Duration of the vegetation period, phases of growth and development of soybean depending on sowing terms

Abstract

Purpose. To study the influence of sowing terms on soybean varieties interphase and vegetation period duration in the Western Forest-Steppe. Methods. Field (visual and phenological observations of the growth and development of soybean plants); statistical (statistical processing of research results). Results. The research was conducted at the Khmelnytskyi research station of the Institute of Feed Research and Agriculture of Podillia of NAAS during 2016-2020 on the podzolic medium loam black soils. Weather conditions in the years of research at the time of soybean sowing were different, which allowed studying the impact of the studied factor on the “sowing-seedlings” period duration. Summarizing the results of observations, it was found, that on average over the 5 years of research, it made up 17-20 days for early, 11-14 and 10-13 days – for optimal and late sowing terms, respectively. It should be noted that high average daily air temperatures, high rainfall with uneven distribution and significant deficit in some phases of soybean development had a considerable impact on the duration of the growing season, plants growth and development, formation of their individual productivity and seed yield of all the studied soybean varieties. According to the results of the five-year research, it was established, that the longest duration of all interphase periods was observed at the early sowing terms, the shortest – at the optimal and late ones. In general, the period of “seedlings-ripening” was shorter at the optimal sowing period by 3-4 days, at the late – by 1-2 days compared to the early sowing terms. Among the soybean varieties of domestic selection studied in conditions of the Western Forest-Steppe, the shortest “seedling-ripening” period was observed in the KiVin soybean variety (106-109 days), the longest (114-118 days) – in the Triada one. In other soybean varieties it ranged from 107 to 112 days depending on the time of sowing. Conclusions. The most effective for the conditions of the Western Forest-Steppe are optimal and late sowing terms at which seeds are sown in a wet seed bed, precipitation falls in the critical for the growth and development of soybean plants period, and duration of the interphase and vegetation periods are generally optimized.