Photosynthesis Parameters and Productivity of Crambe abyssinica when Using Growth Regulators

The study was conducted in order to assess the formation of photosynthetic activity of Crambe abyssinica and its productivity depending on foliar feeding with growth regulators to optimize the elements of crop agrotechnology in the forest-steppe conditions of the Middle Volga region. The experimental work was carried out in 2021–2023. The material for the study was Crambe abyssinica of the Demetra variety. The experimental design included the following options: control (no treatment); foliar treatment with the Blackjack, K/Na Humate, Zircon, and Albit preparations in the doses recommended by manufacturers. Spraying of vegetative plants was carried out at the beginning of budding of the crop. The use of growth regulators contributed to an increase in the assimilation surface area by 6200–8900 m²/ha, photosynthetic potential by 300–500 m² day/ha, net productivity of photosynthesis by 0.3–1.5 g/m² day, and leaf area index by 0.17–0.35 compared to the control. The largest leaf area was formed in the variants with foliar treatment with the Blackjack and K/Na Humate regulators (69 100 and 70 300 m²/ha, respectively). The highest value of photosynthetic potential was noted in the variant with the use of K/Na Humate (3.40 million m²/ha day). The highest net photosynthetic productivity (4.95 g/m² day) was observed when treated with Zircon. The utilization rate of photosynthetically active radiation (PAR) by the Crambe plants was 1.28–1.78% depending on the preparations used, with the value of this indicator in the control of 1.16%. The average Crambe yield for 2021–2023 was 1.69–1.98 t/ha. The use of growth regulators contributed to its significant increase, the increase was 0.21–0.29 t/ha. The most effective preparations were Zircon and Blackjack, the use of which ensured the formation of the highest seed yield: 1.98 and 1.94 t/ha, respectively.