Co-Authors:
Erez, A., Institute of Horticulture, A.R.O., Volcani Center, PO Box 6, 50250 Bet-Dagan, Israel
Yablowitz, Z., Institute of Horticulture, A.R.O., Volcani Center, PO Box 6, 50250 Bet-Dagan, Israel
Korcinski, R., Institute of Horticulture, A.R.O., Volcani Center, PO Box 6, 50250 Bet-Dagan, Israel
Abstract:
The timing of vegetative and floral bud development is crucial with regards to the potential set and persistence of the reproductive organ. Vegetative buds need normally more heat units to break than floral buds and they respond differently to higher temperatures. With peach and nectarine, vegetative and floral buds are located on the same node and in a normal arrangement of a central vegetative bud and two lateral floral buds. Competition among the vegetative and floral sinks for root supplies: water, nutrients and hormones and for carbohydrates may affect flower and fruitlet drop depending on the relative development of these two sinks. Under natural cool climate, flowers develop always quicker than vegetative buds so that when a vigorous vegetative development starts, a setting fruit is already developing. Under warm conditions however, leafing may advance to the extent that flowering will occur concomitantly with vigorous vegetative growth. This situation is exaggerated in peaches and nectarines grown under greenhouse conditions. It may often leads to poor retention of flowers and fruitlets and may cause also a drop of even large developing fruits. Use of chemicals to break dormancy may also affect the relative level of development of the vegetative and reproductive organs leading accordingly to similar effects on persistence of the reproductive organ. Chilling requirements of floral and vegetative buds, the influence of dormancy breaking chemicals and the temperature effects will be discussed.