Context or problem

Drought can substantially limit yield in cotton, and water loss in any crop is closely associated with plant growth, but studies addressing the effects of growth management on drought sensitivity are limited in cotton.

Objective

We tested the hypothesis that aggressive plant growth management would decrease cotton sensitivity to drought during flowering and boll development.

Methods

Cotton was grown at a field site near Tifton, GA during the 2021 and 2022 growing seasons. Treatments included mepiquat chloride (MC) strategies (aggressive and untreated) and two water availability treatments (well-watered and drought-stressed). At approximately 2 weeks after first flower, water was withheld from the drought-stressed treatment for a three-week period, and well-watered plots were kept irrigated using a regionally accepted water balance approach. Measurements throughout the season included heights, nodes, length of the fourth internode below the plant terminal, nodes above white flower (NAWF), and soil moisture. End-of-season measurements included lint yield, fiber quality, and yield component assessments.

Results

MC treatment significantly affected plant height, mainstem node number, 4th internode length, and cutout date. Soil moisture was significantly reduced during the drought stress period. Aggressive MC treated plots showed less drought-induced yield reduction than untreated in response to drought, but did not reach the same lint yield, boll density, or uniformity as well-watered, untreated plots. Aggressive MC treatment produced greater seed surface area, seed number boll^-1, and boll mass.

Conclusions

Aggressive MC management may prevent drought-induced yield reductions but penalize yield under well-watered conditions. Among the potential components driving yield, boll number per unit land area was the most important contributor.

Implications or significance

Our findings highlight the potential for aggressive MC management to mitigate drought risk, but future efforts should evaluate this possibility in a broader range of cultivars adapted for production in the southeastern United States and with the inclusion of a moderate MC treatment.

中文翻译：

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干旱前助壮素管理对棉花需水高峰期干旱敏感性的影响

上下文或问题

干旱会大大限制棉花的产量，任何作物的水分流失都与植物生长密切相关，但针对棉花生长管理对干旱敏感性影响的研究有限。

客观的

我们测试了积极的植物生长管理会降低棉花在开花和结铃发育过程中对干旱的敏感性的假设。

方法

在 2021 年和 2022 年的生长季节，棉花在佐治亚州蒂夫顿附近的田地种植。处理包括助壮素 (MC) 策略（激进的和未处理的）和两种可用水处理（充分浇水和干旱胁迫）。在第一朵花后大约 2 周，干旱胁迫处理停止供水 3 周，并使用区域认可的水平衡方法灌溉水分充足的地块。整个季节的测量包括高度、节点、植物末端下方第四个节间的长度、白花上方的节点 (NAWF) 和土壤水分。季末测量包括皮棉产量、纤维质量和产量组成部分评估。

结果

MC处理显着影响株高、主干节数、第4节间长度和扦插日期。在干旱胁迫期间，土壤水分显着减少。积极的 MC 处理的地块显示干旱引起的减产比未处理的干旱少，但没有达到与水分充足、未处理的地块相同的皮棉产量、铃密度或均匀性。积极的 MC 处理产生更大的种子表面积、种子数铃^-1和铃质量。

结论

积极的 MC 管理可以防止干旱引起的减产，但会在水分充足的条件下减产。在驱动产量的潜在因素中，单位土地面积的铃数是最重要的贡献者。

影响或意义

我们的研究结果强调了积极的 MC 管理减轻干旱风险的潜力，但未来的努力应该在更广泛的适合美国东南部生产的品种中评估这种可能性，并包括适度的 MC 处理。