棉花功能叶不同位点SPAD值与氮素养分相关性

通过水培试验,设N0(0,不供氮)、N1.5(1.5mmol/L,适量供氮)、N15(15mmol/L,过量供氮)3个供氮处理,分4次测定棉花功能叶1～17个不同位点SPAD值和含氮量,分析棉花功能叶片不同位点SPAD值与植株氮素养分的相关关系。结果表明,随施氮量增加,棉花生长量也显著增加,N0、N1.5、N15处理的施氮量与棉花生长量、氮吸收量及叶片氮含量的相关性达到显著水平,相关系数分别为0.669 0、0.769 1和0.742 0,而棉花叶片平均SPAD值与施氮量、氮素吸收量相关性不显著,相关系数仅为0.241 8。可见,棉花地上部生物量随施氮量增加而显著增加,地上部的植株氮素水平与功能叶平均SPAD值相关性低,另外,选择适宜的观测位点十分必要,棉花功能叶中远离叶柄而靠近叶缘的位点适宜作为SPAD仪的测定区域。

Correlation Analysis between Nitrogen Nutrient and SPAD Values on Different Site of Functional Leaf in Cotton

To choose the suitable SPAD site on functional leaf for nitrogen nutrition diagnosis in cotton , the aquiculture test was conducted with three nitrogen treatments, including N₀ (0, not for nitrogen), N_1.5 (1.5 mmol/L, right amount for nitrogen), and N₁₅ (15 mmol/L, too much for nitrogen), and measured SPAD values and nitrogen content at 1-17 on cotton function leaf for four times to analyze the relationship between plant nitrogen nutrient and SPAD measured sites on functional leaf in cotton. The results showed that with the increase of nitrogen, cotton growth increased significantly, nitrogen applications of N₀, N_1.5, and N₁₅ treatment had high significant correlation with cotton growth, absorbance and content of nitrogen in leaf with the correlation coefficients of 0.669 0,0.769 1 and 0.742 0, respectively. But average SPAD values of cotton leaf had lower correlation coefficient (0.241 8) with application and uptake of nitrogen. In conclusion, the aboveground biomass of cotton increased significantly with nitrogen application, there were low correlation between nitrogen level in aboveground part of cotton plant and average SPAD value of function leaf, so choosing appropriate observation site was very necessary, and the suitable site for SPAD measurement located in leaf margin area far from petiole of cotton functional leaf.