Germination Behaviour of Seeds as Affected by Different Temperatures in Some Species of Brassica

Abstract

Germination tests of seeds were carried out at 5 different temperatures, i. C., 5, 15,25,35, and 45`C, using 11 different crops of Brassicu. Germination was examined every two hours and, afterwards, every 12 or 24 hours. In every crop, seeds began to germinate earliest at 35'C and latest at 5`C. The start of germination became later in the decreasing order of temperature from 35 to 5'C. Seeds at 45'C began to germinate as early as those at 35'C in many crops, but in some crops the start of germination was much delayed. Mean germination period was shortest at 35-C, and shorter at 25'C in every crop. These temperatures were followed by either 15 or 45`C with respect to mean length of period. The longest period was needed for germination at 5 C. As for germination percentage, seeds at 35,25 and 15'C showed more than 85% in all of the crops examined. At 45 or 5'-C, low percentages of germination were frequently observed. Differences among crops were observed at these temperatures : some crops showed bad germination at 45C, and some at 5'C, and others at both 45 and 5-C. The response of non-dormant seeds was different from that of dormant seeds in terms of germination temperature. Optimum temperatures for germination of non-dormant seeds were higher than those of partially dormant seeds.