Fruit Development and Quality of Hot Pepper (Capsicum annuum L.) under Various Temperature Regimes

Hot pepper (Capsicum annuum L.) originated in South America and is cultivated worldwidely in many temperate regions as well as subtropical and tropical regions. During the growing season, various climatic and soil factors, including air temperature, light intensity, precipitation, and soil conditions, affect the growth and development of hot pepper plants. Temperature is one of the major environmental factors affecting processes such as flowering, fruit set, and fruit growth. This study investigated the effects of temperature on the vegetative growth, fruit development, and fruit quality of hot pepper cultivar 'Muhanjilju' to develop a cropping system for producing high-quality fruit in temperate regions. The temperature range of 20 - 25 degrees C was favorable for vegetative growth and fruit development. However, a temperature of 30 degrees C reduced fruit development, including fruit set and fruit growth, although it enhanced vegetative growth, and a temperature of 15 degrees C caused short plant height, a small number of branching nodes on the main branch, and elongated fruit. At 20 - 25 degrees C and 30 degrees C, the fruit development period was shortened by 9 - 16 and 22 days, respectively, compared with that of plants grown at 15 degrees C. In addition, the change in fruit color was advanced significantly at 20 - 25 degrees C and 30 degrees C. A high temperature of 30 degrees C not only reduced the total number of fruit but also caused the formation of short or malformed fruit. Furthermore, the total free-sugar content of red ripe fruit increased significantly at 20 - 25 degrees C, while the capsaicinoid content of red ripe fruit increased as temperatures increased in the range of 15 - 30 degrees C. These results indicate that the temperature range of 20 - 25 degrees C is favorable for the vegetative growth, fruit development, and fruit quality of hot pepper.