THE CONTROL OF BORON ACCUMULATION BY 2 GENOTYPES OF WHEAT

The mechanism of boron (B) uptake in wheat was studied using two genot ypes with known differences in their ability to accumulate B. Influx a nd efflux of B was measured in the roots of intact 21 d old plants. Ro ots grown in 15 mu M B, when transferred to solutions containing 1mM B showed a rapid increase in B content for up to 60 min, after which no further increase was evident up to 4 h. No genotypic difference in B influx was apparent over these time periods. Roots grown in 1mM B for 7 d and then rinsed in B-free solutions quickly lost most of B that th ey contained within 1 hour; little further efflux was observed over th e following three hours. As with the influx, no genotypic difference i n B flux was evident. It is suggested that the lack of genotypic diffe rence in the short-term B fluxes could be due to a masking effect of e xtracellular B bound in the cell walls of the roots.