COMPARATIVE RESPONSES OF TETRAPLOID WHEATS POLLINATED WITH ZEA-MAYS LAND HORDEUM-BULBOSUM L

Ten different tetraploid wheat (Triticum turgidum) genotypes were poll inated with maize (Zea mays). Fertilization was achieved in all ten ge notypes and no significant difference in fertilization frequency betwe en the tetraploid wheat genotypes was detected. A mean of 41.1% of pol linated ovaries contained an embryo. All these crosses were characteri zed by the elimination of the maize chromosomes, and the resulting emb ryos were haploids. Six of the tetraploid wheat genotypes were also po llinated with Hordeum bulbosum. Fertilization frequencies with H. bulb osum were much lower (mean = 13.4%), and significant differences betwe en the tetraploid wheat genotypes were detected. Observation of pollen tube growth revealed that part of the incompatibility reaction betwee n tetraploid wheats and H. bulbosum was due to an effect similar to th at of the Kr genes, namely pollen tube growth inhibition. These result s indicate that pollinations with maize may have potential as a broad spectrum haploid production system for tetraploid wheats.