ARSENATE TOLERANCE IN AGROSTIS-CASTELLANA AND AGROSTIS-DELICATULA

Germination of Agrostis castellana caryopses is not affected by arsenate. The viability of caryopses of tolerant Agrostis castellana is lower than that of sensitive populations. The possible relation with 'cost' of tolerance is discussed. Tolerant populations of Agrostis castellana and Agrostis delicatula are clearly distinguished by their maximum root growth (MRG) from sensitive populations. The sensitive population of Agrostis castellana reaches 50% MRG reduction at 25 muM As, that of Agrostis delicatula at 60 muM As. The tolerant populations of both species do not reach 100% MRG reduction below 1280 muM As. Among the tolerant populations of Agrostis castellana we distinguish a more tolerant population with no significant MRG reduction in the range of 0-40 muM As from two tolerant populations with 10-25% MRG reduction in the same range. 50% MRG reduction occurs finally in the more tolerant population at 580 muM As, in the other tolerant populations at 320 and 230 muM As, respectively. Tolerant and sensitive populations grown without arsenate do not show significant differences in MRG. The relation between MRG and tolerance mechanisms is discussed.