Regression and Cluster Analysis of Environmental Responses of Hybrid and Pureline Winter Wheat Cultivars1
- Brett F. Carver,
- Edward L. Smith and
- Howard O. England2
The commercial development and release of F1 hybrid wheat (Triticum aestivum L.) cultivars should enable wheat producers to achieve higher levels of grain production. Despite increased interest in hybrid wheat, planting of hybrid cultivars at the presentime is limited to areas traditionally having high yield potential or receiving intensive management. This study was conducted to compare yield responses of hybrid and pureline cultivars across a wide range of environments. Regression and cluster analyses were applied to data obtained from four winter wheat performance trials from 1982 to 1985. A different set of either 30 or 40 genotypes, approximately half of which were hybrids, was evaluated each year in Oklahoma. Because the environmental responses of all genotypes were highly correlated in each year, environment means were employed as the index in the regression analysis. In 1982, the average regression coefficient (b) for hybrids (1.12) was significantly greater than that for either semidwarf purelines (0.99) or tall pnrelines (0.79), indicatingreater responsiveness of hybrids to improving production conditions. For the remaining years (1983–1985), similar linear responses of hybrids and semidwarf pnrelines indicated that the hybrid yield advantage did not increase in environments with higher index values. In addition, classification of genotypes into homogeneous-response clusters according to actual responses indicated high similarity between environmental responses of hybrids and semidwarf pnrelines. Responses of hybrids and tall purelines, however, were dissimilar. The similar environmental response patterns of the most recently developed hybrid and semidwarf pureline winter wheat cultivars does not support the recommendation of either cultivar type when considering overall production potential of the environment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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