INSTITUTE OF PLANT PHYSIOLOGY, GENETICS AND BIOENGINEERING
Laboratory of Physiological Genetics of Plants, Timiryazev str. 45, Almaty, 480090, Kazakhstan.
Wheat breeding for improved adaptation in Kazakhstan.
A. Kokhmetova.
Ensuring the stability of high yield under unfavorable environment conditions is the main problem facing breeders producing improved wheats adapted to Kazakhstan. The main regions of agricultural production in Kazakhstan are characterized by a lack of moisture and heat. Genotype-environment interaction also is problematic. Our goal is to study 'G x E' in order to develop stable, high-yielding, wheat cultivars and widely adapted germ plasm tailored to distinct environments. The analysis of 'G x E' in its biometrical aspects has been made on great number of winter wheat cultivars, lines, hybrids, alloplasmic lines, and other stocks. The method of Tai (1971) was used to assess stability parameters. Experimental material were grown at four locations. Abiotic-stress tolerance was studied in a series of crosses between drought- and frost-resistant local cultivars and promising lines. Targeted F1 crosses are made each year and segregating populations grown and evaluated under both favorable and stress conditions. The results of analysis of variance in all trials revealed approximately the same data. An analysis of variance was done for each test and for all characters of productivity. The genotype, environment, and 'G x E' mean squares were highly significant (P = 0.01) for all traits except tillers/plant.
The highest variability was observed in KazNIIZ, a location characterized as the most amenable for the growth and development of wheat. In the less favorable conditions of Taldy-Kurgan, the range of varitation was narrower. The least variation was observed in the extremely unfavorable conditions at Karoy. Analogous results were obtained for the average means of characters. Overall, the expression of traits decreased with deterioration of the environmental conditions. The effect of limiting factors in ontogeny has reduced the range of variation and the expression of characters. The level of homeogeneity in varieties is higher than that in hybrids. High homeogeneity of Dneprovskaya 521, Almatinskaya p-k, and Karlygash, as assessed by grain weight/plant, was controlled by recessive genes localized at unidentified loci. Each ecological zone provides a natural background for selection of plants with certain traits or sets of traits. For example, selection for reduced height was more effective in KazNIIZ, because its conditions enable the genotypic potential of this trait to be expressed to a greater extent. Irrigation and sufficient precipitation promote lodging. The genotypes were differentiated by their level of genotypical stability, and lines with these traits were selected. A strategy for selecting hybrids forms for hybridization has been outlined for each geographical region.
At present, promising genetic resources from CIMMYT (Mexico), the Wheat Genetics Resource Center at Kansas State University (USA), and the National Genebank in Tapiozelle (Hungary) are being used extensively in our wheat breeding program. These resources will enable us to produce special genetic stocks of wheat in relation to biotic stresses. The problem of wheat diseases is one of leading importance for our country.
The wheat breeding research program developed the new winter wheat cultivar Darchan in 1998. Darchan is a medium-maturity, awned cultivar. At a height of 98 cm, Darchan is resistant to lodging and frost. Test weight and baking quality are better than those of the standard cultivar Progress. This new cultivar has improved protein content and quality. Darchan is a high-yielding cultivar that yields 30 % higher than Progress. Darchan is adapted to irrigated conditions and tailored to southeast Kazakhstan.
Reference.
Tai GC. 1971. Genotypic stability analysis and its application to potato regional trials. Crop Sci 11:184-190.