黄瓜叶片氮素诊断的最佳位点选择

Determination of Suitable Leaf Location for Nitrogen Diagnosis in Cucumber

在温室条件下测定并分析不同施氮水平下黄瓜正3叶叶片不同位点的SPAD值的空间分布特征,并对不同位点的SPAD值与叶片含氮量之间的相关性进行分析,探求应用SPAD计诊断黄瓜氮素营养状况的最佳测试位点。结果表明,黄瓜正3叶叶片不同位点的SPAD值存在显著的分布差异;比较不同位点的SPAD值的变异系数发现,叶片边缘的变异系数明显高于主叶脉两侧,而叶尖部三角区域的变异系数明显高于叶片其他任何区域;叶片各位点的SPAD值与叶片含氮量均存在明显的相关关系。初步研究选择离叶尖部的相对距离20%与叶边缘之间的叶尖顶三角区域作为黄瓜氮素诊断的最佳位点。

To determine the best leaf position for nitrogen diagnosis in cucumber with SPAD meter,greenhouse experiments were carried out to study spatial distribution of SPAD value of different position of the3 rd fully expanded cucumber leaf in the effect of different nitrogen levels,and the correlations between SPAD values and nitrogen concentration of chlorophyll. The results showed that there was remarkable different SPAD value in different positions of the 3rd fully expanded leaf. The coefficient of variation of leaf edge was significantly higher than that of the edge of the main vein,and the coefficient of variation of triangular area of leaf tip was significantly higher than that of any other leaf area through comparing the coefficients of SPAD value variation. There was a significant correlation between SPAD values and leaf nitrogen content. Preliminary study showed that triangular area from the 20% leaf tip to leaf edge was the best position for nitrogen diagnosis.