|
A directional selection program was initiated to select triticale genotypes with improved aluminium (Al) tolerance and presumably acid-stress tolerance. Two consecutive cycles of 2-way selection for either high or low apparent Al tolerances from a base population, Tahara, resulted in the production of 6 selected lines, whose progenies were tested for Al tolerance response in terms of root regrowth characteristics in nutrient solutions to assess selection effectiveness. In addition, 1 cycle of 2-way selection from 2 other base populations, Empat and 19th ITSN 70-4, resulted in 4 selected lines.Selective responses differed among selected lines, depending largely on the direction of the selection made and, to a lesser extent, on the genetic background of the original population. Upward selection for longer root regrowth produced progeny with more highly Al-tolerant plants. Although varying estimates of realised heritability were generated, the 2 cycles of upward selection resulted in an enhanced Al tolerance of 14.5% in the progeny A9701 derived from the base population Tahara. These results suggest that directional selection based on longer root regrowth in nutrient solutions was effective in improving Al tolerance. A pot-culture experiment showed that the second selection generation (S2) Al-tolerant lines were more productive than their moderately Al-tolerant counterparts, further implicating the effectiveness of directional selection in enhancing Al stress tolerance and plant productivity. |
|