去除遮阴后自然强光对小偃54和8602及其杂交后代光合特性的影响

Effects of Full Sunlight after Shading on Photosynthetic Characteristics of Xiaoyan 54 and 8602, and Their Hybrids

黄淮地区冬小麦生育后期常出现阴雨寡照及连阴骤晴等不良气候,本试验目的是阐明弱光逆境解除后自然强光对冬小麦光合特性的影响。在抽穗至开花期对小偃54和8602及其杂交后代小偃81和212遮阴处理(约自然光40%),10 d后去除遮阴,测定恢复过程中亲本与杂交后代旗叶叶绿素含量、光合气体交换、叶绿素荧光等参数。去除遮阴初期,亲本与杂交后代都发生了光抑制,净光合速率(Pn)、叶绿素a/b比值、胞间CO2浓度(Ci)、气孔导度(Gs)、光系统II(PSII)最大量子效率(Fv/Fm)、PSII实际光化学效率(ΦPSII)、非光化学猝灭(NPQ)和电子传递到QA下游的概率(Ψo)都低于对照,并且随着去除遮阴时间的延长逐渐恢复。杂交后代小偃81在去除遮阴后比其2个亲本和另一杂交后代品系212具有相对更高的Pn、ΦPSII和Ψo,表明小偃81对环境光强变化的适应性优于其亲本,且相对较高的PSII光化学效率活性和稳定性是其在去除遮阴后拥有更高Pn的原因之一。小偃81更能适应黄淮地区小麦生育后期光照不足和连阴骤晴的不良气候。

Shading problem often occurs at the late growing period of winter wheat in the Huang-Huai Plain of China. The objective of this study was to explore the effect of full sunlight after the shading treatment on photosynthetic characteristics in wheat. In a filed experiment with 10-day shading（40% of natural light intensity） from heading to anthesis, the photosynthetic characteristics of wheat varieties Xiaoyan 54 and 8602 and their hybrids Xiaoyan 81 and 212 were measured at 0, 1, 3, 5, 7, and 10 days after shading treatment. Photoinhibition was observed in all genotypes when the shading ended, and the photosynthetic rate（Pn）, ratio of chlorophyll a to chlorophyll b, intercellular CO2 concentration（Ci）, stomatal conductance（Gs）, maximum quantum yield of PSII（Fv/Fm）, actually photochemical efficiency of PSII（ΦPSII）, nonphotochemical quenching（NPQ） and efficiency that an electron moves to QA downstream（Ψo） were lower than that of the control（no shading treatment）. However, such reductions were alleviated gradually with the time lasting after shading. The hybrid Xiaoyan 81 had the highest Pn, ΦPSII, and Ψo as compared with other tested genotypes, showing its good adaptability to the change of light intensity. The higher Pn in Xiaoyan 81 than in its parents after shading probably resulted from the higher photochemical efficiency of PSII in Xiaoyan 81. These results suggest that Xiaoyan 81 is a wheat variety suitable to grow in the Huang-Huai Plain with low light intensity problem at late growth period of winter wheat.