• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.228-232
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• 2018

Process-based crop models have been used to assess the impact of climate change on crop production. These models are implemented in procedural or object oriented computer programming languages including FORTRAN, C++, Delphi, Java, which have a stiff learning curve. The requirement for a high level of computer programming is one of barriers for efforts to develop and improve crop models based on biophysical process. In this study, we attempted to develop a Chinese cabbage model using Microsoft Excel with Visual Basic for Application (VBA), which would be easy enough for most agricultural scientists to develop a simple model for crop growth simulation. Results from Soil-Plant-Atmosphere-Research (SPAR) experiments under six temperature conditions were used to determine parameters of the Chinese cabbage model. During a plant growing season in SPAR chambers, numbers of leaves, leaf areas, growth rate of plants were measured six times. Leaf photosynthesis was also measured using LI-6400 Potable Photosynthesis System. Farquhar, von Caemmerer, and Berry (FvCB) model was used to simulate a leaf-level photosynthesis process. A sun/shade model was used to scale up to canopy-level photosynthesis. An Excel add-in, which is a small VBA program to assist crop modeling, was used to implement a Chinese cabbage model under the environment of Excel organizing all of equations into a single set of crop model. The model was able to simulate hourly changes in photosynthesis, growth rate, and other physiological variables using meteorological input data. Estimates and measurements of dry weight obtained from six SPAR chambers were linearly related ($R^2=0.985$). This result indicated that the Excel/VBA can be widely used for many crop scientists to develop crop models.

• Horticultural Science & Technology
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• v.35 no.1
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• pp.1-10
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• 2017

We investigated growth, clove development, and photosystem II activity in garlic (Allium sativum L.) grown under different day/night temperature regimes using Soil-Plant-Atmosphere - Research (SPAR) chambers to determine the optimum cultivation temperature and to assess the impact of temperature stress on garlic. In the early stages of growth, plant growth increased markedly with temperature. At harvest time, however, the pseudostem diameter decreased significantly under a relatively low day/night temperature range ($14/10-17/12^{\circ}C$), suggesting that these temperature conditions favor regular bulb growth. At harvest time, the bulb diameter and height were great at $14/10-23/18^{\circ}C$, whereas the bulb fresh weight and number of cloves per bulb were greatest at $17/12-20/15^{\circ}C$. However, the number of regularly developed cloves per bulb was highest at the relatively low temperature range of $14/10-17/12^{\circ}C$, as were the clove length and fresh weight. The photochemical efficiency ($F_v/F_m$) and potential photochemical efficiency ($F_v/F_o$) of photosystem II in the leaves of garlic plants were higher at $14/10-20/15^{\circ}C$ and lower at temperatures below $14/10^{\circ}C$ or above $20/15^{\circ}C$, implying that the $14/10-20/15^{\circ}C$ temperature range is favorable, whereas temperatures outside this range are stressful for garlic growth. Furthermore, at temperatures above $20/15^{\circ}C$, secondary growth of garlic, defined as lateral bud differentiation into secondary plants, continuous growth of the cloves of the primary plants, or the growth of bulbil buds into secondary plants, was enhanced. Therefore, to achieve commercial production of fresh scapes and bulbs of garlic, it may be better to grow garlic at relatively low temperature ranges of $14/10-17/12^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.164-173
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• 2018

Elevated atmospheric carbon dioxide concentration ($CO_2$) is a major component of climate change, and this increase can be expected to continue into the crop and food security in the future. In this study, Soil-Plant-Atmosphere-Research (SPAR) chambers were used to examine the effect of elevated $CO_2$, temperature, and drought on the canopy architecture and concentration of macronutrients in potatoes (Solanum tuberosum L.). Drought stress treatments were imposed on potato plants 40 days after emergence. Under AT+2.8C700 (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$), at maximum leaf area, elevated $CO_2$, and no drought stress, a significant increase was observed in both the aboveground biomass and tuber, and for the developmental stage. Even though $CO_2$ and temperature had increased, AT+2.8C700DS (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$ under drought stress) under drought stress showed that the leaf area index (LAI) and dry weight were reduced by drought stress. At maturity, potatoes grown under $CO_2$ enrichment and no drought stress exhibited significantly lower concentrations of N and P in their leaves, and of N, P, and K in tubers under AT+2.8C700. In contrast, elevated $CO_2$ and drought stress tended to increase the tuber Mg concentration under AT+2.8C700DS. Plants grown in AT+2.8C700 had lower protein contents than plants grown under ATC450 (30-year average temperature at $400{\mu}mol\;mol^{-1}$ of $CO_2$). However, plants grown under AT+2.8C700 showed higher tuber bulking than those grown under AT+2.8C700DS. These findings suggest that the increase in $CO_2$ concentrations and drought events in the future are likely to decrease the macronutrients and protein concentrations in potatoes, which are important for the human diet.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.179-187
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• 2016

This study was conducted to determine the impact of elevated temperature and $CO_2$ concentration based on climate change scenario on growth and fruit quality of pepper (Capsicum annuum L. cv. Muhanjilju) with SPAR (Soil Plant Atmosphere Research) chamber. The intraday temperatures of climate normal years fixed by $20.8^{\circ}C$ during the growing season (May 1~October 30) of climatic normal years (1971~2000) in Andong region. There were treated with 4 groups such like a control group (ambient temperature and 400ppm $CO_2$), an elevated $CO_2$ group (ambient temperature and 800ppm $CO_2$), an elevated temperature group (ambient temperature+$6^{\circ}C$ and 400ppm $CO_2$) and an elevated temperature/$CO_2$ group (ambient temperature+$6^{\circ}C$ and 800ppm $CO_2$). Compared with the control, plant height, branch number and leaf number increased under the elevated temperature and elevated temperature/$CO_2$ group. However, leaf area and chlorophyll content showed a tendency of decreasing in the elevated temperature group and elevated temperature/$CO_2$ group. The number of flower and bud were decreased in the elevated temperature and elevated temperature/$CO_2$ group (mean temperature at $26.8^{\circ}C$) during the growth period. The total number and the weight of fruits were decreased in the elevated temperature group and elevated temperature/$CO_2$ group more than the control group. While the weight, length and diameter of fruit decreased more than those of control as the temperature and $CO_2$ concentration increased gradually. This result suggests that the fruit yield could be decreased under the elevated temperature/$CO_2$ ($6^{\circ}C$ higher than atmospheric temperature/2-fold higher than atmospheric $CO_2$ concentration), whereas the percentage of ripen fruits after 100 days of planting was increased, and showed earlier harvest time than the control.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.78-82
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• 2022

Phenology determines the timing of crop development, and the timing of phenological events is strongly influenced by the temperature during the growing season. In process-based model, leaf area is simulated dynamically by coupling of morphology and phenology module. Therefore, the prediction of leaf appearance rate and final leaf number affects the performance of whole crop model. The dataset for the model equation was collected from SPA R chambers with five different temperature treatments. Beta distribution function (proposed by Yan and Hunt (1999)) was used for describing the leaf appearance rate as a function of temperature. The optimum temperature and the critical value were estimated to be 26.0℃ and 35.3℃, respectively. For evaluation of the model, the accumulated number of onion leaves observed in a temperature gradient chamber was compared with model estimates. The model estimate is the result of accumulating the daily increase in the number of onion leaves obtained by inputting the daily mean temperature during the growing season into the temperature model. In this study, the coefficient of determination (R²) and RMSE value of the model were 0.95 and 0.89, respectively.