Selection for tolerance and susceptibility to aluminium within Trifolium repens L.

Abstract

Selections were made within Trifolium repens cv. Grasslands Huia for genotypes tolerant and susceptible to aluminium (Al). Three tolerant and 3 susceptible genotypes were crossed in a diallel design, with reciprocals bulked. Progenies were compared with Huia, the 6 parent genotypes and Lotus pedunculatus cv. Grasslands Maku for Al tolerance in soil. All genotypes selected for tolerance were more tolerant to Al than the susceptible genotypes. Similarly, the progeny from crosses between tolerant genotypes were more tolerant to Al than progeny from crosses between susceptible genotypes. Differences between genotypes for general combining ability for Al tolerance were significant at 300 and 400 ppm Al, but differences between crosses for specific combining abilities were not significant. Crosses between tolerant and susceptible genotypes showed that Al-tolerance was a recessive character in white clover. Although narrow sense heritabilities were moderately high, transfer of Al tolerance by hybridisation within white clover would be less successful than selection within a population because of the recessive nature of this character.