小麦叶绿素荧光参数叶位差异及其与植株氮含量的关系

Difference of Chlorophyll Fluorescence Parameters in Leaves at Different Posi-tions and Its Relationship with Nitrogen Content in Winter Wheat Plant

以中蛋白质含量小麦品种矮抗58和高蛋白质含量品种郑麦366为试验材料,2008—2010年连续2个生长季进行了施氮梯度下(0、90、180和270kghm2)的田间试验。在关键生育时期同步测定叶片荧光参数、叶和茎生物质量及氮含量,建立了基于叶位差的小麦植株氮含量荧光估算模型。结果表明,在小麦旺盛生长的拔节至孕穗期叶绿素荧光参数Fm、Fv、Fv/Fm和Fv/Fo与对应叶片氮含量的相关系数分别为0.557、0.601、0.619和0.633,均达极显著水平(P<0.01)。顶三叶间荧光参数差异较小,随施氮水平提高,顶部第4叶荧光参数与顶三叶间差异逐渐缩小,说明其对增施氮肥反应敏感。顶部第4叶与顶部第1叶间的荧光参数差异(LPD4-1)可较好拟合小麦拔节期植株氮含量变化,Fv/Fo和Fv/Fm方程决定系数R2分别为0.644(P<0.001)和0.651(P<0.001);顶部第4叶与顶部第2叶间的荧光参数差异(LPD4-2)方程拟合决定系数有所降低,分别为0.626(P<0.002)和0.592(P<0.005);而顶部第4叶与顶三叶之间的差异(LPD4-n)与小麦孕穗期植株氮含量间呈显著线性关系,其Fo、Fv和Fm方程决定系数分别为0.726(P<0.001)、0.791(P<0.001)和0.784(P<0.001)。独立数据检验结果表明,小麦拔节期对Fv/Fo和Fv/Fm的LPD4-1预测精度R2分别为0.844(P<0.001)和0.828(P<0.001),相对误差(RE)分别为13.0%和16.7%,而LPD4-2估算植株氮含量精度有所降低,R2分别为0.793(P<0.001)和0.813(P<0.001),RE分别为16.9%和18.4%。小麦孕穗期对Fv和Fm的LPD4-n预测方程的R2分别为0.831(P<0.001)和0.815(P<0.001),RE分别为13.2%和16.4%。比较而言,小麦拔节期Fv/Fo的LPD4-1和孕穗期Fv的LPD4-n可更好地用于评估不同条件下植株氮含量的变化,为施肥调控提供决策依据。

For diagnosing nitrogen （N） nutrient status in winter wheat plant based on fluorescence parameters of leaves, two cultivars with Aikang 58 （mid-protein content） and Zhengmai 366 （high-protein content） were used in experiments with N application rates of 0, 90, 180, and 270 kg ha^-1 in 201）8-2009 and 2009-2010 growing seasons. The fluorescence parameters were measured in the first, second, third, and fourth leaves from the top of plant from jointing to maturity stage. The N contents and biomasses of leaf and culm were determined through destructive sampling and chemical assay. The leaf N contents at different leaf positions were significantlycorrelated with flnorescence parameters from jointing to booting stage （P 〈 0.01）. The correlation coefficients of N content with Fm, Fv, Fv/Fm, and Fv/Fo were 0.557, 0.601, 0.619, and 0.633, respectively. The fluorescence pa- rameters of the top three leaves had small differences, which were much higher than those of the fourth leaf from the top. How- ever, the differences reduced gradually with the increase of N application rate. This indicated a sensitive response of leaf position to N application. The differences of Fv/Fo and Fv/Fm between the fourth and the first leaves （LPD4.0 were significantly correlated with N content in plant （PNC） at jointing stage （R2 = 0.644 for Fv/Fo and R2 = 0.651 for Fv/Fm）; whereas, the differences of Fv/Fo and Fv/Fm between the fourth and the second leaves （LPD4-2） had less accurate predictions with smaller R^2 values （R2 = 0.626 for Fv/Fo and R^2 = 0.592 for Fv/Fm）. At booting stage, linear equations were obtained for Fo, Fv, and Fm differences （LPD4-n） between the fourth and the top three leaves （R^2 = 0.726 for Fo, R^2 = 0.791 for Fv, and R2 = 0.784 for Fm）. Using independent datasets to predict PNC at jointing stage with the LPD4-1 and LPD4-2 equations based on Fv/Fo and Fv/Fm, the R2 values for LPD4-1 were 0.844 and 0.828 with relative errors of 13.0% and 16.7%, respectively; and the R^2 values for LPD4-2 were 0.793 and 0.813 with relative errors of 16.9% and 18.4%, respectively. The result showed that the estimations were reliable. At booting stage, the best predic- tion of PNC was from the LPD4-n equation based on Fv and Fro, and R^2 values were 0.831 and 0.815 with relative errors 13.2% and 16.4%, respectively. In conclusion, the LPD4-1 equation based on Fv/Fo at jointing stage and the LPD4-n model based on Fv at booting stage are applicable to estimate PNC of wheat.