Effects of Water and Nitrogen on Senescence Related Physiological Indexes of Functional Leaves and Yield of Oat

To understand the effects of water and nitrogen on physiological indexes and yield of oat,the leaf senescence related physiological indexes such as SOD activity,MDA content and soluble protein content of flag leaves at different stages,and yield of oat were examined in the controlled condition.The result showed that the interaction of water and nitrogen on leaf senescence related index of oat were restricted by soil moisture.In water stress conditions of W1 and W2,a moderate amount of nitrogen could keep higher SOD activity in the whole growth period,prevent the peroxidation of membrane lipid effectively,reduce the contents of MDA,soluble protein and chlorophyll,delay the aging of cell and improve the adaptability of oat to water stress.While increasing the amount of nitrogen,the effect of nitrogen fertilizer is negative,it could reduce SOD activity and the contents of soluble protein and chlorophyll,increase MDA content,as a result,speeding up the leaf senescence and reducing the yield.In the W3 conditions,nitrogen application could improve the SOD activity,and the contents of soluble protein and chlorophyll obviously,reduce the MDA content,finally delayed the leaf senescence and improved oat yield substantially.When nitrogen amount was up to 180 kg·hm-2,the effects of nitrogen fertilizer reduced.The influence of water and nitrogen on senescence related physiological indexes at different growth periods and yield of oats were at significant or very significant levels,and the interactions between water and nitrogen were very significant.