Photosynthetic And Physio-Biochemical Characteristics Investigated On The Leaves At Each Position Of Different Rice Varieties

Rice produces organic matter in process of photosynthesis that is closely related to biological yield. In this study, the leaf photosynthetic and physio-biochemical characteristics of Japonica rice varieties ER145and Xiushui09, indica rice variety9311were investigated under the natural conditions. The CO2assimilation rate against Ci and chlorophyll fluorescence induction dynamics curve JIP in leaves of each position of the three Rice varieties were determined in flowering and grain filling stages; the contents of chlorophyll, nitrogen, proline, MDA and antioxidase activity were measured in leaves at different positions in the two periods respectively. Leaf area and leaf dry weight of different stages of20days and40days after transplanting, flowering and15days after flowering and the grain yield were also evaluated, respectively. The main results were as follows:1. Photosynthetic parameters Vcmax and Jm of each positions leaves of ER145, Xiushui09and9311decrease in turn from the top leaf (the first leaf) to the bottom leaf(the sixth or fifth leaf) at flowering and grain filling stage, and in a larger extent for lower leaves. The same position leaves of the three rice varieties performance were inconsistent at photosynthetic parameters between flowering and grain filling stage. It doesn’t have much difference in Vcmax of ER145the same position leaves between the two periods, The Jm of upper leaves were bigger in grain filling stage than that in flowering period, while the Jm of lower leaves were smaller in grain filling stage than that in flowering period. Xiushui09had a smaller Vcamx and Jm for the lowest two leaves in grain filling stage than those in flowering period.9311also had a similar situation,while its reduction amplitude was higher than Xiushui09.2. During flowering period and grain filling stage, limitation of electron transfer of PSII increases gradually for leaves from the first leaf to the sixth leaf in the three rice varieties, with the extent for lower leaves of9311were higher than those of ER145and Xiushui09in grain filling stage.3. Nitrogen content in each leaf in various locations reduced gradually in turn in both flowering and grain filling period, while nitrogen content at grain filling stage was lower than those at flowering stage. Chlorophyll content in the fourth leaf and the fifth were significantly less than those in upper three leaves of9311, in the fifth leaf and the sixth were slightly less than those in upper4leaves of ER145and Xiushui09in grain filling period. Proline and MDA content, antioxidase SOD, POD increase in the fourth lower leaves than upper leaves, and enzyme activity of each leaf were higher than those in flowering period.4. Leaf area and leaf dry weight in each leaf positions of9311were all larger than those of ER145and Xiushui09. The area and dry weight of bottom leaves of9311in the filling period were less than those in flowering period, and the decrease margin were bigger than Xiushui09and ER145. In addition, grain and biological yield:9311>Xiushui09>ER145.