Context or problem

The effect of nitrogen (N) application rate on lint yield and yield components have been studied extensively in cotton. However, reports quantifying contributions to N-induced yield loss and the response of intra-boll yield components to N deficiency are far less common.

Objectives

The objectives of this study were to 1) determine the effect of N application rate on lint yield biomass and fiber quality in cotton, 2) assess the contributions of intercepted photosynthetically active radiation (IPAR), radiation use efficiency (RUE), and harvest index (HI) to N-induced yield loss in cotton, and 3) characterize the effect of N application rate on yield component responses in cotton.

Methods

An experiment was conducted at a field site near Tifton, Georgia, USA during the 2021 and 2022 growing seasons. The experiment was arranged as a randomized complete block design with five replications and five nitrogen application rates (0, 44, 89, 134, and 179 kg N ha⁻¹). The studied parameters were lint yield, IPAR, RUE, HI, fiber quality, yield components, and yield loss contributions.

Results

Lint yield was significantly affected by N application rate, with yields ranging from 1452 to 1848 kg ha⁻¹. Similarly, total IPAR was 23% lower for the 0 kg N ha⁻¹ treatment than the 134 kg N ha⁻¹ treatment, and IPAR contributed significantly to yield loss, with a 427 kg ha⁻¹ loss attributable to IPAR under N deficiency. RUE was 37% higher for the 179 kg N ha⁻¹ treatment than the 0 kg N ha⁻¹ treatment and contributed positively to yield in the highest N rates (179 kg N ha⁻¹). However, yield improvements due to RUE were mitigated by low HI values in the highest N application rate. Boll density was the most strongly and positively associated yield component parameter with N-induced variability in lint yield, whereas lint percent and lint production per seed were negatively associated with lint yield.

Conclusions

Among the three physiological yield-driving parameters, light interception by the canopy was the primary contributor to N-induced yield loss. Boll density was the primary yield component governing N-induced variation in lint yield. Increased N application rate promotes greater dry matter partitioning to seeds than fiber, resulting in more seeds per boll and lower lint percent, lint weight per seed, and individual fiber weight.

Implications or significance

The results contained here identify the most important functional traits for determining lint yield response to N application rate.

中文翻译：

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量化田间棉花氮诱导产量变化的生理贡献

上下文或问题

已经在棉花中广泛研究了氮 (N) 施用率对皮棉产量和产量构成因素的影响。然而，量化对 N 诱导的产量损失的贡献以及棉铃内产量成分对 N 缺乏的反应的报告并不常见。

目标

本研究的目的是 1) 确定施氮量对棉花皮棉产量生物量和纤维质量的影响，2) 评估拦截的光合有效辐射 (IPAR)、辐射利用效率 (RUE) 和收获指数的贡献(HI) 对棉花中氮诱导的产量损失的影响，以及 3) 描述了施氮量对棉花产量构成反应的影响。

方法

在 2021 年和 2022 年的生长季节期间，在美国佐治亚州蒂夫顿附近的田间进行了一项实验。实验被安排为具有五次重复和五种施氮率（0、44、89、134 和 179 kg N ha ^-1）的随机完整区组设计。研究的参数是皮棉产量、IPAR、RUE、HI、纤维质量、产量组成部分和产量损失贡献。

结果

皮棉产量受施氮量的显着影响，产量范围为 1452 至 1848 kg ha ^-1。^{类似地，0 kg N ha -1}处理的总 IPAR 比 134 kg N ha ^-1处理低 23% ，并且 IPAR 对产量损失有显着影响，在缺氮情况下 IPAR 造成427 kg ha ^{-1损失。179 kg N ha -1}处理的 RUE 比 0 kg N ha ^-1处理高 37% ，并且在最高 N 施用量（179 kg N ha ^-1). 然而，由于 RUE 导致的产量提高被最高 N 施用率下的低 HI 值所抵消。棉铃密度是与氮诱导的皮棉产量变异性最密切和正相关的产量构成参数，而皮棉百分比和每粒种子的皮棉产量与皮棉产量呈负相关。

结论

在三个生理产量驱动参数中，冠层的光拦截是氮诱导的产量损失的主要原因。棉铃密度是控制 N 诱导的皮棉产量变化的主要产量因素。增加的 N 施用率促进更多的干物质分配给种子而不是纤维，导致每个铃更多的种子和更低的皮棉百分比、每个种子的皮棉重量和单个纤维重量。

影响或意义

此处包含的结果确定了决定皮棉产量对施氮量的响应的最重要的功能性状。