Assessment of South African bread wheat cultivars for milling quality

[摘要] English: The objectives of this research were to assess South African winter and facultative bread wheatcultivars for milling quality, to study the effect of genotype x environment interaction on thestability of the wheat quality and to characterise the cultivars for milling performance.Thirteen hard red varieties were planted at six localities throughout the Free Sate at twoplanting dates, during 1997 to 1999. Betta-DN, Gariep, Molen, SST 367, SST 966 and Tugela-DN were planted at the first planting date. Betta-DN, Caledon, Elands, Gariep, Limpopo, PAN3235, PAN 3349, SST 124, SST 972 and Tugela-DN were planted at the second date.Material was evaluated for test weight, thousand kernel weight, kernel diameter, kernelhardness, moisture content, vitreous kernels, break flour yield, flour yield, flour colour and flourprotein content.Combined ANOVA's for the characteristics was performed over environments. Cultivardifferences were determined by means of the least significant difference at individual localities.The analysis indicated highly significant differences among genotypes, environments and GXEinteractions, for most of the measured traits. Genotypes contributed significantly to the variancein BFLY, DIAM, TKW and Hl. Environment had a large effect on TW, MOIST, VK, FLY, FCLand FPC. Significant GXE interactions were present for most of the quality traits.Canonical variate analysis was used to differentiate between cultivar groups and indicated thatTKW, DIAM, HI, BFLY and TW could effectively differentiate between cultivars. The groupsobserved with regard to the mentioned characteristics were Gariep with Betta-DN and Molenwith SST 966. Tugela-DN and SST 367 were not similar to any other cultivars. At the secondplanting date, Tugela-DN grouped with SST 124. Betta-DN, Caledon, Elands, Gariep, Limpopoand PAN 3235 formed a group. SST 972 and PAN 3349 were not similar to each other or to theother cultivars.The correlation matrix was performed, to calculate phenotypic relationships between qualitytraits. TKW had positive correlations with DIAM and these two characteristics indicated positivecorrelations with MOIST. HI correlated positively to TW and also correlated positively to VK. HIand VK correlated negatively to BFLY. High negative correlations were found between HI andFLY. FLY had positive correlations with BFLY, but correlated negatively with FLC.Stepwise multiple regressions indicated that only small percentages of the variation in TW, HI, BFLY, FLY and FLC could be explained by the other kernel and milling characteristics. HIexplained the variation in the TW the most effectively. VK and MOIST could be regarded as themost important variance predictors for HI. Predictors for BFLY were kernel size and HI. Thesecharacteristics could define 41.6 to 63.3% of the variation in BFLY. Kernel hardnessmeasurements, HI, BFLY and VK were the most definable for flour yield, together theyinterpreted up to 50.0% of the variation in FLY. TW explained less than 4% of the variation inFLY; therefore TW is not always reliable in predicting flour extraction. The kernel size explainedless than 9.6 to 20.7% of the variation in FLY, illustrating the difficulty of predicting flour yield byindirect calculations. The most important variable in predicting FCL was FLY.AMMI analysis of variance was performed to investigate the influence of the GXE interaction onmilling quality. Every locality by year combination was treated as a separate environment.Analysis confirmed differences in genotype performance, that there were varying growthconditions among the localities and the presence of GXE interactions. Interaction effects on TW,percentage VK, FLY, FCL and FPC, were large. IPCA 1 stability scores were compared to theAMMI stability values. Molen was the most stable cultivar at the first planting date. At thesecond planting date, PAN 3235 and Limpopo were the stable cultivars. Betta-DN, SST 124and Caledon were also quite stable. Tugela-DN, PAN 3349, as well as the hybrid cultivarsSST 966 and SST 972, were unstable with regard to milling quality.Milling performance, as calculated by flour extraction, ash contents and flour colour in variousformulas, revealed Gariep and Betta-DN as the high performing cultivars (first planting date),while Molen and Tugela-DN reflected poorer performances. The most effective performingcultivars at the second planting dates were SST 124, PAN 3235, Betta-DN and Limpopo. PAN3349, SST 972 and Tugela-DN indicated poorer milling performances.

[发布机构] University of the Free State