New Sources of Aluminum Tolerance in South African Maize

Abstract

Laboratory nutrient culture techniques were used to screen maize (Zea mays L.) genotypes, including commercial cultivars as well as seed collected from traditional farmers located in various parts of the province KwaZulu-Natal, Republic of South Africa, for aluminum (Al) tolerance. Tolerance was assessed after 10 days’ growth in nutrient solutions on the basis of measurements involving Al-induced (0; 100 µM) changes in primary root growth and a loss of root apical dominance. Among the commercial cultivars Al tolerance decreased in the order Sc 602, Sr 52, Snk 2665, Kalahari Early Pearl, Ls 8501, Pan 6479, Zm 521, Sc 709. The commercial maize cultivars all had lower levels of Al tolerance to that observed in the better adapted seed collected from traditional sources (Khum, Mbon, Aj) which indicated that the fixation of important Al tolerance genes has occurred in some maize populations in response to external environmental conditions. Not all the seed from traditional sources proved to be Al tolerant (Mak, Emb, Msomi). Large intervarietal differences in root development (length and mass) were also identified. No meaningful relationships existed between Al tolerance and root development (size of root system) or between plant performance in solutions containing Al and leaf chemical contents.