甜瓜主茎叶不同叶位SPAD值空间分布与氮素营养诊断

Spatial distribution and nitrogen diagnosis of SPAD value for different leaves position on main stem of muskmelon

在设施栽培条件下,研究甜瓜关键生育期不同叶位SPAD值的变异特征及与叶片、植株氮素含量的相关性,探索提出基于SPAD仪诊断氮素营养最佳的测定叶位。结果表明,在各施氮水平下,不同叶位间叶片SPAD值存在一定差异,各叶位叶片SPAD值随施氮量的增加而增加。在适宜施氮(N 210 kg/hm^2)水平下,各生育期顶3叶和顶4叶SPAD值变异系数显著低于顶1叶和顶2叶,不同叶位叶片SPAD值与叶片、植株含氮量有较好的相关性,其中顶3叶与叶片、植株含氮量相关性最高。因此,用叶绿素SPAD仪诊断甜瓜氮素营养,顶3叶为较理想的指示叶或参照叶。

Under the condition of protecting cultivation,the relevance among variability of SPAD values at different leaf positions and the nitrogen content of leaves in melon critical growth period was studied,the best leaf position of N diagnosis for muskmelon which based on SPAD meter was explored. The results showed that in different nitrogen situation,leaf SPAD value at different leaf positions were different. Leaf SPAD value raised with increasing nitrogen fertilization in all leaf positions. Under the optimum level of nitrogen（ N 210 kg / hm^2）,the variation coefficient of top 3^rd leaf and top 4^th leaf SPAD value were significantly lower than those of the top 1^st and 2^nd leaf in each growth stage. Leaf SPAD value of different leaf position had good correlation with N content of leaf and plant. The top 3^rd leaf had the best correlation with leaf and plant nitrogen content. Consequently,when the nitrogen nutrition of muskmelon was diagnosed by SPAD chlorophyll meter,the ideal indicator leaf was top 3-（rd） leaf.