s. ali mohammad modarres-sanavy

One of the most important problems threatening agriculture is water deficit stress in many regions of the world. Water deficit stress could result in a decrease in yielding or death of a wide range of crops. In Iran, like other arid and semi-arid regions, forage quality and production have decreased due to the occurrence of frequent water stress. Restriction of water resources, especially in arid and semi-arid regions where agricultural systems depend on supplementary irrigation, has become the most important problem of fodder production. Persian clover (Trifolium resupinatum L.) is a forage legume cultivated in the temperate region of world; it is of great value for livestock feed, soil improvement, and reclaiming disturbed land because of its nitrogen-fixing capability. The purpose of this research, was evaluate the effect of water deficit stress on the physiological and qualitative traits of fodder of Persian clover.

An experiment was carried out during the 2016 and 2017 cropping seasons as a randomized complete block design at the Research Farm of Tarbiat Modares University. Experimental treatments included water deficit stress at four levels. The tested treatments included water deficit stress at four levels (irrigation after reaching the levels of 80, 60, 40 and 20% available moisture). Irrigation of all treatments was carried out at the level of 70% of available water until the start of stress in the final stages of vegetative growth of the second cut. To measure the effects of water deficit stress on physiological traits physiological indexes were recorded during the first 10 days of stress treatment, every day. The clovers were harvested at about 20-25% flowering stage. After drying, they were transferred to the laboratory to determine the quantitative and qualitative feed yield. Based on Bartlett's test results, the experiment's dependent variables had the same trend.

The results show that the irrigation regime had a significant effect on all traits. Irrigation treatments at 80 and 60% of available water had the highest dry matter yield, and delaying irrigation until 40 and 20% caused a 19% and 36% significant decrease in this trait. Also, stress at the level of 20% caused a 27% decrease in fodder protein, a 10% increase in acid detergent fiber and neutral detergent fiber, and finally, an 16% reducing relative feed value. Evaluation of physiological traits in the first ten days of the beginning of water stress showed a continuous increase in leaf temperature from 30.5 to 34 ˚C, and 49, 50, and 15% decrease in photosynthesis rate, stomatal conductance, and SPAD index, respectively. It Also reduces the concentration of chlorophyll a and b 25 and 40 percent. The return of increased leaf temperature and reduced stomatal conductance due to the discharge of 80% moisture was fast to the initial level, but other traits slowly approached the value before the stress. It seems that returning to initial values at levels of 80 and 60 is easily possible for the plant, but with the increase in the intensity of stress, the damage of dehydration is slowly compensated.

The experiment results showed that the photosynthesis rate and other physiological traits of Persian clover significantly react to the soil's decreased available water. In most physiological traits, irrigation after the available soil moisture reached 60% caused a relatively quick return to the initial value. There was no significant difference in fodder yield in the 80% and 60% irrigation treatments. When the available soil moisture reached 40%, the physiological traits showed a greater decrease than before. It seems that some damages to physiological traits are irreparable to such an extent that they eventually lead to a drop in yield or a decrease in the quality of Persian clover fodder. Finally, it is not necessary for clover irrigation at levels of more than 60% of available water, taking into account the more quality of forage in the level of 60% (about 1.5% of insoluble fiber, and 11% feed value), considering the water conditions of the country.

The chickpea is mainly cultivated in agricultural systems in arid and semi-arid regions and needs low input. Specifications such as the ability to fix nitrogen, deep rooting and the effective use of atmospheric depression have led the plant to play an important role in stabilizing crop production systems. On average chickpea seed contain 23% protein is highly digestible. Water deficit stress is the most important factor limiting the growth and agricultural products in arid and semi-arid regions of the world. Drought stress is one of the most important factors in grain yield reduction of chickpea during pod formation and grain filling. Amino acids facilitate the transfer of food in the vascular system by improving the permeability of the cell membrane. In plants under drought stress or salinity, proline is widely used as an osmotic regulator. In fact, amino acids are the main chain in the protein structure, and in turn, are effective in plant growth. Increased proline in chickpea leaves is a mechanism for osmotic adjustment under water stress conditions. Using the priming method is one of the methods for improving seed function and increasing the quality of seeds in adverse environmental conditions, In fact, priming shortens the time from planting to emergence and protects seed of harmful biotic and abiotic factors in the critical stage of seedling establishment. These treatments also result in the emergence of uniformity, resulting in a uniform establishment and improved yield in the crop.

In order to study the effect of Anti-stress materials priming and foliar application on quantitative and qualitative yield of chickpea (Cicer arietinum) Adel cultivar under Irrigation regime an experiment was conducted at the Research Farm of Agriculture of Tarbiat Modares University as randomized complete block design arrangement in split plot with three replications. The main plots were included 1- optimal irrigation 2- Moderate Irrigation 3- severe Irrigation as withholding irrigation until depletion of 20, 45 and 70 percent of soil available water at root development zone respectively and then the plots were irrigated to field capacity from flowering to plant harvest. Priming and foliar application of anti-stress materials including proline, valine, alanine, commercial combination of amino acids and distilled water together with without anti-stress materials were randomized to the subplot units.

