棉花叶色变化是棉田氮素供给能力和植株生育状况在外部形态上的综合反映,因此叶色也是看苗诊断的重要内容。棉花高产规律早有“二黑二黄”和“三黑三黄”的报导。现就以下三个问题谈我们的看法: 一、“二黑二黄”与“三黑三黄”“二黑二黄”认为苗期要黑,蕾花期要黄,铃期要黑,吐絮以后要黄。而“三黑三黄”认为盛蕾到初花还有一个黑的变化过程。盛蕾到初花有无黑黄变化是两种观点分歧所 Cotton leaf color change is cotton field nitrogen supply capacity and plant fertility in the external morphology of a comprehensive reflection of leaf color is also an important part of seedling diagnosis. The law of high yield of cotton has long been reported as “two black and two yellow” and “three black and three yellow”. Now on the following three questions about our views: First, the “two black two yellow” and “three black three yellow” “two black two yellow” that the seedling to black, yellow flower buds, bell to black, after bolting To yellow. The “three black and three yellow” that Shenglei to flower there is a black process of change. Shenglei to the beginning of flowers there is no change in black and yellow are two different views