Effects Of Triadimefon On Growth And Physiological Chracteristics Of Soybean Under Drought And Rewatering At Flowering Stage

The soybean is one of the important oil crops in China. It needs much water and is more sensitive to water deficit. In recent years, due to global climate change, drought happens frequently. The drougth stress has already become the major limited factor on yield and quality of soybean. Plant growth regulators can alleviate the stress of soybean caused by drought, and reduce the decrease in yield of soybean. In this study, Nannong99-6(Glycine max var. Nannong99-6) and Kefeng1(Glycine max var. Kefeng1) were used to study the effect of triadimefon on growth and physiological characters under drought and recovery with pot experiment. The result will help to elucite the resistant mechanism of triadimefon and give some new sights for drought-resistant cultivation. The main result is as follows:1. The plant height, shoot dry weight, root dry weight, grain yield and yield components were significantly decreased under drought stress with Nannong99-6, while it was not significant for Kefeng1. Activity of SOD, POD and content of GSH, AsA in both varieties were significantly increased by drought, while the leaf relative water content and Car content were decreased. Meanwhile, H2O2, MDA contents, the production rate of O2-and the value of EL in soybean’s leaves under drought conditions were significantly increased. The increasing amplitude of Nannong99-6was bigger than Kefeng1, and there was no significant difference under normal water conditions.The study also showed that the photosynthetic parameters were significantly decreased, but SS, SPS activity were increased under drought resistance. Glucose, sucrose, soluble sugar and starch content were increased in the early drought period, with increasing of water stress, sugar content was decreased. Drought stress increased GS, NR activity, soluble protein, NH4+-N, N03--N content, with increasing stress, there was a downward trend. Results also showed that ABA, GA content increased in leaves under drought, while there was no significant difference for IAA.2. The plant height and leaf relative water content were significantly reduced by triadimefon in Nannong99-6and Kefeng1. Triadimefon improved the biomass, chlorophyll content and yield, but didn’t reach a significant level for Kefeng1. A lot of new born and short roots were found in treatment of triadimefon, meanwhile, the number of mitochondrion in root tip cells was significantly higher than non triadimefon treatment. In vacuoles, there were a lot of electron-dense precipitates in triadimefon treatment. Under drought conditions, POD, SOD activity and GSH content were increased but AsA content, ROS accumulation, lipid peroxidation were decreased by triadimefon. The change amplitude of Nannong99-6was bigger than Kefeng1, and there was no significant difference under normal water conditions.Triadimefon pretreatment significantly increased SS, SPS activity, photosynthetic parameters and promote the accumulation of sugar content under drought stress. NR activity, soluble protein and NH4+-N, NOs--N content were increased while GS activity was decreased by triadimefon. The study also found that triadimefon reduced GA, ABA content and GA/IAA, GA/ABA under drought conditions, but under normal moisture conditions improved GA, IAA content and IAA/ABA in soybean leaves.3. MDA content was significantly decreased and even lower than normal water treatment after re-watering. AsA content was still significantly higher than normal control in Nannong99-6. SOD activity remained at a high level in Kefeng1, while other indexes of carbon and nitrogen metabolism recovered to the normal water level after re-watering.Triadimefon promote shoot and root growth of two varieties of soybean and GSH and Car content remained at high level after re-watering. We also found that SPS activity, photosynthetic parameters, starch content, IAA content and IAA/ABA remained relatively high level, but sucrose content decreased significantly by triadimefon after re-watering. That triadimefon can maintain the functional leaves and delayed senescence senesce.