Evaluation of adaptive potential of winter wheat (Triticum Aestivum L.) varieties in the conditions of Southern Steppe of Ukraine

Abstract

The diversity of soil and climatic conditions in different regions of winter wheat cultivation leads to significant variations in yield both in space and in time. In addition, a sharp fluctuation of weather conditions, which is increasingly observed in recent years, requires a more careful choice of varieties that can provide high yield stability in stressful conditions.

Studies conducted by a number of authors provide useful information to understand the agronomic and physiological mechanisms responsible for the sustainability of yields. Different varieties can show contrasting responses to environmental conditions as a consequence of the interaction of genotype × environment. Therefore, estimating the relative contribution of the variety, the environment and their adaptation to the conditions of cultivation are important for determining the adaptation of plants, which is expressed by the ability of the variety to fully realize its productivity potential in a particular environment, despite the impact of adverse weather factors.

The goal of the research was to comprehensively evaluate the winter wheat varieties of domestic breeding according to yield, plasticity, and stability parameters, as well as to determine the interaction of the variety and the soil-climatic conditions of the Southern Steppe of Ukraine.

Field experiments were carried out during 6 years (2012-2017) in stationary crop rotation at the NNVC TSATU in Melitopol district of Zaporizhzhya region.

For the study, 11 winter wheat varieties of domestic selection were used. Method of variants placement in the experiment – complete rendomisation with three repetitions. The sowing was done each year on the 20th-25th of September after bare fallow. The cultivation technology was generally accepted for the growing zone and same for all experimental variants.

Statistical processing of the data was carried out by the method of dispersion analysis. The variation coefficient was determined by the method of B.O. Dospekhov. The index of environmental conditions was determined as the difference between the average yield of all studied varieties in particular year and the average yield in all variants for the entire trial period. The indicators of ecological plasticity and phenotypic stability were determined by the Eberhart-Russell method, and homeostaticity and the agronomic stability coefficient by the method of V.V. Khangildin.

The results of dispersion analysis indicate a significant effect (P ≤ 0.01) of all investigated factors on the yield of winter wheat. A significant share of the influence of the mutual effect of weather conditions of the year and the genotype of the variety indicates that these varieties react differently to the sharp fluctuations of hydrothermal conditions in the Southern Steppe of Ukraine, which is consistent with the results obtained in similar studies in other climatic zones. That confirms the importance of ecological evaluation of selected varieties in Melitopol district of Zaporizhzhya region in order to identify the most stable genotypes for the given region of cultivation.

According to the index of the environment, the most unfavorable conditions for the growth and development of plants were observed in 2012 and 2013, when the average yield of varieties was 2.59 and 2.70 t/ha, respectively. The most favorable conditions were noted in 2016, when average yields was 4.55 t/ha, which is almost twice more than in the adverse years.

Viktoriia odes'ka variety had the lowest average yield for the period of research, for which the given index was 72% lower than the average yield per variety. The largest yield was noted for Shestopalivka variety, which exceeded the average variety value by 20%.

As a result of the conducted research, Viktoriia odes'ka, Lyst 25, Antonivka, Hoduval'nytsa odes'ka, Shestopalivka and Misiia odes'ka were the most plastic varieties, the magnitude of the linear regression coefficient (b_і) for them was within the range of 0.83-0.93. Doskonala and Uzhynok varieties (b_і = 0.46-0.66) were classified in the group of extensive varieties, while Zorepad, Podolianka and Smuhlianka were highly intensive in the cultivation region (b_і = 1.13-1.82).

In the studied set of varieties, Shestopalivka (S_d² = 7.39) and Viktoriia odes'ka (S_d² = 11.23) were the most stable. The least stable varieties were Smuhlianka (S_d² = 144.21) and Doskonala (S_d² = 265.78). Other varieties had a middle position (S_d² = 16.70-76.32).

The maximum homeostaticity among the studied varieties was observed for the Shestopalivka variety (12.46), which was characterized by the highest yields over the years of research. Smuhlianka, Podolianka, Doskonala and Zorepad had the smallest index of homeostaticity (1.41-3.47).

Shestopalivka variety was the most agronomically valuable (As = 82%), which is consistent with its yield, plasticity, stability and homeostaticity. The smallest agronomic value was noted for Smuhlianka, Podolianka, Doskonala and Zorepad varieties. In general, the studied varieties in terms of agronomic stability were distributed in an order similar to homeostaticity.

Based on the conducted research, Shestopalivka winter wheat variety was chosen, which has high plasticity (b_і = 0.91), stability (S_d² = 7.39), homeostaticity (Hom = 12.46) and high agronomic value (As = 82% ). That is, this variety has shown itself to be the most adaptive in the given region and is most suitable for commercial cultivation in Melitopol district of Zaporizhzhya region. Smuhlianka variety had the lowest agronomic value, which is characterized by low stability of the yield over the years and therefore cannot guarantee high, stable yields.