EFFECT OF LOW TEMPERATURES AND THEIR ALTERNATION WITH HIGHER ONES ON BREAKING BUD DORMANCY OF ACTINIDIA DELICIOSA (CVS. HAYWARD AND BRUNO)

Two – year old self rooted plants of Actinidia deliciosa were used (Hayward and Bruno). Three experiments were conducted.
In the first two the plants were exposed continuously to 4°C, 7°C, 10°C, 13°C or 17°C for 250, 500, 750 and 1000 hours.
In the 3 ^rd experiment the effect of 500 hours exposure to constant 7, 13, 17 or 25°C and also the effect of 4°C or 7°C alternated with equal periods of 13, 17 or 25°C were evaluated on bud breaking.
The results indicated that a constant temperature of 4°C contributed more to budbreaking than any other of the tested constant temperatures.
Exposure to 4°C for 500 hours was adequate to reach the maximum percentage of budbreak, while 750–1000 hours required at 7°C and 10°C. Exposure to constant temperature of 17°C had a zero contribution to dormancy – breaking while continuous exposure to 13°C had very small effectiveness for rest completion.
However, when 13°C alternated with 7°C of equal duration (1 or 5 days) a synergistic effect was apparent.
On the contrary, alternation of 7°C with 17° or 25°C showed that these two temperatures were antagonistic to 7°C.

III International Symposium on Kiwifruit

I.N. Therios, I.C. Porlingis

https://doi.org/10.17660/ActaHortic.1997.444.60