COMPARISON OF POLYHAPLOID PRODUCTION FREQUENCIES IN CROSSES OF HEXAPLOID WHEAT WITH MAIZE, PEARL-MILLET AND SORGHUM

Frequencies of polyhaploid production were compared among three hexapl oid wheat varieties (2n = 6x = 42, Chinese Spring, Norin 61 and Siete Cerros) pollinated with maize, pearl millet and sorghum lines. All whe at varieties produced embryos in crosses with maize lines at frequenci es ranging from 12.6 to 26.8 %. In crosses with pearl millet lines, th e embryo formation frequencies were affected by both the wheat varieti es and pearl millet lines, In crosses with sorghum lines, the frequenc ies were highly dependent on the wheat varieties and Slete Cerros prod uced no embryos, Embryos were obtained from Chinese Spring and Norin 6 1 in crosses with all lines of maize, pearl millet and sorghum. The em bryos from crosses with maize were larger, but developed into plants a t lower frequencies than those from crosses with pearl millet and sorg hum. Most of the 377 plants cytologically examined were wheat polyhapl oids that carried a complement of 3 x = 21 chromosomes, It is inferred that maize-mediated polyhaploid production is more stable than those mediated by pearl millet and sorghum because of less genotypic effects on embryo formation.