Planting Density Induced Changes in Cotton Biomass Yield, Fiber Quality, and Phosphorus Distribution under Beta Growth Model

Aziz Khan,Xiangjun Kong,Daniel Kean Yuen Tan,Ruiyang Zhou,Ullah Najeeb,Kashif Akhtar,Jie Zheng,Fazal Munsif

doi:10.3390/agronomy9090500

Abstract

High input costs combined with multiple management and material inputs have threatened cotton productivity. We hypothesize that this problem can be addressed by a single fertilization at flowering with late sowing in a moderately populated plant stand. Field experiments were conducted to evaluate the cotton biomass accumulation, phosphorus dynamics, and fiber quality under three planting densities (low, 3 × 104; moderate, 6 × 104; and dense, 9 × 104 ha−1) and two cultivars (Zhongmian-16 and J-4B). High planting density had 6.2 and 12.6% larger stems and fruiting nodes m−2, while low density produced a 37.5 and 59.4% maximum height node ratio. Moderate density produced 26.4–15.5%, 24.7–12.6%, and 10.5–13.6% higher biomass accumulation rate at the peak bloom, boll set, and plant removal stages over low and high density in both years, respectively. J-4B produced a higher reproductive organs biomass yield when compared with Zhongmian-16 in both years. This higher biomass formation was due to both the higher average (0.8 VT kg·ha−1·d−1) and maximum (1.0 VM kg·ha−1·d−1) reproductive organ phosphorus uptake, respectively. Plants with low density had 5.3–18.5%, 9.5–15%, and 7.8–12.8% greater length, strength, and micronaire values over moderate and dense plants, respectively. Conclusively, moderate density with J-4B is a promising option for improved biomass, phosphorus acquisition, and fiber quality under a short season.

Highlights

An expanding population requires global efforts to increase crop production, especially those fulfilling food and clothing needs
This study aimed to explore how growth and how growth and nutrient influence biomass partitioning and fiber quality at nutrient dynamics influencedynamics biomass partitioning and fiber quality at critical reproductive criticalin reproductive cotton planting crops under varying planting density
Cotton plant height, fruiting nodes numbers m−2, and height to node ratio were significantly affected by density, cultivar, and year (p < 0.05)

Summary

Introduction

An expanding population requires global efforts to increase crop production, especially those fulfilling food and clothing needs. The recommended planting densities in China are 22.7 plants m−2 in the northwest [1], 5.3–7.5 plant m−2 in the Yellow River Valley [2], 36 plants m−2 in Xinjiang [3], and 3–9 plants m−2 in the Yangtze River Valley [4,5] Management strategies such as the application of mepiquat chloride [5], Agronomy 2019, 9, 500; doi:10.3390/agronomy9090500 www.mdpi.com/journal/agronomy. During later growth phases, an increase in the assimilate transport to the reproductive structures ensures better crop yield. An over-investment of the assimilate into the vegetative or reproductive organs in cotton plants could stimulate the abscission of leaves or fruits, respectively [10,11]. The aboveground biomass of a cotton plant at maturity is often less than the total biomass produced as the plant may shed old leaves and young fruits [8]

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