PHOTOSYNTHETIC ACTIVITY OF PROSO MILLET (PANICUM MILIACEUM) CROPS IN THE CRYOLITHOZONE

In the cryolithozone, a study was conducted on the permafrost-affected floodplain soils of the Republic of Sakha (Yakutia) to examine the influence of agricultural practices on the leaf surface development of proso millet (*Panicum miliaceum* L.) cultivated for forage production. The experiments took place from 2024 to 2026 at the training farm of the Oktemtsy branch of the Arctic State Agrotechnological University (Arctic GATU). The research aimed to investigate the patterns of leaf surface development and the efficiency of its activity in millet crops, depending on seeding rates and mineral nutrition. The 'Kulundinskoye' variety of proso millet was studied based on two factors: seeding rates (20, 25, 30, 35, and 40 kg/ha) and application rates of complete mineral fertilizer (NPK) at 60.0, 70, 80, and 90 kg of active ingredient per hectare. It was determined that the maximum leaf surface area for proso millet is achieved at a seeding rate of 30.0 kg/ha; the three-year average for this indicator was 21.5 thousand m²/ha, which is 28.7% higher than the control. Increasing the seeding rate further to 35.0 and 40.0 kg/ha results in a decrease in leaf surface area (to 20.0 and 18.5 thousand m²/ha, respectively). The highest yield of millet forage mass was obtained at a seeding rate of 25.0 kg/ha, reaching 37.3 t/ha—an increase of 10.3% over the control. Applying NPK at a rate of 70.0 kg of active ingredient per hectare results in the largest leaf surface area for the crop (21.4 thousand m²/ha, which is 31.3% higher than the control) and the highest yield of forage biomass for proso millet (43.5 t/ha, 35.9% higher than the control).