棉花上部叶片叶绿素SPAD值动态变化研究

为了探索利用叶绿素SPAD值在不同生育阶段进行棉花营养诊断的方法,以2个早熟品种（‘中棉所36’、‘中棉所50’）和2个中熟品种（‘中棉所41’、‘鲁棉28’）为对象,研究了棉花主茎倒一至倒四叶在全生育期的叶绿素SPAD值动态变化,并研究了氮、磷施用量对‘鲁棉28’蕾期、花期和吐絮期主茎功能叶的SPAD值影响。结果表明：2个早熟品种的棉花主茎叶全生育期SPAD值呈现倒一叶〈倒二叶〈倒三叶〈倒四叶的规律,2个中熟品种在盛铃期以前主茎4片叶SPAD值也呈现和早熟品种一样的规律,但盛铃期以后SPAD值叶序变化不规则。在吐絮前,棉花主茎倒四叶SPAD值可以作为棉株营养诊断的参考,早熟品种棉花主茎倒一叶或倒二叶吐絮前10天和吐絮后10天左右的SPAD差值大小可以作为棉株衰老程度的参考值,中熟品种棉花主茎倒三叶吐絮前15天和吐絮后15天左右的SPAD差值大小可以作为棉株衰老程度的参考值。本试验条件下,纯氮用量高于270kg/hm2,吐絮期主茎功能叶SPAD值与不施氮处理差异极显著,高氮处理利于主茎功能叶在吐絮期维持较高的SPAD值;纯P2O5用量在120kg/hm2即能使吐絮期主茎功能叶维持较高的SPAD值,增加磷肥用量SPAD值反而下降。

A Study on Dynamic Change of Chlorophyll SPAD Values of Upper Leaves in Main Stem of Cotton

The target of this study was to seek methods of nutrition diagnosis of cotton at different growth and development stages by chlorophyll SPAD values of upper leaves of cotton plant. The experiment was carried out to study the dynamic change of first leaf to forth leaf from top of cotton main stem during the whole growth period with two early cultivars （CCRI 36, CCRI 50） and two mid-maturing cultivars （CCRI 41, SCRC 28）, at the same time the impact of different nitrogen and phosphorus fertilizer rates on chlorophyll SPAD values of the main stem function leaves of SCRC 28 were studied. The results showed that chlorophyll SPAD values of the main stem leaves of two early cultivars had same rule during the whole period, chlorophyll SPAD values of first leaf from top were lower than those of second leaf from top, second leaf from top were lower than third leaf from top, third leaf from top were lower than forth leaf from top, the same rule appeared in two mid-maturing cultivars before full-boll stage, but the order of chlorophyll SPAD values of upper four leaves was irregular after full-boll stage. The chlorophyll SPAD values of forth main stem leaf from top could be looked upon as the reference value of nutrient diagnosis before boll opening stage, difference value of chlorophyll SPAD values of first or second main stem leaf from top of early cultivars between about 10 days before boll opening stage and 10 days after boll opening stage could be looked upon as the reference value of degree of aging of cotton plant,difference value of chlorophyll SPAD values of third main stem leaf from top of mid-maturing cultivars between about 15 days before boll opening stage and 15 days after boll opening stage could be looked upon as the reference value of degree of aging of cotton plant. In the experiment, the chlorophyll SPAD values of main stem functional leaves had significant difference between the treatment with amount of net nitrogen more than 270 kg/hm 2 and the treatment with no nitrogen, the treatment with much more nitrogen had much higher chlorophyll SPAD values of main stem functional leaves during boll opening stage. The treatment with amount of net phosphorus pentoxide at 120 kg/hm 2 had much higher chlorophyll SPAD values of main stem functional leaves during boll opening stage, on the contrary, when amount of net phosphorus pentoxide was more than 120 kg/hm 2 ,chlorophyll SPAD values declined.