Effects Of Leaf Orientation On Photoinhibition And Senescence In Rice

mid-maturing indica rice Yangdao 6, with leaf-drooping and leaf-curling treatments, was used as material to investigate the effects of leaf orientation on photoinhibition and senescence, the results show that: (1) different leaf-orientations have different photosynthetic active radiation and leaf surface temperature, in these leaf types, the drooping leaf can get the largest amount of photosynthetic radiation and leaf temperature maximum, followed by flat leaf, and then the roll leaf. (2) photoinhibition and hoto-oxidation degree in drooping leaf are the greatest for the chlorophyll fluorescence parameters Fv/Fm (maximum PSII photochemical efficiency) have the most rapid decline; Similarly, its superoxide anion and hydrogen peroxide production rate is also the largest. In contrast, photoinhibition in roll leaf is relatively small. (3) drooping leaf has greater advantages in photosynthetic rate in the early period of grain-filling stage, but with the development process,its photosynthetic rates decline faster than the other two leaf types, making its photosynthetic rate in late period of grain-filling stage much lower (4) chlorophyll content in drooping decreases fast, with the process of grain-filling, resulting later start of filling in inferior grains, but the difference of grain weight among drooping leaf and the other two leaf types is not significant. The decline in leaf chlorophyll content and rate of grain filling process the same in drooping leaf and normal flat leaf plants, there is no particular advantage or disadvantage in roll leaf plant.