The effect of nitrogen-fed on rice (Oryza sativa L.cv.tarom) leaf Senescence

Nitrate and ammonium ions are the two major forms of nitrogen that taken up by plants, but they differ in their effects on growth and chemical composition of biochemical levels. In this research we examined the effect of nitrogen sources on growth and senescence of rice leaves in biochemical levels. Our results showed that amounts of fresh and dry weights, total chlorophyll, rate of Hill^,s reaction, amount of soluble proteins and specific activity of peroxidase significantly were lower in nitrate-fed plants than ammonium-fed plants. Where as, chlorophyll a and chlorophyll b ratio and specific activity of superoxide dismutase were higher in nitrate-fed plant as compared to ammonium-fed plants. Any changes in lipid peroxidation under different treatments of nitrogen means that nitrogen-fed did not induce oxidative stress and senescence in rice plant, but it can only cause reduction in growth parameters such as fresh and dry weights, amount of chlorophyll and protein in nitrate-fed rice plant.