Journal
BIOSYSTEMS ENGINEERING
Volume 204, Issue -, Pages 294-303Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.biosystemseng.2021.01.016
Keywords
Oryza sativa (L.); Canopy transpiration; Thermal imaging; Heat balance model; Aerodynamic resistance
Funding
- Japan Science and Technology Agency, PRESTO [JPMJPR16Q5]
- Japan Science and Technology Agency, KAKENHI [17H03755, JP19H02939, 20H02968]
- Grants-in-Aid for Scientific Research [17H03755, 20H02968] Funding Source: KAKEN
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The study modified the conventional heat balance model by measuring aerodynamic resistance in rice to improve stability under low wind speeds. Evaluating seven rice genotypes revealed that high-yielding cultivars consistently showed greater transpiration rates under various weather conditions.
An estimation of canopy photosynthetic activities is needed in order to better understand biomass production of field crops. Thermal imaging techniques and the heat balance model enable us to estimate canopy diffusive conductance (g(c)) and canopy transpiration rate (E) of crops under field conditions. However, because conventional methods are unstable when wind velocity is very low, it is difficult to apply this model directly to field-grown crops. In this study, we modified the conventional model by measuring aerodynamic resistance in rice (Oryza sativa (L.)) under windless conditions (r(a)*). The r(a)* ranged from 9.50 to 35.40 s m(-1) among the genotypes. By introducing the concept of r(a)* to the original heat balance model, the stability when wind velocity is under 3.0 m s(-1) improved greatly. Using seven rice genotypes, we evaluated genotypic differences in E with higher temporal resolution. The daily cumulative transpiration ranged from 2.32 kgm(-2) d(-1) to 10.29 kg m(-2) d(-1) depending on genotype and weather conditions. High-yielding cultivars consistently showed greater transpiration rates under various weather conditions. We confirmed the relationship between estimated E and final grain yield, especially during the daytime. Our modified model is useful as a monitoring tool for rice canopy transpiration. (C) 2021 IAgrE. Published by Elsevier Ltd. All rights reserved.
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