The results showed that priming and foliar application of anti-stress materials and optimal irrigation incresed the number of primary branches to the 58.31% and 36.38%, plant fresh weight to the 108.25% and 36.16%, chlorophyll a to the 40.90% and 68.35%, number of seeds/plant to the 74.48% and 34.66%, pod per plant to the 48.13% and 45.12%, duration of ripening to the 9.53% and 8.65, yield forage to the 30.56% and 39.44%, biological yield to the 65.16% and 44.82% in chekpea in compring with using severe irrigation and without priming and anti-stress materials foliar application treatments repectively. Also 1000 kernel weight and harvest index were increased %20.67 and 27.82% in optimal irrigation related to severe irrigation. Interaction effects between irrigation regimes and anti-stress materials on chlorophyll b showed that the highest rate chlorophyll b related to optimal irrigation with using commercial amino acids to to the 80% and the least it related to severe irrigation without anti-stress materials to the 24%. Application of amino acids was significant in most traits such as number of primary branches, plant fresh weight, chlorophyll a, chlorophyll b, Number of seeds/plant, pod per plant, duration of ripening, yield forage, biological yield.

Drought stress reduced photosynthesis and limited the amount of assimilate and thus reduced the yield and yield components In this experiment. In most cases, the application of priming and foliar application of amino acids had a positive effect on the traits, including number of primary branches, plant fresh weight, chlorophyll a, chlorophyll b, number of seeds/plant, pod per plant, duration of ripening, yield forage, biological yield at drought stress condition. Therefore, the use of amino acids, especially its commercial combination or proline, is recommended to reduce the effects of water deficit stress in the chickpea Adel cultivar.

Drought is a common problem that seriously affects the quantity and quality of agricultural produce. More than 50% of the world's regions are located in dry and semi-arid regions. Plant growth decreases in drought stress. Water shortages in the world and in Iran have always been a limiting factor for plant cultivation. Drought is a common problem that seriously affects the quantity and quality of agricultural products, such as medicinal plants. The use of agronomic techniques, including soil biological conditions (using mycorrhiza and Azospirilum) and the use of chemical fertilizers, may be effective in reducing the effects of drought stress.

In this regard, a field experiment was carried out in two regions of Tehran (semi-arid) and Varamin (arid) in the period of 2014-15. The experiment was split factorial in a completely randomized block design with three replications. The main factor consisted of three treatments without water stress, moderate stress and severe stress (irrigation at 50, 40 and 30 percent of field capacity), and the factorial arrangement consisted of three fertilizer regimes (no fertilizer application, 50 and 100 percent Nitrogen + Phosphorus application requirements for plant), mycorrhizal fungi and Azospirilum bacterium (application and non-application) were considered as a subplot. Drought stress treatments at flowering stage (during flowering until the end of the season) were applied based on soil crop capacity. The following steps were applied to apply water deficit treatments, respectively: First, the field capacity was obtained, first, a plot (length of two meters × two meters wide) from each experimental site completely up to the end of the plain wall of the water filled and was enclosed with plastic (to prevent water evaporation and error) to the soil completely saturated with water. After 48 hours, the water was removed by gravity from the coarse porosity, the plastic was removed from the plots, the soil sample was prepared and, after weighing, in an oven at 105° C for 24 clock was placed. The sample was then calibrated with a precision weighing scale and evaporated moisture content (soil moisture content).

The results showed that grain yield and its components (biological yield, 1000 seed weight, number of seeds per plant, number of capsules per plant and number of lateral branches per plant) with irrigation reduction (moderate and severe), were significantly dry weather in the Varamin area decreased. Inoculation of mycorrhiza with combined application of chemical fertilizers and Azospirillum improved seed yield, biological yield, 1000 seed weight, seed number per plant, number of capsules per plant and number of lateral branches per plant under drought stress conditions in arid and semiarid regions. Biological and grain yield in terms of absence of drought stress along with application of chemical and biological fertilizers to the conditions of severe drought stress, with non-application of chemical and biological fertilizers were 60% and 65% respectively for Tehran region and 50% and 59% for Varamin area increased. Reducing the amount of photosynthesis, reducing carbon dioxide absorption, increasing transpiration and decreasing water absorption, increasing leaf temperature due to reduced transpiration and reduced absorption of food can be mentioned due to reduced biological yield and grain yield under drought stress.

In general, drought stress has reduced the yield and the use of biological fertilizers has caused the plant's resistance to drought stress.