Changes In Nutrients In Leaves Of Rice During Senescence And Leaf Senescence

The total chlorophyll content, net photosynthesis rate, total sugar content, total nitrogen content, the activity of SOD and CAT of flag leaves of rice during sneescence was compared between two rice cultivars, i.e. Shanyou 63 (SY63) and Liangyoupeijiu (LYP9), with different source-sink ratio. The effects of light and dark treatments and different sugar-feeding treatment on leaf senescence were also investigated using detached rice leaves. The results showed as followings:1. The leaves planted in substrate in light are delayed in leaf senescence compared with that shaded during two days after planted. The various consistency of substrate take some effect on leaf senescence, and thicker consistency of sugar can delay leaf senescence.2. The total chlorophyll content of the leaves of 1/2 spikelet removal rice is higher than that of check, and the total chlorophyll content of the leaves of defoliation rice is lower than that of check, during middle and later of gain filling. The total chlorophyll content of the leaves under NH/-N is higher than that under NO3-N.3. The net photosynthesis rate of the leaves of 1/2 spikelet removal rice is lower than that of check, and the net photosynthesis rate of the leaves of defoliation rice is higher than that of check, during beginning of gain filling. The net photosynthesis rate of the leaves of 1/2 spikelet removal rice is higher than that of check, and the net photosynthesis rate of the leaves of defoliation rice is lower than that of check, during later of gain filling. The net photosynthesis rate of the leaves under NH4+-N is higher than that under NO3--N.4. The total sugar content of the leaves of 1/2 spikelet removal rice and the leaves of defoliation rice is higher than that of check, and which of the leaves of 1/2 spikelet removal rice is lower than that of defoliation rice. The total sugar content of the leaves of 1/2 spikelet removal rice is higher than that of check, and total sugar content of the leaves of defoliation rice is lower than that of check, during middle and later of gainfilling. The total sugar content of the leaves under NH4+-N is higher than that under NO3-N.5. The total nitrogen content of the leaves of 1/2 spikelet removal rice is higher than that of check, and the total chlorophyll content of the leaves of defoliation rice is lower than that of check, during middle and later of gain filling. The total nitrogen content of the leaves under NH4+-N is higher than that under NO3--N.6. The activity of SOD and CAT of the leaves of 1/2 spikelet removal rice is higher than that of check, and the activity of SOD and CAT of the leaves of defoliation rice is lower than that of check, during gain filling. The activity of SOD and CAT of the leaves under NH/-N is higher than that under NO3--N.According to the above results and integrateing result of other peoples, it was suggested that altering sink-source rate take some effect on leaf senescence, the leaves of 1/2 spikelet removal rice are delayed in leaf senescence compared with check, the leaves of 1/2 spikelet removal rice are accelerated in leaf senescence compared with check, the leaves under NH₄⁺-N are delayed in leaf senescence compared with leaves under NO₃--N.