Effect of temperature on bean seed germination: vigor and isozyme expression

Abstract

This research aimed to evaluate the physiological quality of seeds and isozyme expression in seedlings of bean’s genotypes under influence of germination temperatures. Seeds of Carioca, BRS Expedito and IPR Tuiuiu genotypes were subjected to five germination temperatures (15, 20, 25, 30 and 35 °C). Seeds were submitted to tests of germination, first count, germination speed index, cold test, isozyme expression and the total dry matter of seedlings. Germination was altered due to the different temperatures. As the temperature rose, seeds of IPR Tuiuiu and BRS Expedito had reduced germination. The increase on temperature significantly affected the germination speed index of the three genotypes, leading to a greater increase in the values of this attribute. Bands of esterase from the cold test showed less intensity compared to other tests. Due to the exposure to different temperatures, there are similarities between the number and intensity of bands on esterase, with lower enzyme expression at 30 and 35 °C, changes in the number and intensity of peroxidase expression at all temperatures, and practically none expression of the acid phosphatase enzyme in higher evaluated temperatures. Therefore, the seeds exhibit better performance when exposed to temperature of 30 °C compared to use of lower temperatures, while on temperatures above 30 °C isozymes expression is reduced for both genotypes.