TRANSLOCATION OF BORON IN ALMOND TREES

Boron is generally considered to be phloem immobile in higher plants. However, recent information (Brown and Hu, 1996) shows that B may be mobile in almond tissues. This research examines the redistribution of isotopically-enriched B¹⁰ applied to mature leaves and flowers of ‘Non Pareil’ almond trees in a field experiment. Results indicated that a significant proportion of mature leaves where B was applied rapidly re-translocated to the growing fruits; 18% after 5 d and 27% after 10 d. B applications at full bloom indicated that 48% of B was recovered in fruitlets, 20% in the shoot bark and 14% in the leaves 40 d after application. These results confirm B mobility in this species.