Effect of soil boron application on flower bud and leaf boron concentrations of olives

In this work we report the effect of soil boron application on flower bud and leaf mineral composition of olives. Two field experiments were carried out. For experiment 1, we selected ten pairs of olive trees, chosen from ten different olive orchards, half being cv. Santulhana and the other cv. Madural. On each pair, one tree was B-fertilized (+B) on 29 March 2003 with 8.3 g of B (as Borax, 11% B) and the other pair kept as control (-B). On the experiment 2, three trees per treatment of cv. Cohrancosa were subjected to soil application of 0, 2.8, 5.5, 11.0 and 22.0 g of B per tree. Flower bud samples were taken on 24 May 2003 and leaf samples on 12 July 2003 and 31 January 2004. In experiment 1, soil B applications increased B content on flower bud. However, the differences were statistically significant (alpha < 0.05) only when the ten pairs of trees (both cy.) were jointly analyzed. Mean flower bud B contents rose from 22.3 to 24.5 mg kg(-1). Soil B application also increased leaf B content in Jul. 2003 and Jan. 2004. In experiment 2, soil B application significantly increased flower bud and leaf B contents. Tissue B contents ranged from 11.4 to 20.2 mg kg(-1), 15.5 to 21.0 mg kg(-1) and 14.0 to 16.5 mg kg(-1), in flower buds and leaves on Jul. 03 and Jan. 04, respectively. Soil B applications did neither influence the N, P, K, Ca and Mg content of tissues in experiments 1 nor 2. Flower buds seem to have had access to the recently soil applied B. Leaves and flower buds developing simultaneously seem to be concurrent sinks for recently uptaken B. Early spring soil B application was effective to supply flower buds and leaves B requirements during anthesis.