Studies on Dormancy in Woody Plants (Ⅴ) : Effects of Temperature on Terminal Bud Formation of Populus x euramericana cv. I-214.

The effects of temperature on the terminal bud formation of Populus x euramericana cv. I-214 in response to the short-day condition were investigated. Terminal bud formation was inhibited by relatively low and high temperatures during the dark periods. The optimal nycto-temperature was about 25℃(Table 1-5). Then the critical photoperiod for terminal bud formation is the longest at 25℃(Fig.1). The effective temperature during the 6-hr supplemental light period, of the 14-hr photoperiod, inducing continuous shoot growth was higher than 25℃,but the lower ones were effective for promoting terminal bud formation(Table 6). The critical length of photoperiod for terminal bud formation is considered to be varied by the temperatures of the light period and dark period and by their combination(Table 7.