Family and parent evaluation for sugarcane yield in early stage breeding populations in South Africa

[摘要] English: Family selection provides the potential to improve gains for quantitative traits with low heritability such as cane yield at early selection stages. Family evaluation data can also be used to identify superior parents for use in future crossing. The objectives of the study were to compare family with individual genotype selection for cane yield components; to identify and determine the proportions of elite families for sugarcane yield; to determine the optimum family selection rate and identify ideal trait combinations among the elite families; to identify superior parents using family data and determine the proportion of superior parents within populations in the Midlands breeding programmes. Family data on stalk number, stalk height and stalk diameter were collected from a sample of the first 20 genotypes per family plot. Family yield data were analysed using Statistical Analysis System (SAS) linear mixed models. Family variance was 1.2 to 5.0 times that of individual genotype variance indicating larger variability among families compared to individual progenies. Families produced larger broad-sense heritability estimates (25 to 90%) than individual genotypes (1.6 to 23.5%) suggesting that selection for superior families would be more accurate than for individual genotypes. Families produced higher predicted selection gains (9 to 59%) compared to individual genotypes (1 to 12%) which indicated that family selection would be more efficient. Results indicated highly significant differences (P<0.0001) for family and group effects for all traits. The highly significant differences (P<0.0001) observed for family within group effects for stalk diameter indicated large variability for families within the different cane yield groups. The humic soil populations produced a significantly (P<0.05) high proportion of elite families and the higher optimum selection rate (30%) compared to sandy soil trials (25%) suggested that humic soil populations contained more elite families compared to sandy soil populations. Using BLUP estimates, female (82H0397, 96H0259, 98B0460, 98S0290, 98H0590, 98S1362 and N52) and male (02S0639, 82H0397, 97B0272, 98B0460, 98B1889 and N52) parents produced progenies with significantly (P<0.05) high cane yield compared to the population mean in both humic and sandy soil populations. The identified elite parents could be used in building a core germplasm pool of genotypes that produce elite progenies. Humic soil populations contained a higher proportion of elite parents (30.6%) compared to sandy soil populations (22.5%) which is probably due to longer cycles of recurrent breeding and selection in humic soil breeding programmes. The low proportions of elite parents for both humic and sandy soil populations obtained suggest that intensive parent evaluation and development is required.

[发布机构] University of the Free State