting time for Shenge is 120 days after full bloom.

In order to evaluatethe effect of salicylic acid on some morpho physiological charactristics of Calendula officinalis. L. under water deficit stress, an experiment was set out in split plot design based on RCBD with three replications under Zanjan climate conditions. Treatments consisted of 3 different irrigation regimes (100, 66, 33% ETC) as main plot and SA at 4 levels (0, 0. 5, 1, 1. 5 mM) as sub plots. Results indicated that, water deficit stress significantly increased proline content and peroxidase enzyme activity and reduced height, fresh and dry weights of shoot, flower number, flower vase life and leaf relative water content (RWC). Foliar application of SA at the 1 mM significantly increased fresh and dry weight of shoot, flower number, flower vase life, relative water content (RWC), peroxidase enzyme activity and proline content under water deficit stress. According to the results of this research, foliar application of salicylic acid could improve plant response in most traits at 1% level to drought stress.

In order to investigate the effect of different levels of water deficit and foliar application of humic acid on the physiological characteristics of lima bean, a field experiment was arranged as split-split plot based on randomized complete block design with three replications in the research station of Shahrekord University in 2014. The main plot included four levels of drought stress (50, 70, 90 and 110 mm evaporation from pan class A) and sub plots included four levels of humic acid (0, 1, 3 and 6 lit/ha). In this experiment the traits of Chlorophyll a, chlorophyll b, carotenoids, membrane stability, relative water content of leaves, proline and soluble sugars were evaluated. The results showed that water stress caused significant decrease in all measure traits. Humic acid also significantly increased them. The interaction of water stress and application of humic acid on the carotenoids and proline were significantly affected, but had no effects on other traits. Foliar application of humic acid under drought stress conditions increased concentration of osmo-regulation including soluble sugars and proline and thus maintain osmotic pressure in cells, resulted the plant to resistant in drought conditions.