Maize genotypes show striking differences for induction and regeneration of haploid wheat embryos in the wheat x maize system

A number of maize (Zea mays L.) genotypes were tested for their influence o n induction and regeneration of haploid wheat (Triticum aestivum L.) embryo s to improve further the efficiency of the wheat x maize system of haploid production. Fifteen maize genotypes were crossed to five diverse wheat F-1 hybrids in a line x tester fashion in three replications. Two efficiency pa rameters, caryopses formation frequency (CFF-number of caryopses/100 pollin ated florets) and embryo formation frequency (EFF-number of embryo-carrying caryopses/100 pollinated florets), were estimated. Analysis of variance re vealed that lines (wheat genotypes), testers (maize genotypes), and their i nteraction showed significant effects on both efficiency parameters, but th e effect of maize genotypes was greater than that of wheat genotypes. The E FF of individual maize genotypes ranged from 1.1 to 23.4% and the EFF of in dividual wheat genotypes ranged from 8.4 to 10.2%. Maize genotypes also sho wed significant differences for general combining ability estimates. In add ition to EFF, maize genotypes had a striking effect on haploid embryo regen eration as analyzed using one of the wheat genotypes. The values ranged fro nt 0.0 to 87.8%. For maize genotypes producing the highest EFFs, the regene ration frequency was not necessarily higher. Hence, ne suggest a new index, haploid formation efficiency (HFE-number of haploid plants formed /100 pol linated florets), be used for identification of efficient pollinators. The HFE ranged from 0.0 to 9.9%. In this study, a pop corn cultivar, Pearl Pop Corn, was identified as the best pollinator with an average EFF of 15.1% ac ross five wheat genotypes and an HFE of 9.9% with the one wheat genotype te sted.