COMPARATIVE GENETICS OF MATURATION RATE O F PLANT-SPECIES OF GENUS TRITICUM L

A comparative description is given of peculiarities of hereditary vari ability of plants of heterochromosomal wheat species with respect to m aturation rate and growth habit (357 samples of Triticum aestivum L., 136 samples of T. dicoccum (Schrank) Schuebl., and 94 samples of T. mo nococcum L. were studied). Major achievements of genetic studies of T. aestivum L. are presented; the expression of Vrn genes and their inci dence in different combinations with in the limits of a species are ev aluated in both spring samples and intermediate plants. Information on regularities of inheritance of spring growth habit in T. dicoccum was obtained for the first time. Experiments at two geographical points, differing in temperature conditions and duration of day, showed that g rowth habit of different samples (47 samples were studied) is controll ed by one or two dominant genes. One of these genes has weak expressio n in conditions of high temperature; hence, heterozygotes at this gene are tested as winter plants. Gene Vrnl(w) is frequent in T. dicoccum genotypes, as opposed in to T. aestivum (it is present in 34 samples o f 43 studied); it is a weak allele of a known Vrnl gene of common whea t. The species T. monococcum, as are the two preceding species, demons trates considerably polymorphism at the studied traits. Spring growth habit can be determined by one or two dominant genes; genes with weak expression are identified, which determine a late maturing phenotype.