Carbon isotope discrimination and indirect selection for grain yield in lentil, spring wheat and canola
Some researchers have proposed that carbon isotope discrimination (CID) be used to indirectly select for grain yield and transpiration efficiency in C3 plants. To determine the effectiveness of CID in indirectly selecting for grain yield and transpiration efficiency, ten diverse lentil (Lens culinaris Medikus) genotypes, ten diverse wheat genotypes (eight spring wheat (Triticum aestivum L.) and two durum wheat (Triticum turgidum L.) and ten diverse canola (Brassica napus L.) genotypes were grown in a greenhouse at 80, 50, and 30% field capacity and in the field at several locations in Saskatchewan in 1992 and 1993. In the greenhouse, above ground dry matter was harvested at 80% flowering, and data collected on water use, transpiration efficiency, weight of dry matter at flowering, and CID on dry matter at flowering analyzed. In the field, samples were collected from leaves at flowering, leaves at maturity, and kernels at maturity, and analyzed for CID. In all species in the greenhouse, genotypic differences in CID were observed under all three water regimes. For lentil and wheat, the 80% field capacity water regime provided the largest differences in CID, whereas the 30% field capacity water regime provided the largest differences in CID for canola. In all three crops, CID and transpiration efficiency were independent under all three water regimes, or when averaged across water regimes and years. The correlation between CID and dry matter at flowering was inconsistent across water regimes and years. In the field, genetic variability for CID at different growth stages and in different plant organs was observed in all three species. The genotype by environment interaction for CID was low compared to that for grain yield. In addition, the correlations between grain yield and CID in lentil and spring wheat were positive, but inconsistent across locations and years. The broad-sense heritability for grain yield was greater or similar to the broad-sense heritability of CID measurements. These results suggest that under these conditions CID could not be used effectively to indirectly select for grain yield in lentil, spring wheat, or canola.
crop improvement, crop science, plant ecology, agriculture, plant physiology, legumes, yields, rapeseed
Doctor of Philosophy (Ph.D.)