With indica (Oryza sativa L.) hybrid Shanyou 63 as control, the hybrid rice varieties including Peiai 64S/E32, Peiai 64S/9311,X07S/Zihui 100,Guangyou 881 and japonica 9516 were used to study changes of chlorophyll content, photosynthetic response to light intensity and temperature, chlorophyll fluorescence characteristics and membrane lipid peroxidation in their flag leaves at the late stage of development under natural conditions in Nanjing. The results were as follows: primary photochemical efficiency of PSⅡ （Fv/Fm）, quantum yield of linear electron transport of PSⅡ (ΦPSⅡ), electron transfer rate (ETR) in these rice varieties decreased with their decrease of chlorophyll content during this period. This kind of impediment to energy conversion induced the transfer of excessive energy to the reducing side of PSⅠ, hence the accumulation of O[SX(B-*3]-[]·[SX)]2 and peroxidation of membrane lipid, and resulting in the accumulation of malondialdehyde (MDA), that is the destroys of photosynthetic pigments and membranes and the consequent, premature senescence. This phenomenon is variable conspicuously in different rice varieties. Under natural condition in Nanjing,Fv/Fm,ΦPSⅡ, ETR and quenching coefficient(qP) in japonica 9516 tolerant to photooxidation decreased less and the conversion capacity of light energy was stable, premature senescence was unlikely , and consequently the seed setting rate was higher. While Fv/Fm, ΦPSⅡ,ETR and photochemical qP in Shanyou 63 sensitive to photooxidation decreased more and therefore premature senescence was easy to happen, thus the seed setting rate and yield were all reduced. The tolerance to photooxidation and premature senescence in other hybrids derived from typical two line or three line crossing laid in the middle. From the rice breeding for super high yield, on the basis of the good plant type of current rice, considering both hybrid vigor and the prevention premature senescence, it would be a notable strategy to use japonica maternal line or maternal lines with some japonica genotype as the sterile lines in rice breeding.
自然条件下不同高产稻生育后期剑叶叶绿素荧光和膜脂过氧化的表现
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