Coordination of the cotton source–sink relationship is important. Although some indicators have been used to reflect the source-sink relationship in cotton, few indicators can directly demonstrate the source–sink relationship from the perspective of the cotton population. This study aimed to determine one or several indicators that can be used to directly reflect the source–sink relationship of the cotton population. Three field experiments were conducted with a conventional cotton cultivar (‘Sikang1’) in 2018 and 2019. Experiment I consisted of six planting densities: 3.0 × 10, 3.3 × 10, 3.6 × 10, 3.9 × 10, 4.2 × 10, 4.5 × 10 plants·ha. Experiment Ⅱ was composed of two types of studies. One was made up of one control and two square removed treatments, including 10 and 20% of squares removed from the whole plant, with no square removed as the control. The other study consisted of one control and two leaf-cutting treatments, in which 25 and 50% of the leaf area were cut off from the whole plant. Lint yield was enhanced by 11.2–66.1% in 2018, and the boll number per leaf increased from 0.225 to 0.282 boll·leaf. The boll number per square meter of leaf area increased from 22.7 to 27.2 bolls·m leaf, and the boll dry weight per square meter of leaf area increased from 119.3 to 149.7 g·m leaf in 2018. The results for 2019 were similar to those for 2018. There was significant linear positive correlations between lint yield and the above three measurements of the boll/leaf ratio. Moreover, these three measurements of the boll/leaf ratio were significantly and linearly positively correlated with each other, indicating that the three boll/leaf ratio measurements were similar and represented the coordination of the source–sink relationship of cotton population. The boll/leaf ratio can be used as an index to reflect the source–sink relationship of the cotton population. A higher boll/leaf ratio is beneficial for the population’s photosynthetic production, carbohydrate inversion, and transportation of photosynthetic products to the boll, which is conducive to increasing the lint yield in cotton. The results suggest that the boll/leaf ratio can be used as a diagnostic index for the coordination of the source–sink relationship.

中文翻译：

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铃/叶比改善棉花结铃期的源库关系和皮棉产量

协调棉花源库关系非常重要。尽管已有一些指标可以反映棉花的源库关系，但很少有指标能够直接从棉花群体的角度展示源库关系。本研究旨在确定一个或多个可直接反映棉花种群源库关系的指标。 2018 年和 2019 年，对常规棉花品种“斯康 1”进行了 3 次田间试验。试验一包括 6 种种植密度：3.0 × 10、3.3 × 10、3.6 × 10、3.9 × 10、4.2 × 10、4.5 × 10株·公顷。实验二由两类研究组成。一种是由一个对照和两个去除方格处理组成，包括从全株去除方格的10%和20%，不去除方格作为对照。另一项研究包括一个对照和两次切叶处理，其中 25% 和 50% 的叶面积从整株植物上被切掉。 2018年皮棉产量提高11.2%~66.1%，单叶铃数由0.225个铃·叶增加到0.282个铃·叶。 2018年每平方米叶面积棉铃数由22.7个棉铃·米叶增加至27.2个棉铃·米叶，每平方米叶面积棉铃干重由119.3克·米叶增加至149.7克·米叶。2019年结果与2019年相似2018 年皮棉产量与上述三种棉铃/叶比测量值之间存在显着的线性正相关关系。此外，这三个棉铃/叶比测量值之间呈显着的线性正相关，表明三个棉铃/叶比测量值相似，代表了棉花种群源库关系的协调性。棉铃/叶比可以作为反映棉花种群源库关系的指标。较高的铃/叶比有利于群体的光合生产、碳水化合物转化以及光合产物向棉铃的运输，有利于提高棉花皮棉产量。研究结果表明，铃/叶比可以作为源库关系协调的诊断指标。