Heat resistance of winter wheat seeds depending on preceding crops

Abstract

Purpose. To determine the dependence of heat resistance of winter wheat seeds on varietal characteristics and the influence of anthropogenic factors in different hydrothermal conditions of the year. Methods. The researches were conducted during the period 2016–2018 on new winter wheat varieties: MIP Valensiia, MIP Vyshyvanka, MIP Kniazhna, Myronivska slava, Trudivnytsia myronivska. The varieties were sown after two preceding crops, namely, green manure (white mustard) and soybean on 25 September according to agricultural practices being conventional for the zone of cultivation. Index of heat resistance of seeds was determined according to V. G. Shakhbazov’s technique by the method of thermal testing. Sowing qualities were determined according to the conventional method of State Standard 4138-2002. Results. Thermal testing showed that in seeds of winter wheat varieties grown after preceding crop green manure, after 5 minutes of warming up, the sprouting activity increased by 1.2–5.6 %, while the seed vigor and laboratory germination, on the contrary, decreased (by 7.6– 8.8 % and 7.8–8.4 %, respectively). When seeds were warmed up for 10 minutes, there was observed significant decrease in the indices of sprouting activity (by 36.4–44.0%), seed vigor (by 40.4–52.6%), and laboratory germination (by 35.4–38.2%). In seeds grown after the soybean preceding crop, the character of the changes was similar. On average over three years, according to the results of thermal testing, the lowest decrease in the laboratory germination index for both preceding crops when heated for 5 and 10 minutes as compared to the control was revealed in the variety MIP Vyshyvanka (90 % and 72 % for green manure fallow, 88 % and 67 % for soybean), and the highest decrease was in the variety Myronivska slava (86 %, 48 % and 84 %, 45 %, respectively).Conclusions. The results obtained confirm the literature data that the heat resistance of winter wheat seeds depends on varietal characteristics. The insignificant influence of preceding crops on laboratory germination under thermal testing was established. It is proposed for breeding practice to use the heat resistance index as a new variety-distinctive trait when creating winter wheat varieties.