Modeling Maize Canopy Morphology in Response to Increased Plant Density.

Liang He,Jincai Li,Weiwei Sun,Xiang Chen,Liqi Han,Youhong Song,Yuanshan Ma

doi:10.3389/fpls.2020.533514

Abstract

Increased plant density markedly affects canopy morphophysiological activities and crop productivity. This study aims to model maize canopy final morphology under increased interplant competition by revising a functional–structural plant model, i.e., ADEL-Maize. A 2-year field experiment was conducted at Mengcheng, Anhui Province, China, in 2016 and 2018. A randomized complete block design of five plant densities (PDs), i.e., 4.5, 6, 7.5, 9, and 15 plants m–2, with three replications was applied using a hybrid, i.e., Zhengdan 958. Canopy morphology at different PDs was measured with destructive samplings when maize canopy was fully expanded. The relationship of changes of organ morphology in relation to increased plant density was analyzed based on 2016 data. The ADEL-Maize was first calibrated for the hybrid at 4.5 plants m–2 and then revised by introducing relationships identified from 2016 data, followed by independent validation with 2018 field data. A heatmap visualization was shown to clearly illustrate the effects of increased plant density on final morphology of laminae, sheaths, and internodes. The logarithmic + linear equations were found to fit changes for the organ size versus increased plant density for phytomers excluding ear position or linear equations for the phytomer at ear position based on 2016 field data. The revision was then further tested independently by having achieved satisfactory agreements between the simulations and observations in canopy size under different PDs with 2018 field data. In conclusion, this study has characterized the relationship between canopy morphology and increased interplant competition for use in the ADEL-Maize and realized the simulations of final size of laminae, sheaths, and internodes, as affected by increased plant density, laying a foundation to test an ideotype for maize withstanding high interplant competition.

Highlights

Greater crop productivity and grain quality are required to ensure current and future food security due to continuous expansion of a large population and climate change (Ray et al, 2013; Long et al, 2015)
Lamina width, sheath length, sheath width, internode length, and internode diameter at different phytomers from 6 to 18 under 4.5 plants m−2 were listed in the second column after phytomer rank (Figure 1)
Both lamina and sheath widths decreased in response to increased interplant competition while lengths of internodes increased and diameters of internodes were reduced in response to increased plant densities (PDs), consistent with Andrieu et al (2006) and Song et al (2016)

Summary

Introduction

Greater crop productivity and grain quality are required to ensure current and future food security due to continuous expansion of a large population and climate change (Ray et al, 2013; Long et al, 2015). In particular, has been due to the greater tolerance of increased plant density (PD) (Tokatlidis and Koutroubas, 2004; Ci et al, 2011) by altering canopy architecture with erect leaves at the top and flat leaves at the bottom (Zhu et al, 2012), made available by the efforts of plant breeders (Chen et al, 2016). It is a straightforward strategy to improve canopy photosynthetic capacity during the flowering stage when kernel set is being determined under high interplant competition (Ciampitti and Vyn, 2011; Long et al, 2015; Liu et al, 2017)

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Conclusion