Effect of Heat Stress Application to Flower and Fruit on Seed Quality of Chili Pepper

抄録

The effects of elevated flower and pod temperatures (38/22°C, DH; 30/30°C, NH; and 38/30°C, DNH, day and night temperatures, respectively) and whole plant heat stress (38/30°C, WH) after anthesis on fruit development and seed quality of chili pepper (Capsicum annuum L. var. Shishito) were investigated, compared with the control temperature (30/22°C). The highest values of fruit width, length and weight were observed at control conditions. The high temperature treatments significantly decreased fruit growth and development. DH, NH, DNH and WH reduced the growth period of ‘Shishito’ fruits by 5, 10, 10 and 15 days, respectively. Subjecting the fruit and whole plant to high temperatures adversely affected the seed set and increased the proportion of abnormal seeds per fruit. Partial heat treatments applied to the fruits decreased the carbohydrate content and reduced the germination rates and vigor of the seeds, and the most pronounced adverse effects were observed in the WH treatment. The results indicated that high fruit temperature exerted direct adverse effects on seed formation and sink strength of the seeds in ‘Shishito’ pepper. Inhibition of the assimilate supply from source organs caused by both the suppression of the sink strength and source productivity may be the major effect of heat stress on the reduction of seed quality.