Comparison of What Ploidy Levels and Amphyploidy on Grain Yield and Its Components

In order to investigate the role of wheat ploidy levels and comparison them with Triticale and Tritipyrum amphyploids for grain yield and it's components, genotypes of diploid, tetraploid, hexaploid wheat, Triticale and Tritipyrum were evaluated under field condition in a completely randomized block design with three replications in autumn and spring planting seasons. The results indicated that sufficient genetic variation exist within and between species for all the traits. Effect of planting season and genotype × season interaction were significant and the traits have decreased in spring in comparison with autumn cultivation. Orthogonal comparison of species revealed that diploid wheat showed higher number spikes per m-2 and biological yield, but it produced lower level of number grain per spike, 1000 grains weight and grain yield and harvest index. Triticale produced the highest grain yield, with showing high number grain per spike and 1000 grains weight. Overall these differences could be resu-lt of genome role and planting season in preferment of the traits. The correlation coefficients between grain yield and traits indicated that, grain number per spike has higher correlation with grain yield in comparison with other traits in tetra and hexaploid wheat. One thousand grain weight showed more important role in grain yield in hexaploid wheat compare to tetrapolid wheat.