Evaluation of the physiological and biochemical traits can help to identify strategies for selection of resistant cultivars and increased crop yield production under diverse environmental conditions such as drought stress conditions. To this end, an experiment was laid out in a split–plot arranged as a randomized complete blocks design with nine cultivars, two levels of water regimes and three replications during 2010-2011 seasons at the Research Farm of Razi University of Kermanshah. The results showed that post-anthesis water deficit significantly decreased grain yield, biomass and grain weight and had not significant effect on other yield components. In well watered and water deficiency stress, Sivand and DN-11 had the greatest grain yield, respectively. Chamran cultivar showed the lowest grain yield under post-anthesis water deficiency stress. Post-anthesis water deficiency stress significantly decreased leaf soluble proteins concentration, chlorophyll a, b and a/b ratio and greenness index. Despite the reduction of photochemical efficiency of photosystem II, relative water content and stem’s soluble sugar concentration under post-anthesis water deficiency stress, these reductions were not significant.

To investigate the effect of Wokozim Fertilizer, containing seaweed, on potato hybrids obtained from the crossing of Savalan and Satina cultivars under normal and water deficiency stress conditions was conducted in the laboratory of Zare Gostar Arta Technology Company, under in vitro conditions, during 2017. The experiment was performed as a factorial experiment in a completely randomized design with three replications. The first factor consisted of three levels of polyethylene glycol 6000 (zero, -3 and -6 bar) to apply water deficiency stress and the second factor consisted of three levels of Wokozim (zero, 30 and 60 ml /L). The effect of water deficiency stress on all traits and the effect of Wokozim on the all studied traits except for seed germination percentage was significant. The interaction effect of water deficiency × Wokozim was significant for all traits except stem length. Stem length decreased due to increasing water stress intensity. The maximum stem length (4.67 cm) was observed at the 30 ml/l of level of Wokozim fertilizer. The water deficiency stress reduced the values of all traits. According to the results, in conditions of severe stress, application of 60 ml/l of Wokozim can improve germination percentage, root and stem length, but had no significant effect on weight and number of microtubers. In addition, in conditions without stress, 60 ml /l and Wokozim can improve most of the traits.

Among different cereal crops, wheat has the most cultivation areas and yield in the world. Also, wheat is the major crops grown in arid and semi-arid regions. The occurrence of drought stress during grain filling is the prominent and inevitable characteristic of these areas. The objectives of this research were to determine the effect of water deficiency and the role of current and storage sources of assimilates on grain filling, grain yield and carbohydrates remobilization. Therefore, an experiment was carried out in a split-plot factorial arranged in a randomized complete block design with three replications during 2010-2011 cropping season at the Research Farm of Razi University in Iran. The main factor was the irrigation treatments including control or non-stressed treatment (irrigating plants at all growing stages based on crop water requirement and climatic conditions) and water deficit stress (irrigation cessation after anthesis). The combination of eight wheat cultivars including Bahar, Parsi, Pishtaz, Pishgam, Chamran, Zarin, Sivand, Marvdasht and one line DN-11 along with the photosynthetic sources limiting treatments including control (no limitation of photosynthetic sources), defoliation of the flag leaf, defoliation of all leaves except the flag leaf), de-awning and shading over the ear were considered as the sub plots. The results showed that post-anthesis water deficiency significantly decreased grain yield (22.2%) and removal of photosynthetic sources reduced grain yield through reducing the grain weight. In this case the role of spike photosynthesis in grain filling (35.4%) was greater than the flag leaf and lower leaves roles (18.6 and 18.5%, respectively) and awns had the lowest role in grain filling (3.3%). Under removing of assimilate sources, remobilization of stored material from the different parts of stem internodes was increased, suggesting the compensatory role of them in yield loss prevention. Water deficit stress could not increase the remobilization efficiency, but in terms of mentioned traits, there were differences amongst cultivars and different removing photosynthetic sources. In both control and water deficiency stresses treatments, the amounts of remobilization from different parts of stem and spike to the growing grains were similar. Under well water condition, the grain yield increased due to higher photosynthesis rate compared to water deficiency stress conditions.

