Mechanism Of Enhancing Drought Resistance Of Wheat From Seeds Soaked With Ca+GA

The 47 to 52.5 percent of Chinese territory belongs to arid or semi-arid area. The damage of drought to crop is the most serious in all non-biological stress and it is just inferior to the damage brought by plant diseases and pests. Studying and popularizing chemical water-saving and drought-resisting technology is an effective method to defend the drought The previous research showed that seed-soaking treatment with the mixture of calcium chloride (CaCl2) and gibberellin (GA) could promote the seeds' germination and seeding growth under drought condition. The reason is that the mixture application of Ca and GA played an intersupplement role in both metabolism and growth of crops. The author treated the seed of winter wheat (Triticum aestivum L. yumai 49) with the mixture of calcium chloride (CaCl2) and gibberellin (GA) to find the mechanism of enhanced drought-resistance of this seed-soaking treatment by investigating the content of osmotic adjustment matter and the activity of antioxidative system under simulative drought condition with 20 percents PEG6000 solution (osmotic potential is -0. 59MPa).The present experiment showed that calcium chloride (CaCl2) hasn't significant positive effect on the seed's germination under drought stress. But it significantly increased the soluble protein content in the embryo from the first day after sowing to the fifth day. These soluble proteins perhaps play important role as the osmotic adjustment matter and the drought-induced protein. The germination of the wheat's seed under drought stress was significantly increased when soaked with 50mg/L gibberellin (GA). It can be contributed to the maintenance of tougor pressure and energy which embryo needs since pro and soluble protein content in the embryo as well as the pro and soluble sugar content in the endosperm were all increased in this treatment. The seed soaked with 0.5 %CaCl2+50mg/L GA also showed markedly increased germination under drought stress, and the shoot growth significantly increased by reducing the root/shoot ratio in the ninth day. Ca+GA seed-soaking and GA seed-soaking showed similar mechanism in promoting the wheat seedling drought-resistance. They both enhanced wheat seedling drought-resistance by increasing pro and soluble protein content in the embryo as well as promoting pro and soluble sugar content in theendosperm. Differing from the CK and the CaCl2 soaking seeds, the seeds soaked with GA or Ca+ GA reduced the sensitivity of embryo to drought which is attained through maintenance the embryo's tougor pressure and it's energy metabolization level in growing. The antioxidant system of embryo in seeds soaked with Ca+Ga kept at a lowest lever than CK, CaCl2 treatment alone and GA treatment alone. So Ca+GA seed-soaking treatment kept the oxidative state of embryo in a lowest level and favored seedling establishment under drought conditions.