Chilling temperature and photoperiod influence the timing of bud burst in juvenile Betula pubescens Ehrh. and Populus tremulaL. trees

Table 1 Details of the treatments received in each of the experiments during two seasons

Experiment	Plants		Chilling treatment		Forcing treatment		Recording
Experiment	Species	Number per treatment	Temperature and photoperiod	Duration (days)	Temperature (°C)	Photoperiod (h)	Frequency	Percentage bud burst
1	Populus tremula	5	Natural	35, 82	10	8, 12, 16	Daily	1st, 50 %, 100 %
1	Betula pubescens	5	Natural	35, 82	10	8, 12, 16	Daily	1st, 50 %, 100 %
2	P. tremula	8	Natural	25, 53, 76	20	10, 16	Every 2nd day	Exact count
2	B. pubescens	8	Natural	25, 53, 76	20	10, 16	Every 2nd day	Exact count

“Chilling duration” is expressed in days with average daily temperature ≤10 °C, starting from 1st September
Natural non-controlled temperatures and photoperiods, received outdoors

ISSN: 1297-966X