Formation of biometric indicators and phenological characteristics of modern sunflower hybrids with conventional and organic growing technology in the Southern Steppe of Ukraine

The article presents the results of the analysis of the complex of basic phenological (the date of occur-rence of the main phenological phases and the duration of interfacial periods, the total duration of vegetation) and the formation of the most fundamental biometric indicators (plant height, length of internodes, area, thickness and shape of leaf blades, their pigment content, the parameters of the assimilation apparatus and differentiation of the root system of culture in the soil profile) with traditional and organic cultivation technology. The goal was achieved by laying down a two-factor field experiment in which factor A (sunflower hybrid) was presented in two variants: PR64F66 F1 and Tunca F1, factor B (cultivation technology) in five variants: traditional (intensive) control and four modifications of organic technology. The method of experience-split plots, repetition of experience – four-fold, all observations and studies were carried out on two non-adjacent repetitions according to conventional tech-niques. It is established that organic technology compared to intensive, has contributed to prolongation of the duration of the main phases of growth and development, and interphase periods (from flowering to seed ripening) for 4-5 days while reducing the duration of the starting stages of ontogenesis (the germination-the formation of baskets). Also , the index of the average height of plants decreased while increasing their foliage, linear size and area of the leaf blade, its thickness and pigment filling, reducing the length of internodes and increasing the index of leafiness of agrophytocenosis. Organic technology contributed to the more active development of the root system of sunflower and differentiation of its active mass on the soil profile. The organization of crop protection from weeds with the help of agrotechnical measures did not reduce the survival rate of sunflower plants: the number of plants killed per unit of acreage during the growing sea-son was at the level of a similar benchmark with intensive cultivation technology.