以‘蜀恢162’(‘Shuhui 162’)、‘糯89-1’(‘Nuo 89-1’)、‘蜀恢162/糯89-1’(‘Shuhui 162/Nuo 89-1’)、‘奇妙香’(‘Qimiaoxiang’)和早黄矮(‘Zaohuang’ai’)5个水稻(Oryza sativa L.)品种(系)为研究对象,采用叶绿素荧光成像系统研究了低温(4℃)胁迫对水稻3叶期幼苗不同叶龄叶片叶绿素荧光特性的影响。结果表明:经低温胁迫处理后,5个水稻品种(系)幼苗3个叶龄叶片的各叶绿素荧光参数变化有明显差异,其中第一叶的各项参数均降至0。经低温处理后5个水稻品种(系)幼苗3片叶片的PSⅡ最大光化学量子产量(Fv/Fm)均明显小于对照(25℃),其中第一叶的降低幅度最大、第三叶最小。经低温胁迫处理后,5个水稻品种(系)幼苗第三叶的非光化学淬灭系数(qN)均显著大于对照,耐冷性品种‘糯89-1’幼苗第二叶的qN较对照显著增大,而其他水稻品种(系)幼苗第二叶的qN均显著小于对照;‘糯89-1’幼苗第二叶的光化学淬灭系数(qP)较对照略有增大,第三叶的qP显著大于对照;‘早黄矮’幼苗第三叶的qP也大于对照但差异不显著,而其余水稻品种(系)幼苗第二叶和第三叶的qP均显著小于对照。经低温胁迫后5个水稻品种(系)幼苗3片叶片的PSⅡ最大相对电子传递速率(rETRmax)和半饱和光强(Ik)均显著小于对照;除‘糯89-1’幼苗第三叶外,5个水稻品种(系)幼苗3片叶片的快速光响应曲线初始斜率(α)也均显著小于对照,总体上第一叶的rETRmax、Ik和α下降幅度最大、第三叶最小。研究结果揭示:受低温胁迫后,叶片自身生理差异是导致水稻幼苗不同叶龄叶片受伤害程度不同的主要因素。

Taking five cultivars ( lines) of Oryza sativa L． including ‘Shuhui 162’,‘Nuo 89-1’,‘Shuhui 162 /Nuo 89-1’， ‘Qimiaoxiang’and ‘Zaohuang’ai’ as the research objects， the effect of chilling stress ( 4 ℃ ) on chlorophyll fluorescence characteristics of leaves with different leaf ages at threeleaf stage seedling was studied by chlorophyll fluorescence imaging system． The results show that after chilling stress， all of chlorophyll fluorescence parameters of leaves with three leaf ages of five cultivars ( lines) have obvious variations， in which， all parameters of the first leaf decrease to 0． After chilling stress， the maximal photochemical quantum yield of PSⅡ ( Fv /Fm ) of three leaves of five cultivars ( lines) is obviously lower than that of the control ( 25 ℃ ) ， in which， decreasing range of Fv /Fm of the first leaf is the largest while that of the third leaf is the smallest． After chilling stress， non-photochemical quenching coefficient ( qN) of the third leaf of five cultivars ( lines) is significantly larger than that of the control． And qN of the second leaf of cold-resistance cultivar‘Nuo 89-1’is significantly larger while that of other cultivars ( lines) is significantly smaller than that of the control． Comparing to the control，photochemical quenching coefficient ( qP) of the second leaf of‘Nuo 89-1’increases slightly and that of its third leaf increases significantly after chilling stress， and that of the third leaf of ‘Zaohuang’ai’is also larger than that of the control but without significant difference， while qP of the second and third leaf of other cultivars ( lines) is significantly smaller than that of the control． After chilling stress， the maximum relative electron transport rate of PSⅡ ( rETRmax) and semi-saturation light intensity ( Ik) of three leaves of five cultivars ( lines) all are significantly smaller than those of the control． Except the third leaf of ‘Nuo 89-1’， the initial slope of rapid light curve ( α) of three leaves of five cultivars ( lines) after chilling stress all are significantly smaller than that of the control． In general， the decrease range of rETRmax， Ik and α of the first leaf is the largest and that of the third leaf is the smallest． It is revealed that the self-physical difference of leaves is a main factor inducing to injury degree variation among different leaves with different leaf ages of O． sativa seedlings after chilling stress．