Selection for Time to Maturity in Spring Wheat1
- L. S. L. Wong and
- R. J. Baker2
Numerous methods have been used to measure time to maturity in spring wheat, Triticum aestivum L. In this study, the time to complete loss of green color from the spike was used as the basis for evaluating effectiveness of selection for time to maturity and for identifying alternative selection criteria. Time to maturity and 11 other traits were measured on 50 F2-derived F3, lines in each of six crosses tested in replicated dryland and irrigated field trials. High heritabilities and high genotypic correlations with time to maturity indicated that time to full flag-leaf emergence, times to beginning or completion of spike emergence, time to anthesis, spike moisture, and number of leaves could be used as selection criteria for time to maturity. Bidirectional selection for time to maturity (10% selection intensity) showed that selection was more effective in some crosses than in others, and under irrigated rather than dryland conditions. Realized heritability for time to maturity varied from −8 ± 21% to 186 ± 50% depending on cross and environment. Bidirectional selection for number of leaves (6% selection intensity) confirmed that this characteristic is a reliable criterion for altering time to maturity. With selection differentials of 0.95 to 2.64 leaves, correlated response for time to maturity varied from 40 to 119 growing degree-days. Number of leaves and spike moisture concentration are useful methods for evaluating maturity when developmental stages cannot be measured at frequent intervals.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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