不同产量水平玉米杂交种生育后期光合效率比较分析

Analysis of Photosynthesis Efficiency of Maize Hybrids with Different Yield in the Later Growth Stage

大田条件下 ,玉米的光合速率 (Pn)受光子流密度 (PFD)的影响要大于受二氧化碳浓度 (Ca)的影响 ,并且对PFD和 Ca的响应也存在着差异。最大光化学效率 (Fv/ Fm )、实际光化学效率 (Φ PS )、光合速率 (Pn)、非光化学猝灭(NPQ)和光化学猝灭系数 (q P)存在着明显的日变化。其中 Fv/ Fm、Φ PS 、 q P呈倒抛物线型日变化 ,在中午强光下降低到一天中的最低值 ,且乳熟期大于蜡熟期 ;Pn、 NPQ则呈抛物线型日变化 ,在中午时分达到一天中的峰值 ,NPQ蜡熟期大于乳熟期。不同产量水平玉米杂交种的 Fv/ Fm、Φ PS 、 q P、 Pn、 NPQ变化也存在着明显差异 ,产量水平高的杂交种 YY2 3具有较高的 Fv/ Fm、Φ PS 、 q P、 Pn 和较低的 NPQ,产量水平低的杂交种 YY5具有较低的 Fv/ Fm、Φ PS 、 q P、 Pn 和较高的 NPQ,这些差异在日变化中以中午时分尤为明显 。

The photosynthetic efficiency of maize hybrids with different yield in the later growth stage was investigated through measurements of photosynthetic rate and chlorophyll fluorescence parameters of photosystem Ⅱ using a portable CIRAS 1 photosynthetic gas analysis system and portable fluorescence monitoring system (FMS2). In the field condition, photon flux density(PFD) had greater influence on net photosynthetic rate (P n) than CO 2 concentration (C a) in two hybrids, and there existed difference between the response of P n to PFD and C a in the same hybrid. The declines in maximal photochemical efficiency of PSⅡ in the darkness(Fv/Fm), actual photochemical efficiency of PSⅡ in the light (ΦPSⅡ) and photochemical quenching co efficient(qP) were observed at midday strong sunlight. The 3 indexes in the milky stage were higher than that in the doughy stage. On the other hand, photosynthetic rate (P n) and non photochemical quenching (NPQ) amounted to maximum value at midday. The value of NPQ in the doughy was higher than that in the milky. All the 5 indexes showed different between two hybrids. Higher yield hybrid YY23 had higher Fv/Fm, ΦPSⅡ, qP, P n and lower NPQ when compared with lower yield hybrid YY5. The difference of those parameters at midday was especially obvious, and larger difference displayed in the doughy than in the milky stage.