Abstract Mulched drip irrigation is a common water-saving irrigation technology that can improve water resource utilization efficiency in arid areas. The change of irrigation method affects the growth of crop root system and then regulates the growth of aboveground organs. However, there have been limited comparative studies on how mulched drip irrigation affects the cotton root growth and regulates the relationship between cotton root and shoot. The objective of this study was to determine whether mulched drip irrigation could achieve water-saving and high-yield cotton cultivation by regulating the growth redundancy of root and shoot. Under field conditions, mulched drip irrigation (conventional drip irrigation and excessive drip irrigation) and traditional flood irrigation (conventional flood irrigation and reduced flood irrigation) were used in this experiment. Traditional flood irrigation was used as the control group. The results showed that compared with the traditional flood irrigation, the higher soil water content under mulched drip irrigation increased the specific root length (SRL), which promoted the growth of fine root length and biomass at the full flowering stage and prophase full boll stage. The growth of fine roots increased the root-shoot ratio (R/S) of mulched drip irrigation, and then inhibited the excessive vegetative growth of the aboveground parts. When entering the late full boll stage and boll opening stage, the fine root biomass and fine root mass fraction decreased rapidly under the mulched drip irrigation, resulting in a lower R/S. The smaller R/S of mulched drip irrigation facilitated the distribution of photosynthetic products to reproductive organs, which increased the boll number per plant by 7.30 %–25.10 %, thus increasing the boll loading of fine root system and seed cotton yield. However, compared with conventional drip irrigation, over irrigation led to excessive vegetative growth of cotton under excessive drip irrigation, which resulted in the decrease of boll opening rate and seed cotton yield by 8.71 %–17.19 % and 14.14 %–24.27 %, respectively. Moreover, the smaller R/S at the late growth stage enabled conventional drip irrigation to achieve the maximum water use efficiency (WUE). Therefore, mulched drip irrigation promoted the root growth of cotton and inhibited the vigorous vegetative growth of shoot before the prophase full boll stage, and then reduced the growth redundancy of root and increased the productive capacity of the fine root system after the prophase full boll stage, which increased boll number per plant and yield. However, only under the appropriate irrigation amount (390 mm), mulched drip irrigation can increase both yield and WUE, thus achieving the goal of water-saving and high-yield cultivation.

中文翻译：

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灌溉方式调节根冠生长冗余对棉花根系生长、根冠比及产量构成的影响

摘要 地膜滴灌是一种常见的节水灌溉技术，可提高干旱地区水资源的利用效率。灌溉方式的改变影响作物根系的生长，进而调节地上器官的生长。然而，关于覆盖滴灌如何影响棉花根系生长和调节棉花根系与地上部关系的比较研究还很有限。本研究的目的是确定地膜滴灌是否可以通过调节根和芽的生长冗余来实现节水高产棉花栽培。在田间条件下，本试验采用覆盖滴灌（常规滴灌和过度滴灌）和传统漫灌（常规漫灌和减漫灌）。以传统漫灌作为对照组。结果表明，与传统漫灌相比，覆膜滴灌较高的土壤含水量增加了比根长（SRL），促进了盛花期和前期全铃期细根长和生物量的生长。细根的生长提高了地膜滴灌根冠比(R/S)，进而抑制了地上部分的过度营养生长。进入全棉期后期和开棉期时，覆盖滴灌下细根生物量和细根质量分数迅速下降，导致R/S较低。覆膜滴灌较小的R/S有利于光合产物向生殖器官的分配，使单株铃数增加7.30%~25.10%，从而提高细根系的铃载量和籽棉产量。然而，与常规滴灌相比，过度灌溉导致棉花在过度滴灌下营养过度生长，导致吐絮率和籽棉产量分别下降8.71%~17.19%和14.14%~24.27%。此外，生长后期较小的 R/S 使常规滴灌能够实现最大的水分利用效率 (WUE)。所以，地膜滴灌在棉铃前期前促进了根系生长，抑制了地上部的旺盛营养生长，在全铃前期后减少了根系的生长冗余，提高了细根系的生产能力，增加单株铃数和产量。但只有在适当的灌溉量（390 mm）下，地膜滴灌才能同时提高产量和WUE，从而达到节水高产栽培的目的。