TRANSLOCATION AND EFFECTIVENESS OF FOLIAR-FERTILIZED BORON IN BROCCOLI PLANTS OF VARYING BORON STATUS

The translocation and effectiveness of foliar-fertiilized boron (B) wa s investigated in broccoli plants supplied via the root system with lu xury, sufficient or deficient levels of B. B-10-enriched boric acid wa s applied three times to lower leaves, beginning one week prior to inf lorescence emergence, and the shoot and floret yields, as well as the B-10 and B-11 contents or concentrations of xylem sap, phloem exudate and various plant parts, were determined three weeks after inflorescen ce emergence. The amount of B-10 translocated in phloem from fed leave s to the remainder of the shoot did not exceed 0.5%, of that supplied, but it was inversely related to plant-B status. The partitioning of t ranslocated B-10 to florets (16-30%) and the degree of enhancement in floret yield (28-75%) was also inversely related to plant-B status. It is concluded that foliar-B fertilization may be more effective for pr eventing B deficiency than soil-derived B in leaves.