Department of Plant Sciences

Boron deficiency (B) is very common in Brazilian crops. Besides the low natural concentration in the soils, its restricted redistribution within the tropical plants can be responsible for this deficiency, especially at fruits and seeds development stages. The objective of this work was to evaluate the absorption and distribution of boron in castor bean (Ricinus communis L.) through the isotope dilution technique, using 10B enriched boric acid solutions. Experimental design was completely randomized with three treatments: 1 –Application of 2.7 mg B (common boric acid) in the nutrient solution; 2 - 10B application in the nutrient solution with 1 mg B (boric acid labeled with 68.7% 10B); 3 - 10B foliar spray of 2.7 mg B (boric acid, labeled with 68.7% 10B). The experiments was carried out in green house and the castor bean plants were grown in plastic pots with nutrient solution (10 L). It was concluded that the applications of 1 mg of B in the nutrient solution (treatment 1) was more effective in increasing B content in the seed when compared to the foliar spray of 2.7 mg of B (treatment 2). The castor bean yield in the treatment 1 was higher to that in the treatment 2. Boron in castor bean is transported quickly from roots to fruits, while the transport from leaves to fruits is not enough to guarantee the normal yield in conditions of low availability of this element.