| To address the effect of high temperature stress on cotton growth and development, a controlled high temperature treatment experiment was conducted to explore the effects of different high temperature conditions at various growth stages on leaf and boll abscission, net photosynthetic rate of leaves, boll formation rate, spatial distribution of fruiting branches, yield components, and fiber quality. The results showed that exposure to high temperatures caused abnormal shedding of leaves and bolls. As temperature increased and the duration of exposure lengthened, the abscission rates of leaves and bolls rose significantly. Compared with the control, the leaf and boll abscission rates increased by 50.7% and 33.7%, respectively, under 35℃ for 9 days, and by 52.3% and 37.5% under 38℃ for 9 days. The net photosynthetic rate of the leaves decreased significantly. However, as cotton continued to grow and develop, partial recovery of leaf function was observed. Prolonged heat stress also caused the zone with the highest boll setting rate to shift closer to the top of the plant. Moreover, heat stress significantly reduced both cotton yield and fiber quality. After 9 days of high temperature treatment, seed cotton yield decreased by 36.2%, the average fiber length and uniformity dropped by 4.50% and 0.65%, respectively, while the specific breaking strength and micronaire value increased by 1.49% and 2.22%. In conclusion, high temperatures during the flowering and bolling stages of cotton result in excessive leaf and boll abscission, reduce fiber quality, and yield loss. These findings provide a scientific basis for developing strategies to mitigate the effects of high temperature stress in cotton production. |
