棉 花 学 报      Cotton Science    2009，21(3)：224-229

Effects of Nitrogen Application Rates and DPC Sparing Doses on Content of Chlorophyll and SPAD Value in Leaf of Cotton( Gossypium hirsutum L.)
MA Zong-bin¹，FANG Wei-ping²，XIE De-yi²，LI Ling-li¹，ZHU Wei¹
(1.College of Agriculture，Henan Agricultural University，Zhengzhou，Henan 450002，China；2.Economic Crop Research Institute，Henan Academy of Agricultural Sciences，Zhengzhou，Henan 450002，China)

Abstract：Effects of nitrogen application rates and mepiquat chloride（DPC）sparing doses on content of chlorophyll and SPAD value in leaf of earlier-middle spring cotton variety Yuza 35 and short-season one Yinshan 1 were studied.The results showed that content of chlorophyll and SPAD value in leaf of two cotton varieties increased with enhancing nitrogen application rates or DPC sparing doses.There were significantly positive correlations between SPAD value and content of chlorophyll in leaf in most growth stages.But content of chlorophyll in leaf decreased more quickly than SPAD value in later growth stage,i.e.,the content of chlorophyll in leaf in boll opening stage decreased significantly than that in full bolling stage, and the SPAD value in boll opening stage decrease slightly than that in full bolling stage.Therefore,SPAD value is still efficient to conduct leaf color threshold when DPC is applied to cotton,but attention should be paid to the different tendency of content of chlorophyll and SPAD value in later growth stage of cotton.
Key words：cotton；nitrogen application rates；mepiquat chloride；content of
chlorophyll；SPAD value       [Full Text, 2609KB]