Ultra-narrow row (UNR) cotton, a production system with rows spaced less than 40 cm apart, has been proposed as a system for earlier maturity without substantial yield loss. However, trials in the U.S.A. and Australia have found maturity benefits difficult to achieve consistently. Studies undertaken in high input cotton systems that compared UNR to conventionally (1 m) spaced cotton found yield differences but failed to demonstrate differences in crop maturity. This paper examines crop development and fruiting dynamics of the two systems in more detail to understand why there were no differences in maturity. Results showed that lack of difference in maturity between the row spacings was not influenced by differences in the time to reach crop development stages nor by lower fruit retention of early bolls in the UNR plants. Node production and fruiting site production on a per plant basis were significantly slower in the UNR plants from early in the growing season. Slower node and fruiting site production delayed maturity in the UNR plants as they set fewer fruit within the same period of time compared to plants grown in conventional spaced rows. The number of fruiting sites produced per plant was highly dependent on the amount of dry matter per plant. Fruiting site production was reduced in the UNR crop because each plant produced less total dry matter, and hence plant development was slower. To further help understand the reasons for outcomes generated in these studies, and how UNR could possibly mature earlier without impacting yield, a conceptual modelling framework was developed to integrate seasonal patterns in fruiting site production, retention, and boll growth. A key component of this framework is translating from a per plant basis to an area basis. The analysis showed that for individual UNR plants to mature earlier and maintain yield on an area basis, early node production and fruiting site production must proceed at a similar rate to conventionally spaced crops. In this scenario 90 % of final yield would be present 14 days earlier in the UNR crop compared to conventionally spaced crops. To realise any benefits of potential earlier maturity further research is needed to explore genetic or management interventions that might avoid the early competitive stress response that slows node development in UNR.

中文翻译：

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作物发育和保果率对超窄行棉作物成熟时间的影响


超窄行 （UNR） 棉是一种行间距小于 40 厘米的生产系统，已被提议作为一种早熟系统，而不会造成大量产量损失。然而，美国和澳大利亚的试验发现，很难始终如一地实现成熟度收益。在高投入棉花系统中进行的研究将 UNR 与传统 （1 m） 间隔棉花进行比较，发现产量存在差异，但未能证明作物成熟度的差异。本文更详细地研究了这两个系统的作物发育和结果动态，以了解为什么成熟度没有差异。结果表明，行距之间成熟度没有差异，既不受达到作物发育阶段时间差异的影响，也不受 UNR 植株早期棉铃保果率较低的影响。从生长季节的早期开始，UNR 植物的节点生产和每株果点生产明显缓慢。较慢的节点和结果位点生产延迟了 UNR 植物的成熟，因为与在常规间隔行中生长的植物相比，它们在同一时间段内结实的果实较少。每株植物产生的结果点数量在很大程度上取决于每株植物的干物质量。UNR 作物的果地产量减少，因为每株植物产生的总干物质较少，因此植物发育较慢。为了进一步帮助理解这些研究中产生结果的原因，以及 UNR 如何在不影响产量的情况下提前成熟，开发了一个概念建模框架，以整合果点生产、保留和棉铃生长中的季节性模式。该框架的一个关键组成部分是从每株植物转换为以面积为基础。 分析表明，为了使单个 UNR 植物更早成熟并保持面积产量，早期节点生产和结果点生产必须以与传统间隔作物相似的速度进行。在这种情况下，与传统间隔作物相比，UNR 作物将提前 14 天出现 90% 的最终产量。为了实现潜在的早熟的任何好处，需要进一步研究来探索遗传或管理干预措施，这些干预措施可能会避免减缓 UNR 淋巴结发育的早期竞争性应激反应。