Effects Of Plant Growth Regulators On Grain Yield, Quality And Physiological Metabolic Process In Wheat (Triticum Aestivum L.) Under The Stresses

The effects of plant growth regulators(PGR) BR and GABA on the grain yield ,quality and physiological metabolism of winter wheat(triticum aestvum L) under the stress of ultraviolet radiation and high temperature in filling stage by using the cultivars NongDa 189 (ND189)and ZhongYou 9507 (ZY9507 ) as experiment materal treated at anthesis stage, and the main results were as following:1. In this experiment, high temperature and ultraviolet radiation decreased the grain yield of two cultivars significantly, and the treatments of PGRs showed alleviate effect on reduction of grain yield in two cultivars. The treatment of BR increased the grain yield of two cultivars under high temperature, and the treatment of GABA increased the grain yield of cv. ZY9507 under high temperature and of cv. ND189 under ultraviolet radiation.2. High temperature impacted the quality of wheat, For example, the gluten content of two cultivars and the total protein content and the sedimentation value of cv. ZY9507. decreased significantly under high temperature. BR increased the gluten content of two cultivars, however, it hardly changed the total protein content and the sedimentation value. GABA increased the wet gluten content but decreased the sedimentation value and dry gluten content of two cultivars. Ultraviolet radiation increased the total protein content and the sedimentation value. BR could increase the gluten content of two cultivars, and it had different effect on the total protein content and the sedimentation value in two cultivars. GABA increased the total protein content and the sedimentation value and gluten content in two cultivars except the sedimentation value and dry gluten content in cv. ND189.3. GABA and BR affected the MDA content, SOD activity and the soluble sugar content of flag leaf in two wheat cultivars under the stresses, which reflected the resistant ability. The MDA content of flag leaf in two cultivars rised under two stresses, but the PGRs decreased it, which showed that the PGRs decreased the degree of super oxidation in membrane. The both stresses decreased the SOD activity of flag leaf in the late stage of filling, GABA increased the activity under high temperature, which showed same effect of reduction in MDA content. The two treatments decreased the SOD activity in two cultivars, which showed adverse effect in high temperature. However, the result of sugar content showed that high temperature increased the content of soluble sugar, and GABA and BR decreased it. Ultraviolet radiation decreased the soluble sugar of flag leaf in cv. ND189, the both treatments increased it. which showed that the treatment of PGR might enhance the membrane by regulating the endosmosis4. BR and GABA may build up the resistant ability to high temperature and ultraviolet radiation by altering the level of phytohormone in tissue of wheat. For example, GABA and BR increased the IAA content in filling stage and the ABA content in the later, which could enhance the synthesis and export of assimilates, and the PGRs increased GA3 content and delayed or increased ABA content ,which benefit the development of grain.