Abstract
Predicting plant responses to changing atmospheric $CO_2$ and to the possibility of global warming are important concerns. The $CO_2$ concentration of the global atmosphere has increased during the last decades. This increase is expected to result in changes of global temperatures and this will also affect the growth and development of bell pepper (Capsicum annum L.) and other crops. The objective of this study was to evaluate the effects of atmospheric $CO_2$ enrichment and high temperature on the growth and development of bell pepper under three temperature regimes. There was no statistical difference in the days required from seeding to flowering between $CO_2$ treatments, whereas among three temperature regimes, high temperature plots of $35/25^{\circ}C$ showed the shortest days (52.5 days) required from seeding to flowering. The plant height of bell peppers 15 weeks after emergence showed no statistical significance, while plots of $30/20^{\circ}C$ showed the highest plant height among the three temperature regimes. Time-course response of plant height to $CO_2$, enrichment was restrained in high $CO_2$, concentration (800ppm), at the same time higher temperature promoted plant height. Average leaf area per plant of 400ppm was $6,008.8cm^2$ and it was $5,225.1cm^2$ in the plots of 800ppm, showing 15% more leaf area compared to 400ppm $CO_2$ concentration. Leaf dry weight between $CO_2$ concentration and among temperature regimes showed a statistical significance. The average leaf dry weight in the plot of 800ppm showed the highest (44.1g), which was 18.5% higher compared to that of 400ppm (37.2g) and among temperature regimes, it was the highest (49.8g) in the plot of $35/25^{\circ}C$. Above-ground dry weight showed statistical significance between $CO_2$ concentration and among temperature regimes. The average above-ground dry weight of 800ppm $CO_2$ concentration was 141.4g, 17.9% higher compared to 400ppm $CO_2$ concentration (119.9g). Among three temperature regimes, plots of $30/20^{\circ}C$ showed the highest average above-ground dry weight (168.9g), while plots of $35/25^{\circ}C$ were the lowest (102.3g). In the average bell pepper dry weight, 800ppm of $CO_2$ concentration showed higher bell pepper dry weight (59.5g) than that (44.3g) of 400ppm of $CO_2$ concentration. It was judged that high $CO_2$ concentration was profitable fur bell pepper yield and there was a tendency that when there was high $CO_2$, concentration (800ppm), low temperature ($25/15^{\circ}C$) was profitable for bell pepper dry weight, whereas it was the reverse ($30/20^{\circ}C$), in the case of ambient $CO_2$, concentration (400ppm). In the specific leaf area according to $CO_2$, concentration, 800ppm showed 117.4, which was 35.5% higher compared to that (159.1) of 400ppm, showing that leaf becomes thicker as $CO_2$ concentration increases. Regarding correlation coefficients among crop characteristics, leaf area was negatively correlated with the number of bell peppers per plant and bell pepper dry weight, showing that the higher the leaf area, the lower the bell pepper yield. Bell pepper dry weight per plant showed positively significant correlation with the number of bell peppers per plant and total above dry weight, which showed that the higher the number of bell peppers and the total above dry weight, the higher the bell pepper yield.
[ $CO_2$ ] 농도증대와 고온조건이 피망의 생육 및 수량에 미치는 영향을 분석하여 향후 지구 온난화에 따른 작물분야에서의 대응방안 마련을 위한 기초자료를 얻고자 시험한 결과를 하면 다음과 같다. 파종 후 개화소요일은 $CO_2$ 농도처리 간에는 400ppm 처리구에서 56.3일, $CO_2$ 농도를 배증시킨 800 ppm에서는 55.7일로 대차 없었으나, 온도 처리간에는 $35/25^{\circ}C$의 고온구가 52.5일로 가장 짧게 소요되었다. 출현 후 15주의 피망의 생육 및 수량을 보면 초장은 $CO_2$ 농도간에는 유의성이 없었으며, 온도간에는 유의성이 인정되어 $30/20^{\circ}C$ 처리구에서 초장이 54.5cm로 가장 컷다. 생육기간중 경시적인 초장신장은 $CO_2$ 농도가 높은 구에서 초장신장이 억제되었으며, 온도가 높을수록 초장신장이 커졌다. 주당 엽면적은 400ppm 처리구가 평균 $6,008.8cm^2$, 800ppm 처리구가 $5,225.1cm^2$로 400ppm 처리구가 약 15% 엽면적이 높았다. 엽건물중은 $CO_2$ 농도간 및 온도처리간에 유의성을 나타내었다. 800ppm 처리구의 평균 엽건물중은 44.1g으로 400ppm 처리구의 37.2g에 비해 18.5% 높았으며, 온도처리간에는 고온구인 $35/25^{\circ}C$구가 49.8g으로 가장 높았다. 총 지상부 건물중도 $CO_2$ 농도간 및 온도처리간에 유의성을 나타내었으며, 800ppm 처리구가 141.4g으로 400ppm 처리구의 119.9g보다 17.9%나 높았다. 온도처리별 지상부 건물중은 $30/20^{\circ}C$ 처리구가 168.9g으로 가장 높았으며, 고온구인 $35/25^{\circ}C$구가 102.3g으로 가장 낮았다. 과실의 건물중(수량)은 800ppm 처리구가 59.5g으로, 400ppm 처리구의 44.3g에 비해 약 34.3% 많아 피망의 경우 $CO_2$, 농도 증대가 수량증대에 유리할 것으로 판단되었으며, $CO_2$, 농도가 높을 때(800ppm)에는 저온($25/15^{\circ}C$)에서, 평상적인 $CO_2$, 농도에서는 고온($30/20^{\circ}C$) 조건에서 수량이 높아지는 경향이었다. $CO_2$, 농도에 따른 비엽면적은 800ppm의 117.4보다는 400ppm의 159.1에서 35.5% 커, $CO_2$, 농도가 증대하면 잎의 두께가 두꺼워짐을 알 수 있었다. 또한 작물학적 특성들간 상관관계를 보면 엽면적은 주당 착과수 및 과실 건물중과 유의한 부의 상관관계를 나타내어 엽면적이 클수록 수량은 낮아졌다. 주당 과실 건물중과 주당 착과수, 지상부 총건물중과는 유의한 정의 상관관계를 보여 착과수가 많을수록 지상부 건물중이 클수록 수량이 증대함을 알 수 있었다.
