Purpose. To determine the manifestation of biometric features of corn hybrids of various FAO groups and find out their relationship with grain yield when grown under drip irrigation in the Southern Steppe of Ukraine. Methods. Field, laboratory, mathematical and statistical. Result. Corn crops treatment with micronutrients had a positive effect on the height of hybrids in some phases of growth and development. The greatest influence on growth processes was caused by complex microfertilizer Avatar-1; it provided a growth in plant height as compared to the untreated control, by 1–7 cm. The use of Nutrimix microfertilizer, in general according to the variants of the experiment, influenced growth processes minimally (acceleration in phases of growth and development of the agriculture crop was 1–3 cm). Plants of the mid-late ‘Chonhar’ hybrid (FAO 420) were the highest throughout the growing season among the studied corn genotypes. This figure reached a maximum in the stage of milky ripeness when plants were treated with Avatar-1 – 267 cm. It was revealed that there is a close correlation between plant height and grain yield. Conclusions. The ratio of the height of hybrid plants by groups of ripeness and level of productivity showed that for medium-early groups in the phase of linear growth termination the optimum height was 240–250 cm, in this case grain yield was 11.2–11.5 t/ha, for the middle-ripening group – 255–257 cm with a grain yield of 11.8–12.1 t/ha. For mid-late maturity hybrids the optimum plant height for high yields grain (more than 13 t/ha) was in the range from 265 to 270 cm. The optimum height of plants and the maximum yield can be achieved under irrigation using corn hybrids of the corresponding groups of ripeness and the use of complex micronutrients.

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