Articles
EFFECT OF NATURAL AND ARTIFICIAL CHILLING ON BUD OPENING AND FRUITFULNESS OF ACTINIDIA DELICIOSA CHEV. (LIANG & FERGUSON) SINGLE NODE CUTTINGS (CV. HAYWARD AND TOMURI)
Cuttings were taken from mature vines at two-week intervals starting November 16 (50% of leaf fall) through January 30. At each sampling time one third of the single node cuttings, with the base immersed in tap water, were forced in a growth chamber at 23C, 12 h of light.
The remaining cuttings were stored in a cold chamber at 5.5C in the dark and forced after receiving different amounts of chilling.
Almost all buds on single node cuttings opened without chilling or after small amounts of chilling but much greater amounts of chilling were required to obtain fertile shoots, 270 and 630 C.U., respectively for ‘Tomuri’ and ‘Hayward’. In our conditions, artificial chilling increased the number of fertile shoots in both cultivars.
The data obtained confirms the importance of chilling in bringing the bud differentiation process to its successful completion.
The efficiency of low temperature (5.5C) on the rate of bud break remains constant for long periods in ‘Hayward’ under cold chamber conditions, while outdoor conditions have a variable efficiency according to the stage of bud physiological development.
Temperatures below 0C delay bud break and flower formation.