Productivity of sorghum [Sorghum bicolor (L.) Moench] and soryz (S. orysoidum) depending on methods of weed control

Purpose. To establish the effectiveness of methods of controlling the number of weeds on the energy productivity of sorghum and soryz in the conditions of unstable moisture in the western part of the forest­steppe of Ukraine. Methods. Field, laboratory, mathematical and statistical methods were used in the experiments. Thus, field research consists of studying the biological and ecological characteristics of growth, productivity and quality of the crop, including observation, recording of conditions and results. The purpose of the laboratory method is to identify the relationship between the plant and the environment (soil) through their analysis. Mathematical and statistical methods are used to process experimental data in order to increase the validity of the results. Results. Over the years of research, the species and quantitative composition of weeds in crops of sorghum and soryz was established. The highest efficiency of weed control was observed in the variant with manual wee­ding – 95.0–97.0%, with chemical treatment – 82.0–83.0%, with mechanical treatment – 78.6–88.5%. On the other hand, in the control variant (no maintenance), weediness increased by 10.3–13.9%. The lowest grain and biomass yields in the varieties ‘Dniprovskyi 39’ (2.35 and 22.23 t/ha) and ‘Samaran 6’ (2.50 and 22.7 t/ha) were obtained in the weeded variant (control); slightly higher for the mechanical treatment. The use of a chemical control method helped to increase the yield to 3.40 t/ha of grain and 29.07 t/ha of biomass in sorghum and 2.80 t/ha of grain and 27.73 t/ha of biomass in soryz; manual weeding – up to 3.90 t/ha of grain and 32.13 t/ha of biomass in sorghum and 3.50 t/ha of grain and 30.63 t/ha of biomass in soriz. Conclusions. The highest estimated yields of bioethanol and solid biofuel per unit area were obtained by manual weeding in the cultivation of sorghum (1.29 and 9.16 t/ha) and soryz (1.16 and 9.09 t/ha). The total energy output was 181.62 and 177.02 GJ/ha respectively. In other versions of the experiment, the noted indicators were lower. Correlation regression analysis of the data showed a strong correlation between grain productivity and bioethanol output, solid biofuel yield and output, grain productivity and energy output from bioethanol, biomass yield and energy output from solid biofuel. The correlation coefficient ranged from 0.87 to 0.99 and the coefficient of determination ranged from 0.78 to 0.99.