Models of sunflower productivity formation and their efficiency in the conditions of the north-eastern Forest-Steppe of Ukraine

Abstract

Sunflower crops for the production of marketable products are in all regions of Ukraine, in particular in the zone of the northern Forest-Steppe and Polissya. This zone differs significantly by soil conditions from the regions of traditional crop distribution. This condition requires theoretical generalization and experimental research to develop a model of sunflower varieties with a high level of adaptability to new growing conditions 
 In general, the assessment of the level of adaptability of genotypes to the conditions of the zone using basic cultivation technologies is provided by demonstration landfills. The most complete range of domestic and foreign sunflower hybrids focused on the area of North-Eastern Forest-Steppe and Polissya is presented at the demonstration site of the Institute of Agriculture of the Northeast NAAS. The research was conducted within the program to develop the model of the variety for the conditions of the North-Eastern Forest-Steppe and Polissya of Ukraine, (state registration number - 0116U001506). The study was performed in 2016‒2020 at the Institute of Agriculture of the Northeast NAAS of Ukraine and Sumy National Agrarian University. Hybrids (28‒56) of different originators were tested annually.
 The general dynamics of sown areas, yield and gross production of sunflower in Sumy region in 2016‒2020 is analyzed. It was established that higher crop yields compared to the average in the country, led to the increase in the annual growth in areas under sunflower from 2‒5 % in 2010 to 11‒16 % in 2019 and 2020.
 Currently, the share of sunflower crop in the structure of arable land in the region is 25.4% compared to the average of 19.7% in Ukraine Maintaining such dynamics in the near future may be the main limiting factor for productivity growth. If such dynamics will be maintained in the near future, it may become the main limiting factor for productivity growth. 
 According to the results of the analysis of weather conditions in 2016 2020, indicators of vegetative and generative development of plants of different genotypes at the demonstration site, the 2-level algorithm for realizing the generative potential of hybrids was proposed. It was determined by the length of their growing season and their place in the groups with different models of yield formation It was found that in years close to the average long-term difference in one day of the growing season was proportional to the yield ‒ 34 kg, in drier and hotter years the value increases to 50 kg/ha. 
 The ability of hybrids to provide the estimated average yield (for 3 years or more) was defined as the basic level of their adaptability to the conditions of the zone. The minimum values of indicators with a high level of correlation with the parameters of plant productivity are determined. According to the results of the analysis of values of indicators, their stability in different weather conditions the difference in algorithms of formation of productivity is established. The parameters of groups of hybrids of the model of productivity formation which provided higher than the basic level of adaptability to the conditions of the zone were analyzed.
 It was established that the model with a satisfactory level of adaptability is realized due to a slight excess of the values of the basic indicators of the parameters that determine the development of the leaf apparatus of plants and the structure of their productivity. Models with a higher level of adaptability are characterized by a significant excess of baseline values for several or most indicators.