Study on Light Interception and Biomass Production of Different Cotton Cultivars.

Zhigang Bai,Lu Feng,Beifang Yang,Yaping Lei,Xiaoyu Zhi,Zhengyi Fan,Yingchun Han,Wenli Du,Shuchun Mao,Guoping Wang,Yabing Li,Tianzhen Zhang

doi:10.1371/journal.pone.0156335

Abstract

Identifying the characteristics of light interception and utilization is of great significance for improving the potential photosynthetic activity of plants. The present research investigates the differences in absorbing and converting photosynthetically active radiation (PAR) among various cotton cultivars. Field experiments were conducted in 2012, 2013 and 2014 in Anyang, Henan, China. Ten cultivars with different maturity and plant architectures were planted at a density of 60,000 plants ha-1 in randomized blocks, with three replicates. The spatial distribution of light in canopy was measured and quantified with a geo-statistical method, according to which the cumulative amount of intercepted radiation was calculated by Simpson 3/8 rules. Finally, light interception was analyzed in association with the biomass accumulation of different cultivars. The key results were: (1) late-maturing varieties with an incompact plant architecture captured more solar radiation throughout the whole growth period than middle varieties with columnar architecture and even more than early varieties with compact architecture, and they produced more biomass; (2) the highest PAR interception ratio and the maximum biomass accumulation rate occurred during the blossoming and boll-forming stage, when leaf area index (LAI) reached its peak; (3) the distribution within the canopy presented a significant spatial heterogeneity, and at late growing stage, the PAR was mainly intercepted by upper canopies in incompact-type plant communities, but was more homogeneous in columnar-type plants; however, the majority of radiation was transmitted through the canopy in compact-type colonies; (4) there was not a consistent variation relationship between the cumulative intercepted PAR (iPAR) and biomass among these cultivars over the three years of the study. Based on these results, we attempted to clarify the distinction in light spatial distribution within different canopies and the patterns of PAR interception in diverse cotton cultivars with different hereditary characters, thereby providing a significant basis for researchers to select cultivars with appropriate growth period and optimal plant architecture for improvement of light interception and utilization.

Highlights

Solar radiation provides a free energy source for plant growth [1], but only the photosynthetically active part of the spectrum (400–700 nm) can directly drive photosynthesis
We attempted to clarify the distinction in light spatial distribution within different canopies and the patterns of photosynthetically active radiation (PAR) interception in diverse cotton cultivars with different hereditary characters, thereby providing a significant basis for researchers to select cultivars with appropriate growth period and optimal plant architecture for improvement of light interception and utilization
Further studies indicate that the green leaf area, its duration of exposure, and the canopy structure mainly govern the first attribute of PAR interception; Radiation Use Efficiency (RUE) is largely controlled by plant’s net-photosynthetic capacity, as well as by canopy structure to some extent [5]

Summary

Introduction

Solar radiation provides a free energy source for plant growth [1], but only the photosynthetically active part of the spectrum (400–700 nm) can directly drive photosynthesis. It is defined as Photosynthetically Active Radiation (PAR) [1,2]. Louarn G. expressed that crop biomass production was attributed to the following two factors: amount of PAR intercepted by the canopy and efficiency of converting the captured radiation into biomass, i.e., Radiation Use Efficiency (RUE) [4]. To fully understand the underlying processes of radiation capture and energy fixation into biomass, it is crucial to deeply explore the detailed and precise characteristics of light distribution in the plant canopy [11].

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Conclusion