Studying of Seed Priming and Water Stress Effects on Growth and Yield of Sunflower Nuts (Helianthus annuus L)

Water stress is one of the most important environmental stresses that affect the germination, growth and yield of plants. Seed priming is a technology that positively influences seedling establishment in many crops and may improve field performance under adverse environmental conditions. Seeds can be primed using different media such as tap water (hydro-priming), low water potential solutions (osmo-priming) such as polyethylene glycol or salt solutions, solid matrix (matri-priming), and plant growth regulators (hormonal priming). Nitroauxin and auxin are the rich source of macro-nutrients, micro-nutrients, vitamins, enzymes and hormones of plant growth promoters. Therefore, the use of these media in sustainable agriculture causes the rapid growth of oil seed plants. Limited information is available about the response of sunflower under water deficiency conditions in priming, so the aim of this research was to study the growth and yield of these species under these conditions. An experiment was conducted in 2014 at the field research station of the Faculty of Agriculture of Azerbaijan Shahid Madani University, Iran. The experiment was laid out as a randomized complete block design arranged in a factorial with three replications. Priming factor included (water treatment and nitro auxin, water and auxin, hydro-priming and control (without priming)) and factor water stress include (stress during stem stage, stress during grain filling stage and control (normal)).The seed priming 48h before sowing were treated with the water and nitro auxin, water and auxin and hydro-priming for 16h, after priming, seeds are air-dried back near to the original weight. Seedlings planted by hand on 2 may 2014 by density of 38000 plants ha-1 (60×30 cm). Weeds were controlled by hand during crop growth and development as required. At maturity, five plants randomly were harvested from each plot and plant growth rate, head growth rate, head diameter, No. of seed per head, 1000 seed weight, seed yield per plant and kernel to grain ratio, husk to grain ratio and percentage of unfilled seeds were recorded. The data were analyzed by SPSS 16 software. The means were compared using the Duncan multiple range test at p ≤0.05. Excel software was used to draw figures. Analyses of variance of the data showed that all traits were affected by water stress and seed priming main effects. Priming of seeds increased significantly the absolute growth rate, head diameter, grain number, 1000 seeds weight, grain yield and kernel to grain ratio and husk to grain ratio was reducing the percentage of unfilled seeds per head. Water stress also reduces all traits except unfilled seeds per head, which enhances it. Water stress at the grain filling stage was causing the most reduction of grain yield per unit area.
The increase in growth and yield of sunflower with seed priming treated nitro auxin and auxin could be due to the fact that by promoting germination and providing more uptakes of phosphorus and nitrogen. Reduction in the growth and yield under water stress could be the result of a preferential allocation of biomass production to the roots or a reduction in chlorophyll content and, consequently, photosynthesis efficiency. Seed yield decreased on account of water deficit stress. Decrease in seed weight and increase in unfilled seeds were the main reasons for decreasing in seed yield. Decrease in seed yield due to decrease in yield components, especially seed weight has been reported by other researchers previously. The increase in Percentage of unfilled Seeds under water stress could be due to the fact that water stress effect on available assimilates during seed filling stage and decreases sink capacity and leads to unfilled seeds and low seed weight. In conclusion, this study showed that application of seed priming play useful role in improving the growth, yield and performance components of sunflower, and also the seed priming with auxin and nitro auxin, were better than seed hydro-priming, this can be related to the chemical properties of these compounds. The results of this study indicate that pre-treatment of seeds are effective in increasing yield and yield components of sunflower seeds in order to avoid adverse effects of water stress.