Variance, heritability and correlations in wheat hybrid populations for grain yield and other agronomic characteristics

The objective of the present work was to estimate the variance, heterosis a nd heterobeltiosis, and the narrow-sense heritability values for grain yiel d, spike length, rachis internode length and height of wheat plants (Tritic um aestivum L.), as well as the environmental, phenotypic and genetic corre lations between these characteristics. Degrees of dominance were also estim ated for all characteristics except for grain yield. The experiment was car ried out at the Experimental Center, in Campinas, Sao Paulo State, Brazil, under a screen house condition on crosses of the standard height cultivar I AC-227 (P-1) with four mexican lines: CMH 78.390/CMH 77 A.917//CMH 79.215 ( P-2), CMH 79.959/2* CNO 79 (P-3), CMH 79.481/CMH 77A.917 (P-4) and CMH 80A. 747 (P-5). The narrow sense heritability values for plant height (0.608-0. 861), spike length (0.406-0.667), rachis internode length (0.545-0.781) and grain yield (0.421-0.550) indicated that the great part of the verified ge netic variability in the hybrid populations for these traits were due to ad ditive gene action. The phenotypic correlations between plant height with g rain yield and between spike length and rachis internode length were positi ve and significant to all crosses, showing to have associations between the se characters; however the obtained results suggest that large F-2 populati ons will be required to ensure the frequency of desired recombinants, showi ng semidwarf plants with high yield potential.