Effect of High Temperature during the Seed Development on Quality and Chemical Composition of Chili Pepper Seeds

Abstract

An analysis was performed on chili pepper (Capsicum annuum (L.) cv. Huay Si Thon and Shishito) seed vigor and quality produced by plants grown under control and high temperature conditions (29} 2/24}2 and 36 + 2/27} 2Ž, mean day and night temperatures, respectively) after anthesis to elucidate the effect of high temperature during seed development on seed quality. High temperature significantly reduced fruit growth in both varieties . More than 20 % of the seeds produced under the high temperature regime were flat with a dark brown color and did not germinate. High temperature inhibited seed fresh and dry weight increase and the seed size was slightly reduced. Standard germination of Huay Si Thon and Shishito seeds occurring under the high temperature conditions was lower than that of the control seeds by 28 and 25 %, respectively. Similarly, seed vigor was reduced, as evidenced by the reduction in the accelerated aging germination rate and the higher value of the germination index. Protein content was maximal during the early stages of seed development and decreased afterwards continuously during the seed maturation stage, while no conspicuous reduction of the protein content by heat was observed. High temperature reduced the carbohydrate content of seeds by 40 % in Huay Si Ton and 50 % in Shishito, respectively. High temperature reduced the lipid content to less than half. These results suggested that high temperature during seed development reduced chili pepper seed germination and vigor, presumably due to the limitation in the accumulation of storage products, especially carbohydrates, and lipids.