SYSTEM OF SEED PRODUCTION AND BASIC PRINCIPLES OF CHOICE HYBRIDS OF CORN

Abstract

Purpose is to identify optimal schemes for hybrids parent forms sowing at the areas of corn hybridization for the most complete pollination and seeding of ears. Development of the main criteria for the selection of corn hybrids based on modern data of climate changes, biological peculiarities and traits of new corn hybrids. Methods. Experiments were carried out according to generally accepted methods for plant breeding, the method of split plots. Results. The corn seed production system consists of several stages: 1 – development and reproduction of self-pollinated lines; 2 – production and reproduction of parent forms seeds; 3 – production of seeds of the first generation (F1); 4 – post–harvest processing of seeds at seed factories. In the company seed production system, all stages of production are concentrated in one plant, the soil control of each batch of seeds is carried out in winter nurseries in the southern hemisphere of the planet, and in the winter period the level of typicality and varietal purity of hybrids is determined long before the start of seed sales. Growing the seeds of the first generation hybrids is carried out on the hybridization plots by sowing parental components with alternating rows of maternal and paternal forms at the ratio of 2:1, 3:1, 4:1 and 5:1 (sowing schemes, respectively, 4:2, 6:2, 8:4 and 10:2). The 6:2 sowing scheme is the most common and technologically convenient. As the rows of plants of the maternal form move away from the parental form in the hybridization areas, the degree of fertilization and the grain size of the ears decrease from 88–90 to 65–67 % and below. The location of corn hybrids from the southeast to the northwest of Ukraine is accompanied by an improvement of the conditions of moisture supply and a decrease in the amount of solar radiation and heat, which extends the vegetation period of hybrids by 7–14 days and increases the grains moisture content. The terms of the main phases of development (flowering, formation and pouring of grain) for hybrids of different maturity groups occurs at different times, which may or may not coincide with air or soil drought, heat, etc. In order to prevent yield losses with a single hybrid in the farm, it is advisable to sow several hybrids of different maturity groups. Conclusions. The distance between rows of parent components should not exceed 2.1 m, at which the degree of seeding of ears of the mother form is more than 80 %. The 6:2 scheme is the optimal scheme for sowing parental forms on the hybridization plots. For grain cultivation, one should take into account important economic characteristics of corn hybrids – grain yield and moisture content, as well as adaptive possibilities of hybrids – cold resistance, heat resistance, drought resistance. In order to avoid the negative impact of climate changes, it is recommended to sow several corn hybrids of different maturity groups.