PHOTOPERIODIC RESPONSE IN GERMINATION OF SEED OF CERTAIN TREES

摘要: Unstratified seeds of Betula pubescens Ehr. and B. verrucosa exhibited low or no germination at temperatures from 10° to 20 °C. unless exposed continuous illumination interrupted only by a short daily dark period. Germination was high even under primary light period if the long divided into two ones an additional Besides these true photoperiodic responses, slightly correlated intensity amount light. somewhat reduced when either decreased increased optimum. At 20° 25 °C., fair, still higher needed for maximum nearly germination. Seeds three other tree species also germinated better periods, but differences were small not significant statistically. In most experiments effe...