The research has established that the interphase periods duration depends on the plants provision with soil moisture, nutrients, moisture levels and temperature conditions during the growing season.

The research reveal various specifics of interphase periods development in durum spring wheat varieties, depending on their biological characteristics. In the Isolda variety, the interphase period of planting-tubing made 15 days on average for the research years, which is 6 days longer as compared to other varieties. Also, a longer period of tubing-earing – 14 days – is revealed, which is 2 days more as compared  with other varieties. The following interphase periods of ear-flowering and flowering-laden kernel took for 1-2 days less and made 7 days and 10 days respectively.

Germination test of the durum spring wheat seeds varieties suggests that it varies depending on the growing weather conditions. On average, over the years of research on durum spring wheat varieties it made, respectively, 79.6; 84.9 and 83.6 %. Regarding the varieties, the most significant index was recorded in the Kharkivska 41 variety (83.1 %), the least – in Giselle (77.2 %).

Low seed germination has always been the cause of poor plant survival. Plant survival is perceived as a percentage as the ratio of the number of plants before harvesting the crop to the number of the sown germinated seed. The in the formation of elements of wheat digestibility, the most notable sign is the Crops survival  during the period from full sprouting to the completion of the final stage of organogenesis, along with the seeds germination, is another significant factor of wheat productivity formation. The highest level of survival is noted in the varieties of Spadschyna and Giselle – 68 and 66 % respectively, and the least – in the Kharkivska 41 variety (62.2 %).

In the studies, the influence of the genetic content of the varieties on the formation of the density of productive stooling during the research years has been determined. The density of productive stooling fluctuation ranged in the varieties from 279 pc./m² in the Giselle to 345 pc./m² in the Isolda variety in the average for three years of the research.

It has been established that the intensity of spring wheat tillering is significantly influenced by the variety factor as well as by the years of cultivation. Thus, the productive tillering coefficient in the varieties was 1.09-1.37 on average depending on the variety. Thus, Isolda and Kharkivska 27 varieties, had a high level of productive tillering. The lowest coefficient of productive tillering was found in the Giselle variety.

An average ear grains weight during the years of the research varied in the studied varieties from 0.80 g (Isolda) to 0.98 g (Giselle). The amount of ear grains in  durum wheat varieties was influenced positively by the conditions of growing years. The largest amount of seeds on the average for the years of research was in the Giselle variety – 22.2 pc., the lowest – in the Isolda variety – 20.9 pc. The highest weight of 1000 grains were in the Giselle and Kharkivska 41 varieties – 42.2 and 43.4 g accordinly. The highest indices of the number of productive stems (345 pieces/m²) and the coefficient of productive tillering (1.37) were obtained in the Isolda variety. The Giselle variety was the best in terms of the indices of an ear grains weight (0.98 g), the number of grains from an ear (22.2 pc.) and the weigh of 1000 grains (42.9 g).

Isolda variety proved to be an intensive one according to the research results, which formed comparatively higher productivity of 4.40 t/ha and 2.55 t/ha, respectively, in the conditions of 2014 and 2015. The average yield was also determined in the Isolda variety, it formed an average yield of 2.81 t/ha, within three years of research which characterizes its plasticization.

Thus, crop yield was mainly influenced by the number of productive stems, an ear grains weight and number, which, to a large extent, depended on weather conditions.  The number of productive stalks and an ear grains weight had higher impact on the yield of the varieties.

Adaptability of durum spring wheat varieties to growing conditions is determined. The Isolda variety is characterized as the most plasticized, which ensured the highest average yield of 2.81 tons per hectare. In the Giselle variety, the least yield fluctuations were observed in the years (1.55 t/ha), which characterizes its stability under different weather conditions.

Key words: durum spring wheat, variety, weather conditions, productivity potential, yield.