Study on the stability of the productivity index of sorghum (Sorghum bicolor L.) varieties under Forest­Steppe conditions

Purpose.  To determine the stability of seed producti­vity of sorghum (Sorghum bicolor L.) varieties. Methods. The research on common two­coloured grain sorghum varieties (‘Arabesk’, ‘Arkan’, ‘ES Villy’ and ‘Stepovyi’) was conducted in 2018–2020 in the Forest­Steppe zone on the experimental fields of the Poltava, Vinnytsia and Cherkasy branches of the Ukrainian Institute for Plant Variety Examination (UIPVE). In accordance with the «Methodology for the examination of plant varieties of the group of cereals, grains and legumes for their suitability for distribution in Ukraine», trials were set up, material evaluated, phenological observations and biometric measurements of plants made and harvested. Seed quality indicators were determined in accordance with the “Methodology for the qualification examination of plant varieties for their suitability for distribution in Ukraine. Methods of quality determination”. The study used field, laboratory, biochemical and statistical methods. Results. Optimal conditions of the Forest­Steppe ensured timely onset of phenological phases of plant growth and development and insignificant variation of vegetation period from 117 to 123 days. Productivity of sorghum was estimated by quantitative indicators of seed yield per plant and weight of 1000 seeds. Conclusions. The Levis coefficient CS.F was calculated to characterise the phenotypic stability of varie­ties. The results showed that ‘ES Villy’ (1.00) and ‘Stepovyi’ (1.06) were stable in the experimental field of the Poltava branch of UIPVE. The conditions of Vinnytsia and Poltava branches were more favourable for the formation of high quality bicoloured sorghum grain and larger weight of 1000 seeds.