Approaches to the development of durum wheat cultivars (Triticum durum Desf.) with a wide variability of the growth season

Abstract

Differentiation in the duration of the growth season is an inherent and, in many respects, decisive factor of the task-oriented formation of the cultivar pool in the region. This is because one cannot develop a universal cultivar that would be equally effective in utilization of environmental resources and equally responsive to precipitation at different stages of plant growth, to temperature backgrounds, and to the hot wind pattern. That is why the aim of the research was to find ways to extend the range of parameters of the durum wheat growth season in the Middle Volga region. Experiments were conducted to study the effects of Vrn genes (1, 2) on the structure and duration of the growth season. The chief parameters of the integral production processes were determined with regard to the early ripening. The formation of the yield components and the parameters of the growth season were tested in Harman’s system of principal components in the context of cultivar adaptability. The experiments showed the following results. (1) The diversity of durum wheat in early ripening in the Middle Volga region was determined by the predominance of genetic systems other than the system of Vrn genes. (2) Mid-ripening and mid–late genotypes had higher productivity potentials compared to early-ripening ones. In the climatic conditions of the Middle Volga region, it was due to the production of a large foliage surface and photosynthetic potential. (3) The duration of the emergence–heading time span was greatly influenced by the interaction of the cultivar–air temperature. Opposing responses were recorded in cultivars of different ecological and geographic origins, and this should be taken into account in breeding programs. (4) The strongest correlation of the yield components and duration of the growth season was observed in groups of nonadapted genotypes. (5) The variation limits of the durum wheat growth season in the Middle Volga region can be extended mainly due to the late-ripening components of cultivar pools.