Sweet Pepper (Capsicum annuum L.) Canopy Photosynthesis Modeling Using 3D Plant Architecture and Light Ray-Tracing.

Jee Hoon Kim,Joon Woo Lee,Jong Hwa Shin,Jung Eek Son,Tae In Ahn,Kyung Sub Park

doi:10.3389/fpls.2016.01321

Jee Hoon Kim, Joon Woo Lee + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2016.01321

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Abstract

Canopy photosynthesis has typically been estimated using mathematical models that have the following assumptions: the light interception inside the canopy exponentially declines with the canopy depth, and the photosynthetic capacity is affected by light interception as a result of acclimation. However, in actual situations, light interception in the canopy is quite heterogenous depending on environmental factors such as the location, microclimate, leaf area index, and canopy architecture. It is important to apply these factors in an analysis. The objective of the current study is to estimate the canopy photosynthesis of paprika (Capsicum annuum L.) with an analysis of by simulating the intercepted irradiation of the canopy using a 3D ray-tracing and photosynthetic capacity in each layer. By inputting the structural data of an actual plant, the 3D architecture of paprika was reconstructed using graphic software (Houdini FX, FX, Canada). The light curves and A/Ci curve of each layer were measured to parameterize the Farquhar, von Caemmerer, and Berry (FvCB) model. The difference in photosynthetic capacity within the canopy was observed. With the intercepted irradiation data and photosynthetic parameters of each layer, the values of an entire plant's photosynthesis rate were estimated by integrating the calculated photosynthesis rate at each layer. The estimated photosynthesis rate of an entire plant showed good agreement with the measured plant using a closed chamber for validation. From the results, this method was considered as a reliable tool to predict canopy photosynthesis using light interception, and can be extended to analyze the canopy photosynthesis in actual greenhouse conditions.

Highlights

Canopy photosynthesis is one of the important factors for estimating crop growth and establishing the strategy of CO2 fertilization inside a greenhouse
Scaling up from leaf to canopy, intercepted radiation and the optical and physiological properties related to the photosynthetic capacity should be considered, including leaf age, leaf acclimation to light, and nitrogen distribution within the canopy
It is necessary to clarify the relationship between light acclimation and nitrogen distribution, which is heterogeneous within the canopy

Summary

Introduction

Canopy photosynthesis is one of the important factors for estimating crop growth and establishing the strategy of CO2 fertilization inside a greenhouse. Scaling up from the leaf to the canopy, the vertical pattern of the intercepted irradiation can be affected by the vertical structure of the whole plant and additional shading effects would occur from neighboring plants in the canopy (Caldwell et al, 1986; Chen et al, 1999) Other variances such as the direction of the sunlight, the ratio of the diffuse light, the greenhouse structure, the plant growth stage, and the plant density affect the intercepted irradiation inside the canopy (Elifis et al, 1989; Lieth and Pasian, 1990; Stirling et al, 1994; Buck-Sorlin et al, 2011). In estimating the canopy photosynthesis, it is important to investigate the light interception of the plant caused by these variances

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