Occurrence of drought stress at grain filling period is the prominent and inevitable characteristic of arid and semi-arid regions. The objectives of this research were to determine the effect of water deficiency and the role of current photosynthesis on grain filling, photosynthesis and gas exchange. Therefore, an experiment was carried out in a split-plot design based on a randomized complete block design with three replications at the Research Farm of Razi University in Iran during 2010-2011 cropping season. The irrigation treatments including non water stress (full irrigation over the whole season) and water deficiency stress (irrigation cessation after anthesis stage) were considered as main plots, while the factorial combination of eight wheat cultivars including Bahar, Parsi, Pishtaz, Pishgam, Chamran, Zarin, Sivand, Marvdasht and DN-11 line and the source manipulation treatments including control (Non source limitation), defoliation of flag leaf, defoliation of all leaves except the flag leaf, removing awns and shading over ears, were considered as sub-plots. The results showed that, post-anthesis water deficiency significantly decreased grain yield (22.2%) and 1000-seed weight (18.6%) compared to the control treatment and Removal of photosynthetic sources of assimilates reduced grain yield owing to grain weight reduction. The contribution of spike photosynthesis to grain filling (35.4%) was greater than the flag leaf (18.6%) and lower leaves (18.5%) and also, awns had the lowest contribution to grain filling (3.3%). Grain filling period was shortened during water deficiency stress, so that it reduced from 35 days under control conditions to 28 days under stress conditions, whereas it caused an increase in seed filling rate. Moreover, results indicated that photosynthetic source limitations caused an increase in photosynthetic rate and gas exchange. This increase reflects the compensatory role of photosynthetic rate of remained leaves in preventing yield loss.

In order to investigate the effect of silicon concentration in substrtae on some physiological, biochemical and growth characteristics of wheat (Triticum aestivum L. cv. Chamran) under available-water deficiency, this experiment was conducted in Ramin Agricultural and Natural Resources University, Khuzestan, Iran, in 2012. The experiment was arranged as factorial, based on randomized complete blocks design with three replications. Treatments included available-water deficiency stress at three levels (non-stress (control), mild stress (-5 atm osmotic pressure) and severe stress (-10 atm osmotic pressure) by solving 175 and 230 grams of polyethylene glycol 6000 per liter of distilled water). The second factor was different levels of silicon (0, 1, 2 and 3 mM/L) in the form of potassium silicate (K2SiO3). Results showed that the effect of water-deficiency stress increased significantly the proline content (74.4%) and silicon concentration of shoots (69.1%) and reduced the soluble proteins content, stomatal conductance, membrane stability index and shoot and root dry weight by 18.6, 66.6, 24.2 37.8 and 51.9%, respectively, as compared to control treatment. Also, the effect of silicon concentration in the nutrients solution, except root dry weight, was significant on the other traits. Silicon had the greatest impact on shoots’ silicon content and led to a 53% increase in this index. The presence of silicon in non-stress treatment had no significant effect on the traits and its effect was enhanced with an increase in stress intensity. Application of 2 and 3 mM/L of silicon increased shoot dry weight by 18 and 21% in mild stress and by 25 and 31% in severe stress conditions, respectively, as compared to no-silicon treatment, and there was no significant difference between these two values

