Qualitative inheritance of water-stress induced apical sterility in wheat (Triticum aestivum)

Grain number per unit area is an effective component of grain yield in bread wheat. Water-stress induced apical sterility (tip sterility) reduces the number of grains and, consequently, the grain yield in semi-arid regions with a shortage of available water during the pre-anthesis period. Crosses between apical sterile and apical fertile varieties and selection lines were made and F1, BC1, and F2 populations were subjected to moderate water-stress to study the inheritance of this character. The F2 and BC1 plants were qualitatively categorised into two phenotypes and tested for monohybrid and dihybrid segregation hypotheses. All the spikes of F1 plants obtained from crosses between apical fertile and apical sterile varieties were fully fertile indicating apical fertility is dominant to apical sterility. The F2 segregation Results from crosses between apical fertile lines and Y82187 suggested two complementary dominant genes segregating independently were involved in tolerance to water-stress induced apical sterility. In other words, two dominant genes determine apical fertility in these crosses and if one of these loci is homozygous, recessive waterstress will induce apical sterility. One F2 population segregated for both apical sterility and vernalisation response. Semi-winter plants had more sterile spikelets and the result of chi-square test confirmed monhybrid segregation for vernalisation response.