SOWING DATES AS A FACTOR OF SPRING SOFT WHEAT PRODUCTIVITY FORMATION IN THE FOREST-STEPPE OF UKRAINE
The research results of the phytometric indices of programmable growing of spring soft wheat depending on the sowing dates on typical low-humus chernozems in the northern part of the Right-Bank Ukrainian forest-steppe are presented. The field studies were conducted on typical chernozems of Ukrainian forest-steppe at the Agronomical Research Station of the National University of Bio-Resources and Natural Resources Management of Ukraine. It is found that in the northern part of the Right-Bank Ukrainian forest-steppe spring wheat should be sown as soon as the soil reaches physical maturity and it may be properly tilled. Sowing operations performed later than the first ten-days of April will certainly reduce crop productivity due to the following factors: accelerated plant development, reduced survival of plants during the growing season, the reduction of productive tillering, density of productive stalks, head grain content and thousand-kernel weight. Regardless of agronomic practices, the sowing dates of spring soft wheat varieties Mironovchanka and Rannyaya 93 affect the plant survival throughout the growing season, its tilling capacity, head grain content, thousand-kernel weight and grain weight per head, and ultimately the crop yield. The spring wheat variety Mironovchanka forms the yield of 5.43-5.48 t ha and the variety Rannyaya 93 - 4.99-5.04 t ha when sown during the first 10 days from the start of field operations; that is not later than the 15th of April. Sowing on later dates inevitably results in reduced yields.