DIURNALLY ALTERNATING TEMPERATURES STIMULATE SPROUTING OF PURPLE NUTSEDGE (CYPERUS ROTUNDUS) TUBERS

Experiments were conducted to determine the response of purple nutsedge tuber sprouting to diurnally alternating temperature. These experiments compared the response to alternating and constant temperatures and determined the effect of the amplitude of alternation and time of exposure to the maximum temperature. Tuber sprouting was more rapid and complete with alternating temperatures than with constant temperatures. Increasing temperature fluctuation from 0 to 6 C for 12 h daily linearly increased total tuber sprouting. As little as 30 min exposure to high temperature per day provided nearly the same level of sprouting as a 12 h alternating temperature cycle. This phenomenon should be considered when conducting studies to describe tuber temperature responses or when predicting tuber sprouting and emergence.