DROUGHT TOLERANCE OF THE NEW SELF-POLLINATED LINES OF MAIZE AND THE METHODS OF ITS ESTIMATION

More than half of the maize crops in the Russian Federation are located in areas with insufficient and unstable moisture. With this in mind, Z. mays breeding for drought tolerance is extremely important. The purpose of the current study is: investigate the drought tolerance of self-pollinated maize lines by various methods, identify the best samples for further breeding, establish indirect criteria for estimating drought tolerance. The study was conducted at the Agricultural Research Center “Donskoy” located in the southern part of the Rostov region, which is characterized by unstable moisture. The years of the study turned out to be dry (Selyaninov Hydrothermal Coefficient (HTC) = 0.32–0.89). The new self-pollinated lines of maize were used as initial material and studied for resistance to water stress (41 pcs. in 2011–2013, 39 pcs. in 2015–2017, 25 pcs. in 2018–2020). According to the guidelines for maize breeding, the following indicators of productivity were taken into account: number of ears per plant, weight of one ear, 1000-grain weight, number of grains per ear, etc. In 2011–2013, based on the comprehensive estimation, new middle-early drought-tolerant self-pollinated lines of maize ‘DK47111’, ‘SP203’, ‘KS211’, ‘S204’ and ‘S238’ were identified. They were characterized by the low values of residual water deficit both in the flowering (6.9 – 12.8%) and milk-wax (9.0 – 13.4%) stage, high drought tolerance index (68.6 – 85.6%), deep root system (force of uprooting the plants from the ground was 54.0–67.7 kgf), minimum gap in the flowering of male and female inflorescences (1–2 days). In 2015–2017, according to the method of residual water deficit (RWD), the following lines were identified ‘KV334’, ‘RD6’, ‘DS498/217-4’, ‘DS257/85-3’, ‘DS257/85-1’, ‘DS257/85-6’, ‘DS257/85-4’. In 2018–2020, the new self-pollinated lines of maize ‘KS317A’, ‘KV240’, ‘LSh16’, ‘S86’, ‘LSh17’ and ‘LSh2’ showed high resistance to water stress. We recommend the following selection criteria when creating new lines: absence of infertility and kernel percentage of the ears.