INFLUENCE OF SOWING DATES ON THE LINEAR SIZES OF CORN HYBRIDS

In the studies, three periods of early sowing were studied at the level of soil temperature (LTS) at the depth of seeding +8°С, average for LTS - +10°С and late at LTS - +12°С, hybrids of maize of different groups of ripeness (early- – Kharkiv 195MV, DKS 2870, DKS 2960, DKS 2949, DKS 2787, DKS 2971 (st), mid-term – DKS 3476, DKS 3795, DKS 3472, DKS 3420, Pereyaslavsky 230СВ, DKS 3871 (st) and mid-ripening – DK 391, DKS 3511, DK 440, DKS 4964, DKS 4626, DK 315 (st)). The results of researches have revealed that the length of the vegetative period of plants (factor A) has a significant impact on plant height. So in the group of early-frozen maize hybrids the height of the plants was 250.3 cm, in the middle hybrids – 271.5 cm, and the average hybrids – 277.6 cm. Extension of the length of the growing season increases the height of plants in maize hybrids. Іn the group of early-hybrid hybrids, on average for three years of research, the highest plant height was shown by hybrids such as DKS 2787 – 266.9 cm, DKS 2870 – 264.2 cm and DKS 2971 – 264.0 cm, the least high in the given the group of hybrids was DKS 2949 – 222.3 cm, DKS 2960 – 236.2 cm and Kharkiv 195MV – 248.2 cm. This applies to mid and midhybrids. The highest value of plant height was obtained at an early sowing date, compared to the middle and late. Thus, in the group of early-hybrid hybrids, it was 255.7 cm, medium-longest – 278.9 cm, and medium-sized – 283.3 cm, while in the second (average) period the plant height was 250.7 cm, 270.2 and 278.8 cm, and at the third stage of sowing – 244.6 cm, 265.3 and 270.7 cm, respectively, for the early-eastern, middle-aged and middle-aged groups. Estimation of variation of plant height by coefficient of variation (V) and height alignment showed that variation of plant height of stem in the aggregate of investigated maize hybrids has low (2011-2013) variation value (V = 6.30-6.97). In addition, the plant height also has a significant effect on the time of sowing. Thus, when applying the early term of sowing, the maximum value of plant height in the hybrids studied is obtained, and, on the contrary, the delay with the terms of sowing leads to a decrease in the linear sizes of plants