化学调控对不同施氮量棉花冠层结构及产量的影响

为研究缩节胺对不同施氮量棉田的调控作用,以新陆中88号为材料,采用双因素裂区试验设计,设置320（N₃₂₀）和480 kg·hm^-2（N₄₈₀）2个纯氮水平和67.0（H1）、150.0（H2）、260.5（H3）、371.0 g·hm^-2 （H4）4个缩节胺剂量水平,研究不同处理下机采棉的株高日增量、株型、叶面积、比叶重及产量的变化。结果表明,各处理的冠层株型指标无显著差异,叶面积指数表现为随施氮量增多而增大;上部主茎节间长度、中上部果枝长度随缩节胺剂量增多而降低。N₃₂₀水平下棉花叶片SPAD值和散射辐射透过系数（TC）较高;且在H3处理下,主茎叶片比叶重、单株结铃数及单铃重最大,施氮量和缩节胺用量对籽棉产量存在互作效应。综上,施氮量增多使棉花徒长,中期通风透光差;缩节胺剂量增多对棉花株型有明显抑制效果,但会降低单株结铃数与单铃重。因此,施氮量和缩节胺用量分别为320.0 kg·hm^-2和260.5 g·hm^-2时有利于塑造良好株型,既可以保持棉花后期较高的叶面积指数,又可使田间中期保持良好的通风透光性,增加单株结铃数与单铃重,进而提高产量。

Effect of Chemical Regulation on Canopy Structure and Yield of Cotton with Different Nitrogen Amounts

In order to study the regulating effect of DPC on cotton fields with different nitrogen application rates, Xinluzhong 88 was as the material, and a two-factor split zone test design was adopted. 2 pure nitrogen levels were set including 320 （N₃₂₀） and 480 kg·hm^-2（N₄₈₀）, and 4 DPC doses were set including 67 （H1）, 150 （H2）, 260.5 （H3）, 371 g·hm^-2 （H4）. The plant height, plant type, leaf area, specific leaf weight and yield of machine-picked cotton under different treatments were determined. The results showed that there was no significant difference on the canopy index among different treatments. The leaf area index increased with the increase of nitrogen application, the internode length of the upper main stem and the length of the middle and upper fruit branches decreased with the increase of DPC dose. N₃₂₀ treatment had higher SPAD value and scattered radiation transmission coefficient （TC） . Under the H3 dosage, the specific leaf weight of the main stem, number of bolls per plant and weight of single boll were the largest, the yield of seed cotton was significant influenced by the interactive between nitrogen and DPC application. In summary,the increase of nitrogen application would make the cotton excessive growth, which resulted in the poor ventilation in medium stage of cotton growth. The increase in the DPC dose had an obvious inhibitory effect on the cotton plant type, which reduced the number of bolls per plant and weight of the boll. So, the recommended amounts of nitrogen and DPC were 320.0 kg·hm^-2 and 260.5 g·hm^-2, respectively, which should maintain the high leaf area index in the later stage, the good ventilation of field, the more number of bolls per plant and the weight of single boll, and the high yield of seed cotton.