INHERITANCE OF REACTION EXPRESSIVITY TO S HORT-DAY IN BARLEY (HORDEUM-VULGARE L)

Expression of reaction to short day in spring barley varieties (Hordeu m vulgare L.) of different ecological-geographical origin was analyzed in KV-1 climate chambers. The genotypic variation in expression of ba rley reaction to short day was revealed; it concerned ontogeny stages and the levels of phenotypic display. In direct diallelic crossings wi th four barley varieties, the inheritance of the plant reaction expres sivity to short day was determined. Varieties under study differed in the reaction expressivity, which was manifested phenotypically during formation of the generative sphere, and were neutral to light quality and elevated growing temperature. It was shown that the plant sensitiv ity to short day is controlled by four genes Ssd1-4. The dominant gene Ssd1 (insensitivity to short day) is epistatic to the recessive genes ssd2-4 (sensitivity to short day); while the dominant genes Ssd2-4 ar e epistatic to the gene Ssd1 both in the dominant and the recessive st ates. Genotypes of the varieties studied, at the loci Ssd1-4, were det ermined.