ASSESSMENT AND GENETIC IMPROVEMENT OF ALUMINIUM TOLERANCE IN SOUTH AFRICAN WINTER BREAD WHEAT CULTIVARS

• Main Author: Motupa, Mamotlole Patricia
• Other Authors: Dr AF Malan
• Format: Others
• Language: en-uk
• Published: University of the Free State 2011
• Subjects: Plant Sciences
• Online Access: http://etd.uovs.ac.za//theses/available/etd-10192011-123240/restricted/

This study was undertaken to evaluate 11 wheat genotypes for aluminium tolerance using three laboratory based evaluation methods. Four parameters namely the root length before aluminium treatment, the root re-growth after aluminium treatment, the portion of the root affected by aluminium treatment, stained with hematoxylin and root tolerance index were measured on the two longest (primary and secondary) roots of each seedling to determine the effect of aluminium toxicity on the physiological development of the seedling roots. With the root re-growth method it was possible to distinguish between three categories of tolerance (moderate, intermediate and tolerant) that will be very helpful in future resistance breeding for aluminium tolerance. With this method it is possible to discriminate between individuals in a population for aluminium tolerance. Similar data was obtained for the primary and secondary roots, which indicated that the age of the roots are not a limiting factor for aluminium tolerance screening with the nutrient bioassay. Although the root re-growth method discriminated between the different aluminium tolerance categories, a better indication of aluminium tolerance categories was achieved with the root tolerance index method. With the above methodology in place it was possible to observe an increase in aluminium tolerance in some progeny after gene recombination and it was possible to discriminate between good aluminium tolerant progeny and progeny showing no genetic gain from the hybridisation. It was also shown that there were no reciprocal effects for aluminium tolerance in wheat. There were genetic differences for aluminium tolerance between the genotypes used in this study and this methodology can be successfully implemented in an aluminium tolerance-breeding programme for wheat. This study indicated that there is useful methodology to effectively follow the genetic gains during gene-recombination for aluminium tolerance and, secondly that there are different genetic resources available in wheat that can be utilised to increase aluminium tolerance.