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.
李霞1,2 焦德茂2* 刘友良1 黄雪清2
以籼型(Oryza sativa L.)杂交组合汕优63为对照,以中粳9516、两系亚种间杂交组合培矮64S/E32、培矮64S/9311、亚种间三系杂交稻冈优881和两系杂交组合X07S/紫恢100为材料,研究其在生育后期(抽穗-成熟)自然条件下剑叶的叶绿素衰减、CO2交换、叶绿素荧光参数和膜脂过氧化表现.结果表明: 水稻在生育后期伴随叶绿素衰减,其叶内的原初光化学效率Fv/Fm、PSⅡ非环式电子传递效率ΦPSⅡ、电子流传递速率ETR都有相应地下降,这种光能转化的障碍使多余的光能传递给PSⅡ的还原侧,产生O(-)/(*)2累积,发生膜脂过氧化和MDA的积累,引起光合色素及光合膜的破坏,发生光氧化早衰.这种现象在品种间有明显差异,耐光氧化的粳稻9516,其叶内的 Fv/Fm、ΦPSⅡ、ETR、qP下降较少,具有较稳定的光能转化能力,不易早衰,具有较高的结实率;而对光氧化敏感的籼稻汕优63其叶内的Fv/Fm、ΦPSⅡ、ETR,光化学猝灭参数qP下降较多,易发生膜脂过氧化,导致叶片早衰,影响水稻灌浆结实和产量;而二系的和三系的杂交稻的耐光氧化特性和早衰表现居于中间.从水稻超高产育种的角度出发,在目前株型良好的基础上,兼顾杂种优势和防止早衰两方面考虑,在母本中利用粳型或带有粳型基因的不育系是育种上一个值得重视的策略.
关键词 早衰 光氧化 荧光特性 膜脂过氧化 水稻
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