PHENOTYPIC AND GENOTYPIC ANALYSIS OF SPIKE ABNORMALITY IN WHEAT (TRITICUM-AESTIVUM L EM THELL) CV PITOMA

In offspring of 4500 selected spikes (breeder's seed) in bread wheat ( Triticum aestivum L. em Thell) cv. PITOMA, 17 sterile and deformed spi kes were found. They were divided into three groups, basically by thei r phenotypic characteristics, For the purpose of detection causes of s uch phenomena, the cytogenetic analysis of seedlings obtained from see ds of atypical spikes has been carried out. The cytogenetic analysis s howed a decrease of mitotic index (MI) in Group I and Group II of atyp ical spikes (-17.5% and -61.9%, respectively) and increase of MI (14.5 %) in the third group of atypical spikes in comparison with the contro l. The frequency of chromosomal aberrations ranged from 0.5% (in Group III) to 7.3% (in Group II). The chromosomal bridges were the most rep resented types of chromosomal aberrations in all three groups. Possibl e connections between the observed spikes abnormalities and influence of herbicide Dicuran (79.25% chlortoluron) could be predicted in consi deration of the type and frequency of chromosomal aberrations.