Grain yield of grain sorghum hybrids of different ripeness groups depending on the influence of seeding rate and row spacing in the Northern Steppe of Ukraine

Abstract

The results of the complex influence of the row spacing and seeding rate on the grain yield sorghum of various ripeness group in the conditions of the Northern Steppe of Ukraine are presented. The studies were carried out during 2019–2021 on the fields of the farming «Dyunis» of the Kreminsky district of the Lugansk region. A three-factor experiment was laid by a rando-mized method in four repetitions. In the experiment, three variant of the row spacing were studied – 35, 45 and 70 cm, two hybrids – Swat and Flagg and four variants of the seeding rate – 100, 140, 180 and 220 thousand pieces/ha. The area of sowing and accounting plots was 100 and 80 m2 respectively. From the point of view of the yield of both sorghum hybrids, the best option was the combination of sowing with row spacing of 35 cm with a seeding rate of 180 thousand seeds/ha. The yield of Swat and Flagg hybrids on average for three years in this variant was 6.28 and 5.07 t/ha, respectively. Increasing the seeding rate to 220 thousand units/ha did not provide a significant increase in grain yield. Only in 2019, favorable for sorghum, was a significant increase in grain yield of the Flagg hybrid noted with an increase in the seeding rate from 180 to 220 thousand units/ha. At the same time, taking into account that the weather condition of the study area are more characterized by high summer temperatures and a significant deficit of precipitation, during the sowing of Swat and Flagg hybrids, as well as hybrids close to them in term of biotype, preference should be given to the seeding rate of 180 thousand pieces/ha. In the context of years of research, certain differences were noted regarding the influence of the seeding rate. In particular, in the less favourable 2020, on variant with row spacing of 35 and 45 cm, the grain yield of both hybrids on variant with a seeding rate of 180 and 220 thousand pieces/ha did not differ statistically, while on variants with row spacing of 70 cm, its increase led to a significant decrease in yield. In 2019, the highest grain yield of the studied hybrids on variants with row spacing of 35 cm was noted at a seeding rate of 220 thousand pieces/ha (6.77 t/ha for the Flagg hybrid and 5.51 t/ha for the Swat hybrid). At the same time, on the crops of the Flagg hybrid, it significantly exceeded the yield on the variant with a seeding rate of 180 thousand pieces/ha (by 0.16 t/ha), while in the Swat hybrid it was at same level – 5.51 and 5.45 t/ha respectively (LSD05 – 0.16 t/ha). Key words: grain sorghum, seeding rates, row spacing, grain yield, hybrids, feeding area shape, grain.