Soybean crop responses to the extreme high temperature during major development stages were explored using the crop model, CROPGRO-soybean. Specifically, we simulated the growth of soybean under abnormally higher temperatures (e.g., 39°C and 27°C for the daily maximum and minimum temperature, respectively) during the reproductive stage (R5–R7) in the past climate (1981-2010)

and as well as future (2021–2050) projected by climate scenarios. Data was modeled using 8 general circulation models of Representative Concentration Pathway (RCP) 4.5 and 8.5. The 8 future climate scenarios were collected from the CMIP5 (Coupled

Model Intercomparison Project phase 5) archive. Future scenarios of the 6 sites were spatially downscaled using a bias-corrected and non‐parametric quantile mapping method. Late-July to mid-August is an important period for crop reproduction; therefore, the temperature data used in the study was taken during these months. The Korean soybean cultivar (Taegwang) was used in this study.

We calculated the number of days on which daily maximum and minimum temperature would exceed the threshold while the cultivar is in the reproductive stage, using the 8 future scenarios of the six sites, and used that number to determine the frequency of high-temperature occurrences. The frequency at which the daily maximum temperature exceeded the threshold could not be determined for six sites during the 2050s (2021–2050). However, the frequency of high-temperature occurrences in minimum temperature increased in 5 sites beginning in the 2050s, with the exception of Hongcheon. Especially in the case of Jeonju and Miryang, the occurrence of days over 39°C increased 7 and 14 days and the frequency of duration of three days its temperature showed one and three times in the daily maximum temperature in Jeonju and Miryang, respectively, under the future climate scenario of RCP 8.5, the pathway with the highest greenhouse gas emissions as compared to the present climate. Additionally, the occurrence of days over 27°C in Jeonju and Miryang increased by 115 and 18 days respectively, while the frequency of duration of three days its temperature occurred 14 and 2 times. These critical temperatures occurred mostly during grain filling after flowering, and the crop model simulations resulted in reductions in the pod number during this period.

We again simulated the model to investigate a change in sowing dates. In Jeonju and Miryang during 1981-2010, if sowing at five days ahead from 10 June, namely in shorten of the sowing day, increase of yield potential in the average 5% was higher than reduction of yield potential in the average -1%. However, reduction of yield potential in the average -15% was higher than increase in the average 5% if sowing five or 10 days later than 10 June. In particular, relative changes for shorten of the sowing day or delay of the sowing day do not be shown in normal years which high temperatures did not abnormally occur during the growing season from 2003 to 2010. In abnormal years which high temperatures occurred during the critical period, especially R5 to R7, shorten of the sowing day affected to the increase of yield potential in average 1 ~ 3%, however, delay of the sowing day influenced on the reduction of yield potential in average -4 ~ -8%. In the result of the future climate scenario of Representative Concentration Pathway (RCP) 4.5

and 8.5 during from 2041 to 2070, the increase and decrease of yield potential for shorten of the sowing day were average +5/-5% for RCP 4.5 and average +8/-4% for RCP 8.5, respectively. Additionally, it showed average +7/-8% for RCP 4.5 and average +4/-12% for RCP 8.5, respectively in the increase and decrease of yield potential for delay of the sowing day. In addition, simulations revealed that a 2°C increase in temperature had a positive rather than a negative influence on soybean growth with no water stress. However, an increase of 4°C is expected to have a negative effect; abnormally high temperature had a greater negative impact during

the period of grain filling.

Neither research on rainfed crops nor crop modeling for Korean cultivars is popular in South Korea. The preliminary results of this study will serve to raise awareness of the importance of investigating the effects of climate change on rainfed crops in the Korean Peninsula.

1. 서론

1.1 연구배경

1.2 연구목적

2. 연구자료 및 방법

2.1 연구대상지 설정 및 자료 준비

2.2 콩 작물의 발육단계별 임계온도 설정

2.3 콩 생육 모의

2.3.1 콩 생육모형 CROPGRO-Soybean

2.3.2 품종 특성 및 모수

2.3.3 토양 입력정보

2.3.4 고온 환경 설정

2.3.5 파종일 이동

2.3.6 분석 기간과 평가 방법

3. 결과

3.1 콩 생육모형의 성능

3.2 연구대상지의 기온과 생물계절 변화

3.2.1 기온변화

3.2.2 재배기간의 변화

3.3 이상기온연도의 작물반응

3.3.1 종실비대기에서의 이상고온 영향

3.3.2 파종시기 이동에 따른 수량반응

3.4 미래기후조건 하의 작물반응

3.4.1 평년기후 대비 2°C 및 4°C 상승에 따른 작물반응

3.4.2 이상고온발생 전망

3.4.3 이상고온에 따른 수량변화 전망

4. 결론 및 다음 단계

REFERENCE