How do cotton light interception and carbohydrate partitioning respond to cropping systems including monoculture, intercropping with wheat, and direct-seeding after wheat?

Xiaoyu Zhi,Yabing Li,Yingchun Han,Yaping Lei,Xiaofei Li,Beifang Yang,Shiwu Xiong,Zhengyi Fan,Guoping Wang,Fangfang Xing,Zhanbiao Wang,Lu Feng,Wujun Ma

doi:10.1371/journal.pone.0217243

Xiaoyu Zhi, Yabing Li + Show 11 more

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https://doi.org/10.1371/journal.pone.0217243

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Abstract

Different cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum) planting patterns are widely applied in the Yellow River Valley of China, and crop yield mainly depends on light interception. However, little information is available on how cotton canopy light capturing and yield distribution are affected by planting patterns. Hence, field experiments were conducted in 2016 and 2017 to study the response of cotton canopy light interception, square and boll distribution, the leaf area index (LAI) and biomass accumulation to three planting patterns: a cotton monoculture (CM, planted on 15 May) system, a cotton/wheat relay intercropping (CWI, planted on 15 May) system, in which three rows of wheat rows were intercropped with one row of cotton, and a system in which cotton was directly seeded after wheat (CWD, planted on 15 June). The following results were obtained: 1) greater light capture capacity was observed for cotton plants in the CM and CWI compared with the CWD, and the light interception of the CM was 22.4% and 51.4% greater than that of the CWI and CWD, respectively, at 30 days after sowing (DAS) in 2016; 2) more bolls occurred at the first sympodial position (SP) than at other SPs for plants in the CM; 3) based on the LAI and biomass accumulation, the cotton growth rate was the greatest in CWD, followed by CM and CWI; and 4) the CM produced significantly greater yields than did the other two treatments because it yielded more bolls and greater boll weight. Information on the characteristics of cotton growth and development in response to different planting patterns would be helpful for understanding the response of cotton yields to planting patterns and would facilitate the improvement of cotton productivity.

Highlights

Cotton (Gossypium hirsutum L.) is grown worldwide as a major source of natural fiber [1]
More light was intercepted in the cotton was directly seeded after wheat (CWD) than in the cotton/wheat intercropping (CWI) in the early cotton growth stage, which was attributed to the shedding effects of the wheat rows
In 2016, the light interception in the cotton monoculture (CM) was 22.4% and 51.4% higher than that in the CWI and CWD, respectively, at 30 days after sowing (DAS) (Fig 2)

Summary

Introduction

Cotton (Gossypium hirsutum L.) is grown worldwide as a major source of natural fiber [1]. In China, cotton is grown on 5.2 million hectares, and the annual production is 6.67 million tons [2]. Different cotton-wheat (Triticum aestivum L.) double cropping systems are commonly implemented in various countries worldwide, especially in the Yellow River Valley of China [3]. Double cropping systems present several other beneficial attributes, such as high light interception [4], high productivity per unit area of land [5], efficient use of both water and nutrients, sequestration of organic carbon and nitrogen in the soil, and suppression of pests and diseases. Double cropping systems produce substantial increases in multiple crop indexes and reduce competition between grain and cotton for land in China. Cotton sown into mature wheat fields prior to or after wheat harvest improves the distribution of labor over time

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