Studies on the fruit setting and development of sweet peppers

Abstract

Fruiting behavior of sweet peppers (var. Miekairyo and Sakigake-midori) was investigated under greenhouse conditions using sand culture technique.At the same time the effect of heavy nitrogen application and low light intensity on the fruiting behavior was evaluated.1. With an increase in the number of flowers a rapid increase in the bearing number of fruits was found, but subsequent flowering was arrested showing the lowest number of flowers at about the time of the highest number of bearing fruits.2. Both in autumn and spring crops a rapid increase in the bearing number of fruits to a peak value occured about one month after the commencing of the fruit setting. This was followed by a decline, reaching the lowest value one month after a peak value. Then the second increase was induced again.3. As the number of bearing fruits increased, the percentage of fruit setting rapidly decreased and reached the lowest value at the time of the peak value of bearing fruits. And then fruit setting increased again with a decrease in the bearing fruits.4. Thus it was clearly found that cyclic fruiting occurred on alternate months.5. From the data it appears that fruit setting is affected by internal factors than by daily weather conditions.The percentage of fruit setting on main stem was fairly constant showing about 80 percent, while that of lateral branches showed 30 percent on the average, but the fruit setting varied in the range of 10 percent at the time of the peak value of bearing fruits to almost 100 percent at the time of the lowest value.6. Flowering was considerably inhibited by rainy or cloudy days. However, in spite of successive bad weather conditions flower buds eventually opened.7. It was clearly shown that fruit development was affected by night temperature than by day temperature. The higher the night temperature in the range of 22 to 16°C, the more rapid the fruit develops.8. Heavy nitrogen application or low light intensity did not induce a change in cyclic fruit rhythm, but induced low peaks and deep valley compared with plants grown under high light intensity and medium nitrogen application. Apparently low light intensity gave greater changes in the percentage of fruit setting than heavy nitrogen applications.