Boron (B) is a micronutrient which plays an important role in crop production. Tomato is one of the crops which respond well to B application. Blossom end rot of tomato is due to the deficiency symptom of B which affects the economic value of tomato. The present investigation was undertaken with tomato (PKM 1) as the test crop to study the effect of application of boron on boron fractions viz., readily soluble, specifically adsorbed, oxide bound, organically bound, residual and total boron in boron deficient soil of Madukkur soil series. There were twelve treatments viz., soil application of boron as borax at 0, 5, 10, 15, 20 and 25 kg ha-1and foliar application of boron as borax at 0.25 and 0.50% spray twice at 50th and 80th, 60th and 90th and 50th and 90th days after transplanting which were replicated thrice in randomized block design (RBD). The results indicated that the application of 20 kg borax ha-1 recorded the highest mean value of boron fractions viz., readily soluble (0.33 ppm), specifically adsorbed (0.27 ppm), oxide bound (0.85 ppm), organically bound (0.12 ppm), residual (34.03 ppm) and total boron (35.59 ppm). Among all five fractions, residual boron contributed nearly 96.36 to 97.83% to total boron at harvest stage of crop. The results also revealed that all the five fractions of boron were decreased with progressive growth stages of crop.
Key words: Boron application, boron fractions, tomato (PKM 1).