The results of the research of the mass of 1000 grains and productivity depending on the covering depth (4 cm, 7 and 11 cm) and the sizes of fraction of seeds (small, medium and large) of corn hybrids of three groups of ripeness (earlyripe group - DKC 2960 and DKC 2971, middle-early group - DKC 3472 and DKC 3795, mid-season group - DK 315 and DKC 4082 of “Dekalb” company of Monsanto Ukraine) are given in the article. Field, laboratory and statistical methods were used during the research. In the group of early-ripe hybrids, when using a large seed fraction at a sowing depth of 4 cm, the weight of 1000 seeds was DKS 2960 - 248.3 ha, DKS 2971 - 254.8 ha, when sown to a depth of 7 cm - 244.6 and 251.1 ha and at a depth of 11 cm - 248.9 and 250.9 ha, respectively. The middle-early group of hybrids had the mass of 1000 seeds in the range of 222.1-294.4 ha. In the hybrid DKS 3472, when sown with small seeds at a depth of 4 cm, the mass of 1000 seeds was 253.1 ha, at a depth of 7 cm - 249.7 ha and at depth 11 cm - 242.8 ha. The use of a middle fraction of seeds at a depth of 4 cm provided the mass of 1000 seeds at the level of 263.3 ha, 7 cm - 257.0 ha, 11 cm - 262.5 ha. Large seeds at sowing to a depth of 4 cm provided the mass of 1000 seeds of 267.3 ha, 7 cm - 265.4 ha and 11 cm - 259.4 m. A similar situation in the mass formation of 1000 seeds, depending on the depth of sowing and the mass fraction of the seeds was and in the middle-early hybrid of corn DKS 3795. In the mid-season group of corn hybrids, the mass of 1000 seeds varied from 208.8 to 281.4 m. The largest weight value of 1000 seeds is formed at the depth of covering of 4 and 7 cm, an increase in the depth of covering up to 11 cm usually leads to decrease in the mass of 1000 seed of studied hybrids. In 2015, due to a lack of moisture during the formation and filling of grains, there was a great slump in the mass of 1000 seeds compared with 2014 and 2016, which were more favorable for moisture availability. The highest level of yield of the DKS 2960 hybrid was obtained using a large seed fraction - 8.55; 8,46 and 8,67 t / ha, respectively, at the depth of covering of seeds 4; 7 and 11 cm. In the group of middle-early hybrids, the growth of productivity of crops was noted in comparison with earlyripe seeds. The most productive hybrids were representatives of the group of mid-season seeds. So in the DK 315 hybrid, the yield of grain at the use of the small fraction, on average for three years, was - 9.53; 9.46 and 9.11 tons / hectare, at sowing the medium fraction - 10.03; 10.86 and 10.2 t / ha, and at sowing thelarge fraction of 10.31; 10.52 and 10.31 t / ha, respectively, at the depth of covering the seeds to 4 cm, 7 and 11 cm. In the DKS 4082 hybrid, the yield of grain at sowing of the small fraction was 9.49 t / ha, 9.35 and 9.05 t / ha, the medium - 10.06 t / ha, 10.56 and 10.62 t / ha, the large - 10.11 t / ha, 10.5 and 10.53 t / ha, respectively, at the depth of 4 cm 7 and 11 cm. So, the grain yield significantly depended on the climatic conditions of the year. An increase in the depth of covering of small seeds leads to a decrease in the productivity of corn hybrids, while an increase in the depth of covering of the medium and large fraction of seeds to 7-11 cm does not cause a sharp decline in yield, especially in the mid-season group of hybrids. The use of large and medium seed fractions positively affects the increase of grain yield compared with the small fraction
