Grain sorghum yield as affected by row spacing and fertilization practice

Abstract

Purpose. To establish varietal characteristics of yield formation in grain sorghum as affected by row spacing and fertilization system.Methods. The field experiment was carried out during the 2015–2017 period in a multifactorial stationary experiment in LLC Biotech LTD located in the central part of Boryspil district (Kyiv region) of the Left-Bank Forest-Steppe of Ukraine. Experiment design: factor A – hybrid: ‘Lan 59’, ‘Burgo F1’, ‘Briggo F1’; factor B – dose of nitrogen fertilizers: N60P60K60 (control), N60P60K60 + N20, N60P60K60 + N40, N60P60K60 + N60; factor C – row spacing: 35 cm, 50 cm, 70 cm.Results. The average yield of grain sorghum for years of research ranged from 3.98 to 9.14 t/ha, depending on hybrid, row spacing and fertilization practice. It was also found that average grain yield in 2015 amounted to 7.29 t/ha; 2016 was critical with regard to weather conditions – the realization of the biological potential of sorghum plants was significantly lower – at the level 6.33 t/ha; in 2017, the average yield was 7.15 t/ha of grain. Among the hybrids, the least productive was ‘Lan 59’ (5.14 t/ha), and an average yield of ‘Burgo F1’ and ‘Briggo F1’ were 7.57 and 8.06 t/ha, respectively. The maximum yield for all hybrids was formed at the 50-cm row spacing, namely ‘Lan 59’ – 5.40,” ‘Briggo F1’ – 8.48 t/ha and ‘Burgo F1’ – 7.86 t/ha, respectively. With the pre-sowing application of N60 compared to N20, the yield of hybrid ‘Lan 59’ grew by 0.41–0.51 t/ha, ‘Briggo F1’ by 0.27–0.40, ‘Burgo F1’ by 0.22–0.29 t/ha.Conclusions. The biggest share in sorghum yield formation had the ‘hybrid’ factor (43%). ‘Conditions of year’ factor (21%) and ‘dose of nitrogen’ (20%) had an equivalent effect, and ‘inter-row spacing’ factor amounted to 10%. Studies have shown that there is a positive moderate correlation between yield and dose of pre-sowing nitrogen (r = 0.49). Grain sorghum plants react positively to additional nitrogen, what is manifested in increased yields. This dependence can be explained not only by moderate nitrogen application rates but also by the low level of hydrolyzed nitrogen stock in the soil of the experimental plot.