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以北疆高产棉花为研究对象,对3种密度条件下不同打顶时间调控的高产棉花光合势、最大叶面积指数(LAImax)、冠层透光率、纤维品质和产量等进行了研究。在密度梯度上,随密度增加棉花产量增加。在225?03和300?03株穐a-1高密度条件下,与同密度下1次打顶(7月5日)相比,2次打顶增产8.4%和13.4%,3次打顶增产6.4%和7.1%。在150?03株穐a-1密度情况下,7月5日1次打顶处理产量最高,2次、3次打顶处理产量分别下降8.2%和6.2%。低密度情况下,棉田苗蕾期LAI较小、漏光损失大,光合势低,是实现高产、超高产的主要限制因子,分期打顶使群体适宜性降低,导致减产。高密度条件下棉花苗蕾期LAI增加,提高了棉花群体光合势;分期打顶使LAI在冠层中的分布向上向下“分异”,保证了较适宜的LAImax及其在冠层中的合理分布。当密度增加至300?03株穐a-1时,纤维比强度显著下降。生产上宜将最高密度(实际收获密度)设定在225?03株穐a-1左右,既能增强棉花群体的适应性,提高产量,且对品质影响不明显。
With high yielding cotton in northern Xinjiang as research object, photosynthetic potential, maximum leaf area index (LAImax), canopy light transmittance, fiber quality and yield of high yield cotton under different densities were studied under different densities. On the density gradient, cotton yield increases with increasing density. Compared with 1 topping at the same density (July 5), the yield of 2 topping increased by 8.4% and 13.4% at 225 03 03 and 300 03 03 穐 a-1 high density, Increased 6.4% and 7.1%. At the density of 150-3 plants, the yield was the highest on July 5, while the yield on the second and the third topping decreased by 8.2% and 6.2% respectively. Under low density, the LAI in cotton seedling stage is small, the light leakage loss is large and the photosynthetic potential is low, which is the main limiting factor to achieve high yield and super high yield. The staging topping reduces the population suitability and leads to the decrease of yield. Under high density, the LAI of cotton increased at the budding stage, which increased the photosynthetic potential of cotton population. The staging of the LAI in the canopy caused the LAI distribution in the canopy to “differentiate” from top to bottom, which ensured the more suitable LAImax and its LAImax Reasonable distribution. When the density increased to 300 穐 03 穐 a-1, the fiber specific strength decreased significantly. Production should be the highest density (actual harvest density) is set at about 225 03 03 strains 穐 a-1, both to enhance the adaptability of cotton populations and increase yield, and the quality of the impact is not obvious.