Combining ability for rind puncture resistance in maize

Stalk lodging of maize (Zea mays L.) mag cause annual yield losses of more than 5%, Stalk strength can be improved by selecting for rind puncture resi stance; however, additional information on the genetic nature of rind punct ure resistance is needed. A seven-parent (B73, H111. L266, L329, L605, L668 , and L729) diallel was evaluated in 1994 and 1995 with the following objec tives: (i) to estimate general (GCA) and specific combining ability (SCA) a nd reciprocal effects for rind puncture resistance and (ii) to ascertain wh ether ear-internode data could be used in lieu of Internode 3 data. General combining ability variance was only significant at the ear internode, wher eas SCA variance was not significant at either internode. Reciprocal effect s were unimportant at either internode. For the ear internode, progeny perf ormance can be adequately predicted from GCA estimates. Inbred lines L329 a nd L729 exhibited significant positive GCA effects at the ear internode, wh ereas B73 and L668 showed significant negative GCA effects at this internod e, Inbred lines L329 and L729 could be used for developing hybrids or germp lasm with stronger stalks. Year x genotype interactions were detected for b oth internodes, indicating that genotypes should be evaluated in more than one environment. Ear-internode data provided experimental precision similar to that for Internode 3, but genetic differences among crosses were detect ed only in the ear-internode data. The ear internode provided more convenie nt and useful information on rind puncture resistance. Rind puncture resist ance of the ear internode would be a relatively easy trait to improve by pr acticing recurrent selection in a population developed from the germplasm e valuated in this study.