Effect And Mechanism Of Plant Polysaccharides Compound Agents On Crop Growth And Yield

Plant growth regulators and plant hormones have the similar physical and biological effect, which can play an important physiologic function on plant growth, development and metabolism in a low concentration. In the recent years, with the continuous application and further research in plant growth regulator, the scope, scale and effectiveness of plant growth regulators have been rapid developed, especially in such areas as the traditional agriculture can not solve the problems. Plant growth regulators have become a important protection technologies on crop yield, quality and efficient, and play an increasingly important role.New safe and nontoxic plant polysaccharides compound agents, as as plant polysaccharides/ trace element compound agent (PW), plant polysaccharides/ trace element/ photosynthetic promoting compound agent (PWZ) and plant polysaccharides/ trace element/ photosynthetic promoting/ internode inhibition compound agent (PWY) were used in this study. The chlorophyll content, nitrate reductase activity, photosynthetic characteristics and grain filling process of winter wheat were studies in field experiment, with the aim of determining the effects and mechanisms of three plant polysaccharides compound agents, on the growth and grain yield of winter wheat and soybeans after foliage spraying in the flowering stage. The main results and conclusions were listed as the follows:1. The net photosynthetic rate and stomatal conductance of flag leaves in winter wheat were increased in the early stage with the application of plant polysaccharides compound agents. The leaf water and CO2 exchange were promoted, which induced to the improvement of photosynthetic efficiency and formation of photosynthetic products. In the late stage, the decreases of net photosynthetic rate were delayed in the agent treatments, and the photosynthesis was prolonged in flag leaf. The increase of transpiration rate in the later stage could provide the impetus for the migration of photosynthetic products, which was helpful to high grain yield.2. After spraying polysaccharides compound agents for 10 and 7 days, the chlorophyll contents of winter wheat and soybean were significantly increased, and the decrease of chlorophyll contents with crop growth and development were decayed.3. After spraying polysaccharides compound agents, the soluble sugar contents of stems and leaves and crose content of flag leaf in winter wheat were improved in the agent treatments in the early grain filling stage. The decrease of soluble sugar contents of stems and leaves in the later stage were helpful to the distribution of sugar to the grain. The changes of soluble sugar content of spike in four treatments were almost the same, and the soluble sugar content of the agent treatments were higher than the control in the early stage, while opposite results were observed in the late stage.4. The dry matter formation and accumulation of soybean were improved in the agent treatments, and the distribution of dry matters were promoted from stems and leaves to pods. The grain filling rates of winter wheat were also increased in the middle and late stage of grain filling process, with the application of compound agents. 5. The plant polysaccharide compound agents would affect crop yield components to different degrees, the grain weight and grain yield of winter wheat and sotbean were increased by 3.6%~13.4% and 5.9%~12.2%, resprctively. The increasing effects were according to PWY>PW>PWZ.6. The plant polysaccharide compound agents could improve crop photosynthetic capacities, and therer were not significant differences in different agtent treatments. For the day matter accumulation, PWZ would promoted the growth of stems and leaves in the early stage, with consuming part of the photosynthetic product; while PWY would inhibited the growth of stems and leaves in the early stage, with the increase of dry matter accumulation, which observed with the maximum dry weight and promoted the migration of dry matter to grain. It was initially considered that PWY was the best agent, for its high grain yield capacity...