Features of growth of sorghum [Sorghum bicolor (L.) Moench] plants depending on the width of rows and seeding rate in the conditions of the Right-Bank Forest-Steppe of Ukraine

Purpose. To establish the optimal row spacing and so­wing rate of sorghum seeds of grain varieties ‘Dniprovskyi 39’ and ‘Vinets’, to substantiate their influence on the growing season and biometric parameters of plants in the Right-Bank Forest-Steppe of Ukraine. Methods. Field, laboratory, mathematical and statistical. Results. The most intensive growth and development of sorghum plants was observed when sowing seeds with a row spacing of 45 cm and a seeding rate of 200 thousand pieces/ha. In particular, the duration of the growing season under such conditions was the smallest: 108 days for the ‘Dniprovskyi 39’ variety and 106 days for the ‘Vinets’ variety. At the same time, the indicators of field seeds germination, plant height and stem diameter were maximum in the experiment: ‘Dniprovskyi 39’ – 88.7%, 137.3 cm and 1.7 cm, ‘Vinets’ – 86.9%, 121.8 cm and 1.6 cm, respectively. It was found that an increase in seeding rate reduced indicators of productive tillering, leaf area and weight per plant. The most intense tillering of sorghum plants was observed at a seeding rate of 150 and 200 thousand pieces/ha for all the studied variants of the row spacing: on average, up to two panicles well filled with grain per plant, depending on the varietal characte­ristics. At the rate of 250 thousand pieces/ha, tillering of plants in both varieties was somewhat weaker – 1.0–1.1 panicles per plant. The largest indicators of leaf surface area and weight of one plant were with a row spacing of 45 cm: 1528–2320 cm2 and 169.2–185.6 g in the variety ‘Dniprovskyi 39’ and 1476–2180 cm2 and 143.1–162.3 g in the variety ‘Vinets’ depending on planting density. Reduction of row spacing up to 15 cm and its increase up to 70 cm led to a decrease in the main parameters of plant growth and development. Conclusions. Sorghum plants developed better when sown with a row spacing of 45 cm and a seeding rate of 200 thousand pieces/ha, which were recommended for growing crops in the conditions of the Right-Bank Forest-Steppe of Ukraine.