FEATURES OF THE MANIFESTATION OF BIOMETRIC INDICATORS IN VARIETIES AND BREEDING LINES OF BREAD WINTER WHEAT ON THE AUTUMN VEGETATION DORMANCY ONSET DATE IN THE FOREST-STEPPE OF UKRAINE
Authors: Rysin A. L. , Volohdina H. B. 
Published: October 2023

The duration of the autumn vegetation period of plants depends significantly on the meteorological conditions of the year, the sowing date and the date of seedling emergence. Ensuring optimal parameters of bread winter wheat crops on the autumn vegetation dormancy onset date is one of the most difficult tasks in the cropping practices. It is well known that almost all agrotechnical techniques used during the autumn period, or even before sowing, have a great influence on the plant tillering, their mass, stem density and their physiological state on the autumn vegetation dormancy onset date. Different sowing dates have an impact on the canopy density per unit area, plant growth and development in the autumn period, disease damage, overwintering, and ultimately on productivity, since all generative organs are iniciated in the early stages and subsequently form the adaptive properties of plants to adverse conditions conditions of winter or spring-summer periods. Therefore, establishing the features of the autumn development of bread winter wheat plants from year to year remains an urgent issue in terms of both food and economic security of the state. Goal. To identify the peculiarities of the manifestation of biometric indicators in the genotypes of bread winter wheat on the autumn vegetation dormancy onset date in the conditions of the central Forest-Steppe of Ukraine. Methods. Field, laboratory, statistical. The results. The weather conditions of autumn in 2018–2020 were quite contrasting, differing in terms of both temperature and amount of precipitation. It was established that under a favorable hydrothermal regime (in 2018), the level of manifestation of plant biometric indicators was maximal, which ensured the rooting of bread winter wheat plants and the formation of fully above-ground biomass, and in conditions of soil and air drought (in 2019) it was minimal, which led to the problem of obtaining timely and even emergence of winter crops. Shifting the sowing dates to later ones (October 15) led to their significant decrease. It was found that the dominant role in terms of influence belonged to the weather conditions of the year with part of influence occupied 26.5÷70.6%. It was studied that leaf number and plant weight decreased sharply under stressful conditions, and the variation increased under the conditions when sowing on October 5, which must be taken into account in management the breeding process, estimation of source material and selection of genotypes with the specified parameters. It was noted that the breeding line LUT 55198 had the highest biomass on average in the experiment over three years of the research, on the autumn vegetation dormancy onset date it formed a phytocenosis with 1.54 pcs stem number per plant, 3.86 pcs leaves, 14.28 cm in height, 0.49 g raw plant weight.. The maximum level of manifestation of the indicators was when sowing on October 5: stem numbesr were 2.84 pcs. (in 2018), 2.0 pcs. (in 2020), and 1.95 pcs. (on average over three years); plant weight was minimal 0.29 g (in 2019) and 0.65 g (on average over three years). When sowing on October 15, the same trend was noted regarding plant weight in 2018 (0.52 g), 2019 (0.15 g) and on average over three years (0.33 g). The variety MIP Dniprianka also formed a high level of above-ground biomass on the autumn vegetation dormancy onset date and significantly exceeded the standard variety Podolianka according to the average biometric indicators: the plant mass was 0.44±0.02 g and 0.36±0.01 g, respectively; plant height was 13.83±0.35 cm and 12.00±0.32 cm, respectively. The breeding line ER 55023 and the variety MIP Lada had increased tillering number when sowing on October 5, namely 1.88 and 1.87 pcs, respectively, and when sowing on October 15, 1.31 pcs (maximum level) was noted for the variety MIP Lada. Under favorable thermal conditions and moisture availability (sowing on October 5, 2018), the breeding lines LUT 55198, ER 55023 and the variety MIP Lada fully realized their biological ability to form an increased number of stems during the tillering period (2.84, 2.64 and 2.72 pcs, respectively). The variety MIP Yuvileyna, on the contrary, had the minimum level of the indicator on average according to the experiment 1.25 pcs. Prospects. The peculiarities of the manifestation of biometric indicators in bread winter wheat on the autumn vegetation dormancy onset date were established, they significantly depended on growing conditions, sowing dates, genotype and directly influenced the growth and development of plants, programming the level of their productivity in the future, and the interaction of factors in the conditions of the central Forest-Steppe of Ukraine. It is worth noting that there is a stable tendency to the formation of higher values during the first sowing date (October 5) as compared to the second date (October 15), regardless of the conditions of the growing year in all varieties and selection lines under study. They can be characterized by their adaptive properties as intensive ones with a pronounced reaction to the environment, that is, a relatively high yield may be the result of a specific effect on more favorable growing conditions. The rational ratio of water and heat resources was ensured by the best sowing dates, due to which the plants accumulated sufficient above-ground mass, formed tillering node and root system. The breeding line YUT 55198 and the varieties MIP Dniprianka, MIP Lada were singled out, which on the autumn vegetation dormancy onset date stably prevailed over the standard variety Podolianka in most of the biometric indicators.