Abstract Growth and reproductive structure retention in cotton (Gossypium hirsutum) is dependent on light intensity, which is often irregular in tropical environments due to shading from cloudiness associated with the monsoon. The objective of this study was to evaluate the potential effects that cloudiness-induced reproductive organ abscission and compensatory responses might have on cotton growth, partitioning and conversion of radiation to biomass (radiation use efficiency RUE) as this was unknown for the monsoon tropics. Cotton cultivars representing different morphology were sown in field experiments at closely timed intervals during the early monsoon over 5 seasons to expose crops to varying amounts of cloud-related shading, creating a matrix of crop responses. In paper I, final boll number was strongly linked with lint yield, and boll retention on the early and late flowering sympodia and yield were correlated with the radiation environment during flowering. Grouping sowing time treatments that had a similar intra-canopy distribution of bolls at maturity provided a mechanism to compare yield recovery post boll loss and consider causal factors. Maximum crop biomass ranged from 1232−1933 g m−2. Lint yield was correlated with the fraction of total biomass present as bolls (P Differences in biomass partitioning between cultivars were minor. When cloud cover abated, extended concurrent vegetative and reproductive growth enabled yield recovery. Greater LAI was a consequence of compensatory processes following fruit loss. Faster development of LAI in response to the monsoon during early flowering could further shade lower canopy fruiting sites, exacerbating fruit abscission and impacting yield compensation. RUEg (glucose equivalent) of 2.35 & 2.63 g MJ−1 PAR was comparable with cotton grown in temperate environments but declined when lower canopy fruit abscission followed by extended concurrent growth altered the ratio of vegetative vs reproductive biomass partitioning. Cloudiness poses a dichotomy of challenges for crop management during the tropical monsoon season. After cloudiness-induced fruit loss, extended concurrent growth when the radiation environment improves must be encouraged to enable the initiation of new fruiting sites for yield recovery. However, expansionary canopy growth in response to cloud and fruit loss may exacerbate detrimental shading of the lower canopy and detract from later yield recovery. Therefore management tactics including the use of irrigation, nutrient and growth regulant inputs must achieve an appropriate balance between vegetative and reproductive components during compensatory growth.

中文翻译：

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热带季风季节的棉花生产。II – 对棉铃损失和补偿做出反应的生物量积累、分配和 RUE

摘要 棉花 (Gossypium hirsutum) 的生长和生殖结构保留取决于光照强度，由于与季风相关的阴天阴影，光照强度在热带环境中通常是不规则的。本研究的目的是评估混浊引起的生殖器官脱落和补偿反应可能对棉花生长、分配和辐射转化为生物量（辐射利用效率 RUE）的潜在影响，因为这在季风热带地区是未知的。在 5 个季节的早期季风期间，在田间试验中以紧密的时间间隔播种代表不同形态的棉花品种，使作物暴露在不同数量的与云相关的阴影中，从而形成作物反应矩阵。在论文 I 中，最终棉铃数与皮棉产量密切相关，早花和晚花花期的留铃率和产量与开花期的辐射环境有关。将成熟时棉铃在冠层内分布相似的播种时间分组处理提供了一种机制来比较棉铃丢失后的产量恢复并考虑因果因素。最大作物生物量范围为 1232-1933 gm-2。皮棉产量与作为棉铃存在的总生物量的比例相关（栽培品种之间生物量分配的 P 差异很小。当云量减少时，延长的同步营养和生殖生长使产量恢复。较大的 LAI 是果实损失后补偿过程的结果. 在早期开花期间响应季风的 LAI 的更快发展可以进一步遮蔽较低的树冠结果点，加剧落果，影响产量补偿。2.35 和 2.63 g MJ-1 PAR 的 RUEg（葡萄糖当量）与在温带环境中种植的棉花相当，但是当较低的冠层果实脱落随后延长的同时生长改变了营养与生殖生物量分配的比率时，RUEg（葡萄糖当量）会下降。在热带季风季节，多云给作物管理带来了两方面的挑战。在阴天导致落果后，必须鼓励在辐射环境改善时延长并发生长，以启动新的结果点以恢复产量。然而，响应云和水果损失的扩张性冠层生长可能会加剧下部冠层的有害阴影，并有损于以后的产量恢复。因此，管理策略包括灌溉的使用，