How does structure matter? Comparison of canopy photosynthesis using one- and three-dimensional light models: a case study using greenhouse cucumber canopies

Abstract

One-dimensional light models using the Beer-Lambert equation (BL) with the light extinction coefficient k are simple and robust tools for estimating light interception of homogeneous canopies. Functional-structural plant models (FSPMs) are powerful to capture light-plant interactions in heterogeneous canopies, but they are also more complex due to explicit descriptions of three-dimensional plant architecture and light models. For choosing an appropriate modelling approach, the trade-offs between simplicity and accuracy need to be considered when canopies with spatial heterogeneity are concerned. We compared two light modelling approaches, one following BL and another using ray tracing (RT), based on a framework of a dynamic FSPM of greenhouse cucumber. Resolutions of hourly-step (HS) and daily-step (DS) were applied to simulate light interception, leaf-level photosynthetic acclimation and plant-level dry matter production over growth periods of two to five weeks. Results showed that BL-HS was comparable to RT-HS in predicting shoot dry matter and photosynthetic parameters. The k used in the BL approach was simulated using an empirical relationship between k and leaf area index established with the assistance of RT, which showed variation up to 0.2 in k depending on canopy geometry under the same plant density. When a constant k value was used instead, a difference of 0.2 in k resulted in up to 27% loss in accuracy for shoot dry matter. These results suggested that, with the assistance of RT in k estimation, the simple approach BL-HS provided efficient estimation for long-term processes.

Low Plant Density Improves Fruit Quality without Affecting Yield of Cucumber in Different Cultivation Periods in Greenhouse

“…Selecting a proper planting density can optimize light interception and increase crop water productivity [35]. The plants growing with a low density easily absorbed the section of light that penetrated into the middle and lower parts of the canopy, resulting in an enhanced photosynthetic rate for leaves related to the fruiting, which was more conducive to the accumulation of fruit dry matter [36].…”

Cultivo e teor proteico do espinafre-da-amazônia (Alternanthera sessilis (L.) R.Br. ex DC) em função dos espaçamentos e doses de nitrogênio

“…Cultivos em densidades menores, promovem maior absorção de luz, principalmente por apresentarem maior absorção nas partes baixas e média do dossel da planta, influenciando diretamente na maior taxa fotossintética, que acarreta em maior formação destes compostos no metabolismo primário e secundário, adicionando maior valor nutricional e defesa das plantas (ALBA et al, 2000;ADAMS-PHILLIPS et al, 2004;PAO et al, 2021).…”

Functional–Structural Plant Models Mission in Advancing Crop Science: Opportunities and Prospects

“…First of all, it is known that the major strength in FSPMs is the fine simulation of explicit plant morphogenesis, 3D architecture, and architectural development; nevertheless, the key functional parts in many FSPMs are, to some extent, based on or adopted from the physiological processes used in conventional crop models, in particular, in the beginning when to illustrate the role of FSPMs by integrating both the plant architecture and physiological functions (De Reffye et al, 2009 ), which is still widely used. For example, the estimation of canopy photosynthesis in many FSPMs is based on empirical light extinction within the canopy as a function of leaf area index (Vos et al, 2010 ; Pao et al, 2021 ) rather than mechanistic interaction of irradiance with individual leaves, though there are many studies available in investigating such interaction (Buck-Sorlin et al, 2011 ; Sarlikioti et al, 2011b ). In addition, modeling transfer of incident light energy to the chemical energy in the form of carbohydrate in leaves can be realized by mechanistically biochemical model of leaf photosynthesis (Farquhar et al, 1980 ; Wu et al, 2016 ).…”