EFFECT OF FOLIAR FERTILIZATION ON YIELDING AND LEAF MINERAL COMPOSITION OF HIGHBUSH BLUEBERRY (Vaccinium corymbosum L.)

Foliar fertilization is fairly frequently applied besides to fertilization to the roots. In the years 2003-2005 a study was conducted on the effect of foliar feeding with phosphorus on the yielding and content of mineral element in leaves of highbush blueberry. The experiment was conducted on a production plantation, on 10-year old bushes of `Bluecrop'. The foliar fertilizer Insol Fos was applied at 4 concentrations: control - 0%; 0.4%, 0.8% and 1.2%, several times at intervals of every week (7x), every 2 weeks (4x), and every 3 weeks (3x). The first treatment was applied at the beginning of the 3(rd) decade of May and the final one at the beginning of July, minimum 7-10 days prior to the first harvest of berries. Foliar sprays with Insol Fos had a positive effect on the yielding of highbush blueberry, but it had no effect on the weight of 100 fruits. The highest concentration of the fertiliser proved to be the most effective. Irrespective of the concentration applied, in the years of the experiment the best yielding were those plants that were foliar-applied every 2 weeks. Foliar fertilization with the fertilizer Insol Fos had a varied effect on the content of mineral elements in the leaves of highbush blueberry, causing a significant increase in the content of N, P and Mg, and a decrease in the concentration of K and Ca.