不同施氮时期对陆地棉叶片光合特性及产量构成的影响

在已确定棉花施氮总量的基础上，2011年进一步进行了不同施氮时期对陆地棉叶片光合特性和产量构成因素的研究。研究结果表明：在播前施150 kg·hm^-2基肥和花铃期施150 kg·hm^-2追肥的N3处理功能叶片的SPAD值和净光合速率在花铃期以后均处于较高水平，而叶面积指数则表现为蕾期和花铃期各追施150 kg·hm^-2氮肥的N4处理自花铃期保持最高水平，其次为N3处理。N3处理抑制蕾铃的脱落，其蕾铃脱落率分别比N2、N4处理低48.98%和44.44%。各处理皮棉产量以N3处理最高，达1324.7 kg·hm^-2,比施肥各处理的平均产量高出14.9%。

Effects of nitrogen fertilization time on photosynthetic characteristics and yield components of land cotton

The effect of fertilization time on photosynthetic characteristics and yield components of land cotton in 2011 was studied in this paper, under the condition that the total annual nitrogen fertilizer usage was fixed. The results showed that: in N3 treatment, 150 kg·hm^-2 of nitrogen fertilizer was applied before planting as base fertilizer and at flower and boll stage as boost, the SPAD value and net photosynthetic rate were high after the flower and boll stage. In N4 treatment, 150 kg·hm^-2 of nitrogen fertilizer was applied at budding stage and the flower and boll stage. In N4 treatment, the tested cotton had highest leaf area index, followed by the N3 treatment. N3 treatment also inhibited the abscission of the bud and boll of cotton. The bud a nd boll abscission rate in N3 treatment was 48.98% and 44.44% lower than in N2 and N4 treatment respectively. The N3 treatment achieved the highest Lint Yield and reached the maximum of 1 324.7 kg·hm^-2, which was 14.9% higher than the average lint yield of tested cottons in all treatments.