摘要:高温是影响棉花产量的重要环境因子，研究盛花期短期高温胁迫对海岛棉不同部位果枝产量及产量构成因素的影响，有助于为海岛棉选育耐热稳产性品种、制定丰产抗逆栽培技术提供理论方法。以‘新海43号’和‘新海49号’为材料，于盛花期在田间搭设增温棚，设置不同增温持续时间[0 d（CK）、3 d（H3）、6 d（H6）、9 d（H9）]模拟短期高温胁迫对海岛棉干物质积累、叶片净光合速率、蕾铃脱落率、产量及产量构成因素的影响。结果表明：盛花期短期高温胁迫，导致‘新海43号’和‘新海49号’中部果枝蕾铃脱落率显著增加，棉株总干物质积累量下降。在花后30~50 d，各增温处理棉铃的干物质量与对照相比显著降低；而花后40~50 d，两品种H6、H9处理茎、叶干物质量与对照相比显著升高。随生育进程的推进，‘新海43号’和‘新海49号’在H3、H6、H9处理下棉铃最大干物质量比对照分别降低8.9%、29.3%、36.3%和11.8%、28.1%、42.6%；棉铃日均积累量分别下降10.9%、32.8%、42.2%和12.8%、30.3%、45.9%；而达到快速积累期终止时期所需的时间分别增加5 d、8 d、14 d和1 d、5 d、10 d。在增温处理期间，两品种主茎叶Pn随增温持续时间的延长呈大幅下降趋势；增温结束后，各处理叶片Pn的衰减速度不同，在生殖生长后期（花后40 d）H3、H6、H9处理下叶片Pn均高于对照，表现为H9 > H6 > H3 > CK。短期高温胁迫导致两品种单株结铃数、单铃重和衣分显著降低，其中单株结铃数变异系数（15.4%~18.5%）最大，衣分变异系数（4.1%~4.7%）最小。‘新海43号’和‘新海49号’H3、H6、H9处理下单株结铃数分别减少21.6%、22.5%、28.9%和16.6%、26.4%、34.7%；而增温显著增加了上部果枝铃数，进而提高了上部果枝产量及产量贡献率。品种间，‘新海49号’净光合速率、单株结铃数和单铃重下降幅度以及蕾铃脱落率的增加幅度均大于‘新海43号’，说明‘新海43号’具有更好的耐热性。
关键词:海岛棉/
高温胁迫/
果枝位置/
干物质积累/
净光合速率/
产量
Abstract:High temperature is an important environmental factor affecting cotton yield. An experiment was conducted on the effects of short-term heat stress during the full bloom stage on fruit branch yield and yield components of island cotton; it is helpful to provide theoretical methods for breeding heat-resistant and stable-yielding varieties and formulating high-yield and stress-resistant cultivation techniques for island cotton. Using 'Xinhai 43' and 'Xinhai 49', a warming shed was set up in the field during the full bloom stage, and treatments of four warming levels[lasting for 0 (control), 3 (H3), 6 (H6), and 9 d (H9)] were employed to simulate the effects of short-term high temperature stress. The effects of temperature increase on dry matter accumulation, net photosynthetic rate, abscission rate of squares and bolls, yield, and yield components were analyzed. The results showed that short-term heat stress at the full bloom stage resulted in a significant increase in abscission rate of squares and bolls of the middle fruit branch of 'Xinhai 43' and 'Xinhai 49', and total dry matter accumulation of cotton plants decreased. At 30-50 days after anthesis, the dry matter of cotton bolls was significantly lower than that of the control. However, at 40-50 days after anthesis, the dry matter of the stems and leaves of two varieties with H6 and H9 treatments were significantly greater than those of the control. As the growth process progressed, compared with the control, the maximum dry matter of 'Xinhai 43' and 'Xinhai 49' with H3, H6 and H9 treatments decreased by 8.9%, 29.3% and 36.3%, and 11.8%, 28.1%, and 42.6%, respectively; and the daily average accumulation of cotton bolls decreased by 10.9%, 32.8%, and 42.2%, and 12.8%, 30.3%, and 45.9%, respectively. The time needed to reach the terminating date of fleet accumulation period increased by 5, 8, and 14 d, and 1, 5, and 10 d in 'Xinhai 43' and 'Xinhai 49', respectively. During the warming treatment, the Pn of the two varieties leaves decreased significantly with longer warming duration. After the end of warming, the senescence rate of Pn in each treatment was different. At the later stage of reproductive growth (40 days after anthesis), the Pn of leaves treated with H3, H6, and H9 was higher than those of the control, and in the order of H9 > H6 > H3 > CK. Short-term high temperature resulted in a significant decrease in boll number per plant, boll weight, and lint percentage. Among them, the coefficient of variation of boll number per plant (15.4% to 18.5%) was the largest, and the coefficient of variation of lint percentage (4.1% to 4.7%) was the smallest. Under the treatments of H3, H6, and H9, the boll number per plant of 'Xinhai 43' and 'Xinhai 49' decreased by 21.6%, 22.5%, and 28.9% and 16.6%, 26.4%, and 34.7%, respectively. However, the warming significantly increased the number of bolls in the upper fruit branches, and the number of bolls in the upper fruit branches of 'Xinhai 43' and 'Xinhai 49' increased by 0-24.9% and 2.7%-58.2% compared with the control. This, in turn, increased the yield and yield contribution rate of the upper fruit branches. Among varieties, the decrease in Pn, boll number, boll weight, and abscission rate of squares and bolls of 'Xinhai 49' were greater than those of 'Xinhai 43', suggesting that 'Xinhai 43' has better heat resistance.
Key words:Island cotton/
Heat stress/
Fruiting branch position/
Dry matter accumulation/
Leaf net photosynthetic rate/
Yield
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