More plains of Iran are located in arid and semi-arid regions and so agricultural production systems depend heavily on water. Recently, the reduction of water resources has become a serious threat for crop production such as cotton planting. Therefore, application of low irrigation methods can be an appropriate method to cope with mentioned condition. In addition, it is vital to identify the cotton cultivars reaction to water deficiency. Sensibility of some cotton cultivars is lower than others. Sensitive cultivars seed cotton yield decreases more than tolerant cotton cultivars. Moreover, some of growth stages in cotton plant are more sensitive to water deficiency stress. For example, flowering stage is more sensitive than vegetative growth stage, and boll number per plant is more effective parameter on yield than boll weight. Ulla and et al (2) showed that there are genetic variations for drought stress toleration in cotton plant. Afshar and Mehrabadi (3) indicated that low irrigation on the basis of 50% and 75% of cotton water requirement had no significant effect on vegetative growth of cotton plant. However, it caused the increase of flower and boll shedding per plant. Application of tolerant cultivars compared with sensitive cultivars can increase seed cotton yield under drought stress condition. Consequently, the aim of this study is to survey yield and related morphological traits reactions in sensitive and tolerant cotton cultivars to different water deficiency levels.
Two tolerant cotton cultivars (Armagan and Varamin) and two sensitive cotton cultivars (Coker349 and Nazili84) as a subplot at three irrigation levels (as a main plot) using split plot design based on complete block design with three replications were carried out at Agricultural Research Station of Kashmar in 2011. Three levels of water consumption based on Penman-Montith method and using cotton KC coefficients were [33% (I33%), 66% (I66%) and 100% (I100% of water requirement)] that it were take placed using drip irrigation method. Yield and yield components traits such as height, the number of boll per plant, boll weight, flower and boll shedding percent, seed cotton yield, biological yield, earliness percent and harvest index were determined at the end of experiment. Data analysis was carried out using Excel and MSTAT-C software.
The results showed that although water deficiency stress decreased vegetative components, the amounts of decreasing were higher in tolerant cultivars than sensitive cultivars but, by contrast, the reproductive components of tolerant cultivars indicated lower decreasing than sensitive cultivars under water deficiency stress. For example, Varamin cotton cultivar had more number of bolls per plant than Coker349 as a sensitive cultivar. The results also showed that more retention of boll number per plant was the main factor of cultivars difference as for seed cotton yield. The highest number of boll and flower per plant retention belonged to sensitive cultivars such as Coker349 and Nazili (71.2 and 69 percent, respectively) at 66 percent of water consumption and the lowest number of boll and flower per plant retention were 92.3 percent belonging to Varamin as a tolerant cotton cultivar at full water irrigation treatment. The results indicated that all yield components except boll weight were significantly affected by low irrigation levels. In addition, the results revealed that low shedding of flower and boll and accordingly more retention of boll number per plant and also biomass preservation under drought stress were the main factor in yield of tolerant cultivars in comparison with sensitive cultivars. Biological yield reduction was higher than seed cotton yield under water stress condition. High and significant correlation was observed among yields with boll number per plant, biological yield and harvest index under drought stress. Moreover, there was a significant correlation between yield with plant height and biological yield only in full irrigated treatment. Furthermore, harvest index decreased significantly under drought stress. Harvest index value for Coker349 was significantly lower than other cultivars. Coefficient correlation between harvest index and yield and its components showed that harvest index was more dependent with seed cotton yield to biological yield. Therefore, tolerant cultivars had higher seed cotton yield and also biological yield in comparison with sensitive cultivars. While there was a significant correlation between yield with plant height and biological yield only in full irrigated treatment.

This research was conducted to study the effects of water deficiency stress, nitrogen application rates, and plant population on Water Use Efficiency and Nitrogen of oily sunflower in 2007-2008 Agriculture and Research center of West-Azerbaijan. The study was consisted split-split-plot experiments using Randomized Complete Block Design with 3 replications. The factor main was consisted irrigation treatment including optimum irrigation, moderate stress and sever stress where irrigation was done after depletion of 50%, 70% and 90% of field capacity, respectively. Three nitrogen levels consisting of 100, 160 and 220 Kg N ha-1 were considered as sub plots and sub-sub plots consisted of three plant population of 5.55, 6.66 and 8.33 plant m-2.The results indicated that water deficiency stress, nitrogen and plant population on grain and biological yields, seeds per head, head diameter, kernel percentage to seed, 1000 grain weight, plant grain yield and harvest index were significant. The maximum grain yield (4200 kg/ha) was related to optimum irrigation treatment. Severe drought stress reduced the grain yield by 44% compared to the optimum irrigation condition. Grain yield increased with nitrogen application rate. The response of grain yield to increase in plant population was positive. All yield components were responded to the changes in plant population. The harvest index decreased with increasing severe drought stress and plant population. According to this research derived results application of 220 kg N ha-1 and plant population increase in optimum conditions and moderate drought stress is recommended for suitable yield, although nitrogen consumption and plant population increase has a little impact on grain yield in severe drought stress conditions.

