Tolerance to manganese toxicity among cultivars of lucerne (Medicago sativa L.)

Abstract

Two sand culture experiments were carried out to identify commercial cultivars of lucerne or alfalfa (Medicago sativa L.) which contain elite, Mn-tolerant plants for use in a selection programme to increase the acid-soil tolerance of this perennial legume. Differences in Mn tolerance, both within and between cultivars, were observed when a range of cultivars were exposed to regular waterings with dilute nutrient solution containing 20 or 25 mg Mn L 1. Under these moderately toxic regimes, the winter dormant cultivars Cimmaron and WL 318 were found to contain elite plants that had greater dry matter yields than their mean cultivar yield under non-toxic Mn conditions. Cultivars which contained elite, Mn-tolerant plants could not be identified by phenotypic characteristics such as their height or their toxicity symptom score, nor by their winter dormancy class. Possible reasons for the occurrence of elite plants in these cultivars are discussed. The elite, high yielding Mn-tolerant plants could not be identified from the other plants within their cultivar population by their Mn toxicity symptoms nor by their height.

Sorghum genotypic differences in tolerance to excess manganese

“…Cultivar differences in tolerance to Mn toxicity were noted at 0.37-0.46 mM Mn for alfalfa (Medicago saliva L. subsp. sativa) (Sale et al, 1992) and at 0.1-0.3 mM for sunflower (Helianthus annuus L.) (Schotz et al, 1990). Many plant species required Mn levels of only about 0.2 mM for screening purposes (Duncan et al, 1990;Foy et al, 1988;C.…”

Respostas da alfafa (>i<Medicago sativa>/i< L.) a fontes de fósforo e momento de calagem

“…Suspeitou-se que alguns sintomas que apareceram nas folhas mais velhas da alfafa durante o terceiro plantio no primeiro corte fossem o de toxidez por Mn que Nesse trabalho observou-se os mesmos sintomas descritos acima, com exceção do sintoma apresentado no Apêndice ge.Quellette & Dessureaux (citados porHelyar, 1978),Siman el at. (1974),Kelling (1990),Sale et al (1992) eDe Marco et al (1995) descreveram os sintomas de toxidez de Mn nas folhas mais velhas da alfafa como clorose nas margens dos foHolos para toxidez suave e necrose para toxidez severa. Quellette & Dessureaux 16 (citados porRobson & Loneragan, 1970), Srnith et al (1983 eKelling (1990) também apontaram como sintoma de toxidez o aparecimento de pequenos pontos necróticos nas margens dos foHolos.…”