【摘要】 水稻中存在着光抑制现象,经1987—1989年三年观察及试验,进一步看到广东种植的水稻在下列三种自然光温条件下会发生明显的光氧化现象:1.早稻苗期:长期低温阴雨突然转晴;2.早稻中期:长期阴雨突然烈日当空;3.晚稻灌浆期:冷空气南下后,出现晴天。用LI—6200手提式光合作用测定仪对田间水稻光合作用日变化的测定表明,广东推广种植的桂朝2号及七桂早在晴天中午有明显的光抑制现象,尤以在氮肥不足情况下更为严重。且经中午强光照射后其光合能力明显受到损伤,下午光强减弱后不能恢复到正常水平。人工气候箱中模拟光抑制诱导条件的试验还证明:Lemont及其杂种稻Le/QI抗光抑制能力明显比桂朝及七桂早为高。另外优良的肥水条件也有利于减轻光抑制的危害。因此有可能通过育种及栽培途径避免光抑制,提高对强光的光能利用率,从而达到提高水稻生产力的目的。更多还原

【Abstract】 Observations and researches were carried out to understand whether photoinhibition(PI) and photooxidation (PO) would appear in field growing rice plants under natural conditions in Guangdong and to understand the varietal characters and cultivation conditions in relation to the damage of PI and PO as well as the potential of increasing rice productivity. LI-6200 Portable Photosynthesis System and ADC 225 infrared gas analyser were used for the measurement of photosynthesis in the field and quantum yield(QY) in laboratory. It was observed in 1987,1988,and 1989 in the field that PO, which was characterized by chlorophyll destruction and QY decrease, would appear under following three conditions: 1, Long-term low temperatures accompanied by cloudy and rainy days were followed by a sunshine day;2,Long-term cloudy and rainy days were followed by a full sun-syine day; 3, While cold wind came to Guangdong, if was a clear day (Fig. 1) . Measurement of diurnal changes of photosynthesis in field growing rice plants demonstrated that maximum photosynthesis could decrease even by 60-70% at 1400-1500 for Guichao 2 and Qiguizao ,especially under low nitrogen conditions,but it was not severe for Lemont and its hybrid rice Lemont/Qiguizao (Fig. 2). The phenomenon of "midday depression "of photosynthesis couldn’t be simply explained by changes in stomatal conductance,and might be related to PI caused by the strong light at midday. Our experiments on pot rice plants treated with "low light→high light","low temperature+high light","low nitrogen+high light"and "water stress+high light"also proved the magnitude of PI and PO damage among different rice varieties was quite different (Fig. 5,6) ,and that nitrogen deficiency and water stress would exacerbate the damage caused by strong light(Fig. 7,8). Because photosyn-thetic efficiency under high light is considerably lower than that under low light,there is a great potential to improve light use efficiency by breeding and cultivation to increase the adaptability of rice to high light and,therefore,to increase productivity.更多还原