在大田栽培条件下，以冬小麦（Triticum aestivum L.）弱筋品种宁麦9号和中筋品种扬麦10号为材料，研究了不同氮、钾施肥水平下花后旗叶叶绿素含量（SPAD）、净光合速率（Pn）和荧光参数的变化特征及其与开花期叶片氮、钾营养的关系。结果表明，与不施氮、钾的对照（N0K0）相比，施氮、钾肥增加小麦开花后旗叶SPAD和Pn，提高PSⅡ最大光量子产量（Fv /Fm）、潜在光化学活性（Fv /Fo）、有效光量子产量（Fv’/Fm’）和实际光量子产量（ΦPSⅡ）等叶绿素荧光参数，其中氮肥效应高于钾肥。除SPAD外，扬麦10号的Pn及叶绿素荧光参数（Fv /Fm、Fv /Fo、Fv’ /Fm’和ΦPSⅡ）均高于宁麦9号。相关分析表明，Fv /Fm、Fv /Fo、Fv’/Fm’和ΦPSⅡ等叶绿素荧光参数受开花期叶片氮/钾比的显著影响，是施氮、钾肥提高净光合速率的主要生理原因，较高的光能转化特性是满足扬麦10号较高能量需求的生理基础。
Grain yield limit is one of the main problems in medium or weak gluten wheat production in middle-lower reaches of the Yangtze River of China. Nitrogen and potassium are key factors affecting leaf photosynthesis, and previous researches have showed that the application of either of the two fertilizers can improve wheat organ construction, therefore, affect grain yield. However, the physiological mechanism of nitrogen and potassium interaction on photosynthetic characteristics in wheat needs to be revealed. In the present study, we used two winter wheat (Triticum aestivum L.) cultivars, ‘Ningmai 9’ (weak gluten) and ‘Yangmai 10’ (medium gluten) in a field experiment to investigate chlorophyll content (SPAD), net photosynthetic rate (Pn), chlorophyll fluorescence parameters of flag leaves and the relationship among those parameters and nitrogen and potassium fertilization levels. In the experiment, nitrogen was the main plot with 3 levels corresponding to 0, 112.5, and 225 kg N ha-1 respectively, and potassium (0, 75, and 150 kg K2O ha-1) and cultivar (‘Ningmai 9’ and ‘Yangmai 10’) were the split plots. The results showed that SPAD and photosynthetic parameters (Pn, Fv /Fm, Fv /Fo, Fv’/Fm’, and ΦPSⅡ) were increased with N and K supply, compared with CK (no N and K fertilization). Compared with potassium fertilization, the role of nitrogen on SPAD and photosynthetic parameters (Pn, Fv /Fm, Fv /Fo, Fv’/Fm’, and ΦPSⅡ) was greater. The relationships between chlorophyll fluorescence parameters (Fv /Fm, Fv /Fo, Fv’/Fm’, and ΦPSⅡ) and Pn were all significant (P < 0.01). Photosynthetic parameters except SPAD were higher in ‘Yangmai 10’ than in ‘Ningmai 9’. The results suggested that higher chlorophyll fluorescence parameters (Fv /Fm, Fv /Fo, Fv’/Fm’ and ΦPSⅡ) affected by reasonable leaf N/K ratio at anthesis were the key physiological basis not only for higher Pn after anthesis, but also for getting almost the same yield of ‘Yangmai 10’ which needs more energy compared with that in ‘Ningmai 9’.
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