The study was conducted in a four-year-old apple plantation located in RBM “Vrazhdebna”, Sofia during the winter of 2009/2010. The trees were formed with a freely growing crown. The objects of the study were the apple varieties Golden Delicious and Starkrimson. There is no sufficient data on the role of an improved leaf feeding diet for the resistance of fruit plants in overcoming various stress situations caused by extreme temperature or water regime. To give a clarification on this issue, we conducted our study in order to investigate the effects of foliar feeding with Lactofol bio-mineral fertilizers on the cold resistance of apple cultivars. We confirm that leaf feeding reduces damage caused by low temperatures in the vegetative organs of apples by 4%–9%. Improved diet with Lactofol contributes to better tissue maturation and differentiation of buds on the apple trees, resulting in lower annual percentages of damaged shoots and fruit buds.
Study of the effect of foliar feeding with Bulgarian Lactofol suspension fertilizers in apples exposed to temperature stress