PLANT TOLERANCE TO NICKEL TOXICITY .1. INFLUX, TRANSPORT, AND ACCUMULATION OF NICKEL IN 4 SPECIES

Plant tolerance to nickel (Ni) toxicity depends on plant differences f or uptake and distribution within tissues. Differences among and withi n species for Ni tolerance/accumulation might be used to identify or d evelop plants for remediation of high Ni soil conditions. Solution cul ture experiments were conducted under controlled conditions to determi ne influx (IN) into roots, transport (TR) from roots to shoots, and ac cumulation of Ni in four plant species grown at different Ni levels. W hite clover (Trifolium repens L.) had high dry matter (DM) at high Ni levels because of its low IN and TR of Ni. At Ni levels <60 mu M, maiz e (Zea mays L.) had high DM probably because of its low TR even though it had high IN of Ni. Ryegrass (Lolium perenne L.) was sensitive to N i toxicity because of its high IN and TR of Ni. The sensitivity of cab bage (Brassica oleracea var. capitata L.) to Ni toxicity was correlate d with high TR even though it had low IN of Ni. Nickel accumulation in shoots was relatively high for cabbage and low for maize. Maize avera ged similar to 60-fold less Ni in shoots than cabbage and similar to 1 0-fold less than ryegrass when plants were grown with <120 mu M Ni. Pl ant tolerance to Ni toxicity was related to low IN of Ni, and especial ly to TR of Ni. Selecting or developing genotypes with low TR of Ni mi ght improve plant tolerance to moderate Ni toxicity and reduce the flo w of Ni from contaminated soils to shoot organs.