FROST-INDUCED NUTRIENT DISORDERS IN INTEGRATED APPLE ORCHARD

Frost is an abiotic environmental stress factor significant hazard to many horticultural regions in Hungary. Now we should be focusing more studies on the effects of climatic changes because understanding and ability to minimise the risk of crop loss or damage is fundamental to managing a profitable enterprise. The year of 2007 was critical for Hungarian fruit growers, especially in Alföld region. Serious frost damaged was observed at blooming time in this region, which was approximately 100%. The aim of our research is to study the effects of frost of 2007 on nutrient uptake of an integrated apple orchard in North-West Hungary. Besides plant observations, macronutrient status of eight apple cultivars was studied for three years (2006-2008) to study the effects of frost on fruit load of trees and to conclude the degree and long-term impact of frost stress. Leaf N content decreased while leaf P and K was increased at all cultivars in the year of frost. In the next year leaf P and K dramatically decreased while leaf N increased and reached the earlier N level. Plant observations pointed out that the vegetative and generative balance of trees was significantly shifted due to the frost stress. Fruit loss caused higher vigour and nutrient disorder of trees. The damage not only puts at risk the current season’s fruit, but also because of the perennial nature of fruits, can influence the productivity of fruits for several seasons in the future.