Effects of transpiration rate on boron uptake by roots and translocation to shoots of table beets (Beta vulgaris L.) 1

Abstract The effects of transpiration rate on B uptake by roots and translocation to shoots of table beet (Beta vulgaris L. cv. Red Ace) plants were studied under conditions of environmental control. Plants grown under high or low relative humidities (RH) had low or high rates of transpiration, respectively. Dry weights and B contents of shoots and roots were higher among plants grown at 80% RH and B concentrations of roots were lower compared to plants grown at 30% RH. Shoot B concentrations were not affected by RH. Rates of growth and B accumulation in shoots were closely correlated for plants grown in 30% or 80% RH. These parameters were not closely correlated in roots. The rate of B uptake per g root dry weight was greater in plants having higher transpiration rates; whereas the rate of B translocation to shoots per g dry weight was independent of transpiration rate. Thus we propose that B translocation to shoots is controlled mechanistically by rates of dry matter accumulation during stages of rapid ...