• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.357-365
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• 2016

The effects of elevated atmospheric $CO_2$ on photosynthesis and growth of Chinese cabbage (Brassica campestris subsp. napus var. pekinensis) were investigated to predict productivity in highland cropping in an environment where $CO_2$ levels are increasing. Vegetative growth, based on fresh weight of the aerial part, and leaf characteristics (number, area, length, and width) of Chinese cabbage grown for 5 weeks, increased significantly under elevated $CO_2$ ($800{\mu}mol{\cdot}mol^{-1}$) compared to ambient $CO_2$ ($400{\mu}mol{\cdot}mol^{-1}$). The photosynthetic rate (A), stomatal conductance ($g_s$), and water use efficiency (WUE) increased, although the transpiration rate (E) decreased, under elevated atmospheric $CO_2$. The photosynthetic light-response parameters, the maximum photosynthetic rate ($A_{max}$) and apparent quantum yield (${\varphi}$), were higher at elevated $CO_2$ than at ambient $CO_2$, while the light compensation point ($Q_{comp}$) was lower at elevated $CO_2$. In particular, the maximum photosynthetic rate ($A_{max}$) was higher at elevated $CO_2$ by 2.2-fold than at ambient $CO_2$. However, the photosynthetic $CO_2$-response parameters such as light respiration rate ($R_p$), maximum Rubisco carboxylation efficiency ($V_{cmax}$), and $CO_2$ compensation point (CCP) were less responsive to elevated $CO_2$ relative to the light-response parameters. The photochemical efficiency parameters ($F_v/F_m$, $F_v/F_o$) of PSII were not significantly affected by elevated $CO_2$, suggesting that elevated atmospheric $CO_2$ will not reduce the photosynthetic efficiency of Chinese cabbage in highland cropping. The optimal temperature for photosynthesis shifted significantly by about $2^{\circ}C$ under elevated $CO_2$. Above the optimal temperature, the photosynthetic rate (A) decreased and the dark respiration rate ($R_d$) increased as the temperature increased. These findings indicate that future increases in $CO_2$ will favor the growth of Chinese cabbage on highland cropping, and its productivity will increase due to the increase in photosynthetic affinity for light rather than $CO_2$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.167-174
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• 2019

A process-oriented crop growth model can simulate the biophysical process of rice under diverse environmental and management conditions, which would make it more versatile than an empirical crop model. In the present study, we examined chronology and background of the development of the rice growth models in Korea, which would provide insights on the needs for improvement of the models. The rice crop growth models were introduced in Korea in the late 80s. Until 2000s, these crop models have been used to simulate the yield in a specific area in Korea. Since then, improvement of crop growth models has been made to take into account biological characteristics of rice growth and development in more detail. Still, the use of the crop growth models has been limited to the assessment of climate change impact on crop production. Efforts have been made to apply the crop growth model, e.g., the CERES-Rice model, to develop decision support system for crop management at a farm level. However, the decision support system based on a crop growth model was attractive to a small number of stakeholders most likely due to scarcity of on-site weather data and reliable parameter sets for cultivars grown in Korea. The wide use of the crop growth models would be facilitated by approaches to extend spatial availability of reliable weather data, which could be either measured on-site or estimates using spatial interpolation. New approaches for calibration of cultivar parameters for new cultivars would also help lower hurdles to crop growth models.