To evaluate the response of hulless barley promising lines to water deficiency stress, 15 genotypes were assessed under three irrigation regimes (complete irrigation and water stress at booting and grain filling stages) at field and greenhouse conditions using split-plot design arranged in randomized complete blocks with three replications. The result of analyses revealed significant differences among the genotypes for all of the studied characters. Based on the combined data mean comparison, genotypes 1, 2, 3, 5, 6, 11 and 12 showed the highest yield. However, among these genotypes, the minimum yield reduction under the stress conditions compared with the normal irrigation was observed in lines 3 and 10. Therefore, these lines can be used as promising genotypes in breeding program for improvement of drought tolerance and as parental lines for mapping of genes involved in drought tolerance. Genotype ranking based on the characters evaluated at the field and greenhouse revealed the highest ranks for genotypes 1, 3 and 5. The result indicated that these lines have other desirable characters such as harvest index, biomass and tiller beside high yield.

Plant growth regulators are the main factors in grain yield formation However, their physiological roles have not been fully identified. On the other hand, water stress is the main factor in reducing grain yield and germination characteristics. To this end, two experiments were carried out in the research farm and laboratory of Campus of Agriculture and Natural Resources of Razi University in Iran during 2010-2011 and 2011-2012 years in a split-plot factorial arranged in a randomized complete blocks design with three replications. The irrigation treatments including non water stress and water deficiency stress (from anthesis and continued until physiological maturity). The wheat cultivars including Pishtaz, Marvdasht, DN-11and 336 and the foliar application of indole acetic acid (dose of 50 μM)treatments including control, used at the beginning of grain growth (from anthesis) and at the beginning of grain filling (from 14 days after anthesis) at the entire plants. Under non water stress, the grain yield of Marvdasht was greater than other cultivars. More yield reduction of this Marvdasht in water deficiency compared to other cultivars showed more sensitivity of this cultivar to post-anthesis water deficiency and DN-11 in this situation had the lowest grain yield reduction. Foliar application of indole acetic acid (IAA) at the beginning of grain growth caused the most increase in grain yield. In this situation, IAA caused more increase in the grain yield of Marvdasht cultivar. But, this treatment at the beginning of grain filling did not have such effect. Seeds were obtained from the field were studied in the view of germination and seedling growth characteristics in the laboratory and the result showed that, plumule length and germination percentage were not affected by post-anthesis water deficiency. Under post-anthesis water deficiency, Plumule to radicle ratio and germination rate significantly increased and other parameters showed a significant decrease. Mean comparison of foliar application of IAA at the beginning of grain filling showed that this significantly increased germination characteristics. With respect to these results, Auxin may via positive effects on seed quality and not quantity (seed weight) may be had positive effects on seed germination characteristics.

IntroductionMajor cultivated cotton regions of Iran are located in dry and semiarid climates, therefore water deficiency or drought stress is inseparable part of cotton production systems in these regions. So identification and introduction of drought tolerant cotton genotypes is crucial. showed that water stress decreased plant growth rate, leaf area and finally photosynthesis in cotton. In addition plant height reduction is a primary effect of water stress. According to results, net photosynthesis, stomatal conductance and transpiration decreased simultaneously with an increase in drought stress intensity.
Physiologic traits monitoring were notified as a proper gadget for selection and improvement of germplasm. Whereas investigation of many genotypes in field conditions under drought stress is difficult and it is not accurate enough, also good correlation has observed between the results of drought tolerance at seedling stage and field experiments, therefore this research has tried to evaluate some of the morphologic traits in cotton genotypes at seedling stage under drought stress and none stress conditions.
Materials and Methods22 cotton cultivars were grown under none water stress (field capacity) and drought stress conditions(-1MPa) using a factorial arrangement of treatments based on randomized completely design with three replications at College of Agriculture, Ferdowsi University of Mashhad in 2011. Then each genotype (10 seed) was sown at a pot (1.5 l-1). At two true leaf stages, pots were tinned to one seedling. Soil moisture content was kept up to two true leaf stages at field capacity and at the end of experiment, it was conserved about -1MPa using weight method.
The measured parameters were:Plant height, leaf area, dry weight of leaf, stem, root and whole plant and also decreasing percent of each parameter under stress in comparison with control in any genotype was determined at the end of experiment. Stomatal resistance and leaf temperature were measured with leaf porometer set (model Decagon Devices, Inc) on three leaf stage of cotton seedling. Relative water content (RWC) of leaf was also measured. Variance analysis, Comparison of trait means and correlation between traits were carried out using SAS and Excel and least significant difference (LSD).
Results and DiscussionInteraction between water deficiency stress and cotton cultivars were significant (P