极端温度对籼粳稻苗期光合特性及生理生化特性的影响

Effects of extreme temperature on photosynthetic and physio-biochemical characteristics of indica and japonica rice seedlings

以籼稻9311和粳稻日本晴为材料,研究了极端温度胁迫下和恢复期材料苗期的光合特性、保护性酶活性及其他生理生化特性的变化.实验结果表明:极端温度胁迫使2个材料叶片的净光合速率急剧降低,但是高温胁迫后9311净光合速率的恢复速度明显高于日本晴,后者在低温处理后恢复较快.极端低温使9311光系统Ⅱ的最大光化学效率(Fv/Fm)降低,而对日本晴影响很小,两者均在处理后1 d完全恢复;极端高温处理对于光系统Ⅱ的伤害更为严重,Fv/Fm持续下降直到恢复期第1天,到处理后第4天才恢复到正常状态,与日本晴相比,高温处理使9311的Fv/Fm下降的程度更大,但其恢复也快.极端温度胁迫下叶片叶绿素含量和植株水分含量都下降,丙二醛含量上升,保护性酶超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性升高;总抗氧化能力受极端温度胁迫而降低,在恢复期升高;低温胁迫时日本晴的SOD和CAT活性、总抗氧化能力高于9311,高温处理下则相反.上述结果表明叶片的光合速率、叶绿素荧光参数、保护性酶活性均可作为水稻耐温度胁迫的筛选指标,但是光合速率宜在恢复期测定,而叶绿素荧光参数在处理时测定较为有效.

Indica rice 9311 and japonica rice Nipponbare were used to study their photosynthetic characteristics, protective enzymes activities, and several other physio-biochemieal characteristics changes under the stress of extreme temperatures and the following recovery period. Results showed that the net photosynthetic rate of the two materials under extreme temperature stress decreased dramatically, while during the recovery period, the net photosynthetic rate of 9311 was higher after hot stress and lower after cold stress than that of Nipponbare. Potential photochemical efficiency （Fv/Fm ） of 9311 leaves declined more severely than Nippon- bare under cold stress, however, both of them recovered fully one day later. PS I1 was injured more seriously under extreme high temperature stress, but it suggested that we might investigate Fv/Fm at the end of temperature stress, and the net photosynthetic rate during recovery period than that under lower temperature. Fv/Fm decreased obviously under the extreme high temperature stress, and continued to decline during the following day, and recovered completely after stress. On the fourth day Fv/Fm of 9311 declined more and recovered faster than that of Nipponbare after high temperature stress. Under extreme temperature stress, leaf chlorophyll content and plant water content decreased, while the level of malondialdehyde （ MDA ） , and protective enzymes SOD and CAT activities increased. However, the total antioxidant oxidative capacity （ T-AOC ） reduced under stress of the extreme temperature, but increased during the recovery period. 9311 plant exhibited lower SOD, CAT and T-AOC activities and higher MDA lever than Nipponbare under low temperature. On the contrary, the former had higher protected enzymes and lower MDA than the latter. These results suggested that the net photosynthetic rate, Fv/Fm, SOD, CAT and T-AOC activities were all criterions for selecting low or high temperature resistant materials. However, it suggested that we＇d better investigate leaf gas exchanges during recovery days, while measure Fv/Fm at the end of stress.