SELENATE AND SELENITE UPTAKE AND TRANSLOCATION IN BEAN-PLANTS (PHASEOLUS-VULGARIS)

After 3 h, selenate uptake by roots of Phaseolus vulgaris L. cv. Contender resulted in more than 50% of the Se absorbed being conveyed to the aerial organs. This distribution was sensitive to respiratory inhibitors and when roots were soaked in a solution supplied with hydroxylamine, the level of Se decreased by about 80% in the whole plant, suggesting that selenate uptake requires energy. Addition of glucose to the nutrient medium resulted in slightly decreased uptake and distribution. Under the same growth conditions and 3 h incubation with selenite, a major part of the Se had accumulated in the roots, while a small fraction was conveyed towards the aerial organs. This percentage was decreased by about 20% when plants were transferred to a solution supplied with hydroxylamine, suggesting that part of the selenite entered the roots passively. Addition of glucose to the nutrient solution, resulted in enhanced levels of Se in the whole plant. Application of plant growth substances affected Se transport. When roots were incubated in abscisic acid (ABA), selenate uptake was affected, while foliar spraying of gibberellin A3 (GA3) enhanced selenite uptake and translocation.