Evaluation of yield and stability of bread winter wheat genotypes (Triticum aestivum L.) depending on predecessors and sowing dates

Purpose. To determine the effectiveness of using contrasting sowing dates after different predecessors to assess the genotypes of bread winter wheat in terms of yield and stability. Methods. Field, laboratory, mathematical statistics. Results. A different, but reliable level of influence on the yield of bread winter wheat genotypes of such factors as conditions of the year of cultivation (66.2%), predecessors (12.5%), sowing date (6.1%) and genotype (1.7%) was revealed. Significant differences were noted in the response of the studied genotypes to the sowing date after different predecessors. Relatively less influence of the predecessors on the yield of the varieties ‘Estafeta Myronivska’ and ‘Vezha Myronivska’ was revealed, more – for the varieties ‘MIP Darunok’, ‘MIP Kniazhna’ and ‘MIP Vyshyvanka’. The sowing dates had less influence on the yield of the varieties ‘MIP Fortuna’, ‘MIP Vyshyvanka’ and ‘Trudivnytsia Myronivska’. A general tendency for decrease in the average annual yield was established in the experiment with a shift in the sowing dates from September 26 to October 16. However, for the number of genotypes after certain predecessors, the optimal sowing date was the 5th of October: after the predecessor, green-manure fallow – for varieties ‘Trudivnytsia myronivska’, ‘MIP Assol’ and ‘MIP Dniprianka’, after mustard – ‘Vezha Myronivska’, after sunflower – ‘MIP Fortuna’, after corn – ‘MIP Fortuna’ and ‘Podolianka’. In terms of sowing dates, the least variation in yield was found after the predecessors green manure, mustard and corn varieties ‘MIP Vyshyvanka’, ‘Balada Myronivska’, ‘MIP Kniazhna’, ‘Estafeta Myronivska’. Using the GGE biplot, it was found that close to the ‘ideal environment’ for the realization of the yield level of most genotypes was the second sowing date after greenmanure fallow predecessor. For different sowing dates and predecessors, on average for three years, the optimal combination of the level of yield and stability was noted for the varieties ‘Trudivnytsia Myronivska’, ‘MIP Vidznaka’, ‘MIP Assol’, ‘Estafeta Myronivska’, ‘MIP Valensiia’. Conclusions. Thus, the use of different so wing dates after various predecessors is an effective approach to organization of genotype-environmental tests. It makes it possible to identify the genotypes which are specifically adapted to certain conditions (predecessors and sowing dates) and genotypes with a relatively high level of stability when sowing after various predecessors and on different dates. This approach can be used both at the final stage of breeding to differentiate breeding lines for yield and stability, and in the development of basic elements of technology for growing newly created varieties.