Photosynthetic productivity of grain sorghum hybrids depending on different forms and doses of fertilisers

The research relevance of the photosynthetic productivity of sorghum hybrids is determined by the need to optimise fertilisation to increase yields in the forest steppe of Ukraine. The study aimed to investigate the effect of complex granular mineral fertilisers on grain yield formation, specifically the photosynthetic productivity of grain sorghum plants. The research was conducted in 2021, 2023-2024 in the experimental field of the State Biotechnological University. The experiment was conducted using the method of systematic repetitions with three times repeatability to ensure the reliability and validity of the results. Sowing was conducted at a ten-centimetre soil layer temperature of 10-12 °C with a sowing rate of 200 thousand seeds/ha using a wide-row method with a row spacing of 45 cm. Leaf surface area and net photosynthetic productivity were determined by the method of A.A. Nichiporovich. The study determined that the maximum possible leaf area per plant and hectare of sowing is formed by plants of the Aggil hybrid under the variant of fertiliser application Dura SOP at a dose of 80 kg/ha and Renovation Fuerza at doses of 80 and 100 kg, and plants of the Brigga hybrid under the variant of fertiliser application Renovation Fuerza at both doses. The photosynthetic productivity of both hybrids increased under the variant of application of all forms and doses of fertilisers compared to the absolute control. The net photosynthetic productivity was the highest in both studied hybrids under the variant of application of Renovation Fuerza mineral fertiliser in doses of 80 and 100 kg/ha. A linear correlation was established, and the regression equation between leaf area and net photosynthetic productivity for both studied hybrids is as follows: y = 0.0479x-0.098 (R2=0.88). The results can be used to optimise the mineral fertilisation of sorghum hybrids to increase yields and reduce costs in the forest-steppe of Ukraine