LEAF TIP YELLOWING IN EGGPLANT IS CAUSED BY BORON DEFICIENCY

In glasshouse cultivation of eggplant (Solanum melongena L.), frequent ly in March-May, the distal ends of the young, fully developed leaves become yellow. Midribs, veins, and mesophyll show the symptoms, in con trast to the magnesium (Mg) deficiency known to occur in eggplant, i.e ., interveinal chlorosis on the entire leaf. It was suggested that the symptoms were due to boron (B) deficiency although B supply was assum ed to be sufficient. Then, the uptake could be restricted. To find out the real reason and if a fertilizer other than the normally used Bora x could increase B uptake, an experiment was conducted in which 0, 5, 10, 20, and 200 mu M B as Borax and 20 mu M B as Solubor DF were compa red. Leaftip yellowing occurred at all levels between 0-20 mu M B, esp ecially at the zero level, but not at the 200 mu M B supply. Consequen tly, leaf tip yellowing can be considered as B deficiency. Borax and S olubor DF behaved the same. As long as leaf tip yellowing was moderate , it had no negative effect on production.