EFFECT OF STRATIFICATION DURATION ON SEED GERMINATION OF SEVERAL PEACH LINE ROOTSTOCKS

Peach seeds of 'P.S. A3', 'P.S. A6', 'P.S. B2' and 'Harrow Blood' line rootstocks were stratified and chilled at 5°C. After 32 days, samples of seeds were transferred into forcing conditions (25°C), at weekly intervals, and germination time was recorded.

The 'P.S. A3' and 'P.S. A6' lines showed the maximum germination percentage after 60 days of stratification. 'P.S. B2' gave the best responses after 74 days. The germination percentage in the case of 'Harrow Blood' was lower than the other lines for almost all the stratification period.

As the germination percentage attained the maximum level, the mean germination time remained almost constant (+/- 14 days). A prolonged exposure at 5°C reduced the germination percentage in all the lines. 'P.S. B2' and 'Harrow Blood' showed a secondary response after 103 days of chilling.