Soybean seed hardness in the right-bank Forest-Steppe of Ukraine

Abstract

The article presents results of a three-year observation of soybean seed dormancy. We investigated causes of the phenomenon of "seed hardness" in soybeam. This factor was shown to depend on soil-climatic conditions of the crop vegetation period.The aim and tasks of the study. So far, soybean hardness has been inconspicuous in the Right Bank Forest-Steppe of Ukraine. Under the hydrothermal conditions of the growing season in 2015, on ultralow moisture provision accompanied by high air temperatures during seed formation and maturation, the “seed hardness” phenomenon was observed in some soybean varieties. In this regard, a demand to investigate causes of this phenomenon and to find ways to overcome it arose.Material and methods. The study material was seeds of 13 soybean varieties belonging to various ripeness groups bred at the Institute of Feeds and Agriculture of Podillia of NAAS. Sowing qualities of seeds were determined as per All-Union State Standard 4138-2002 "Agricultural Crop Seeds. Methods of Quality Determination" in 2013–2015.Results and discussion. The weather conditions were shown to considerably influence the sowing qualities of seeds. Determining the laboratory germinability of harvested in 2015 soybean seeds of varieties belonging to various ripeness groups, we observed a significant percentage of hard seeds in some soybean varieties. This phenomenon was not noticed for seeds harvested in 2013 or in 2014. Incubating seeds in a germinator for 5 additional days, we observed that seeds that had been hard, when we evaluated the germinability, came out of dormancy slowly and partially germinated. Extension of the germination period led to germination of 4–7% of hard seeds. On day 13 of germination, the number of hard ungerminated seeds ranged from 4 to 11%Conclusions. Extension of the soybean germination period by 5 days increased the number of seeds that gave seedlings on average by 4–7%. All seed samples after extended germination met the state standardization requirements