Impact of exogenous growth regulators on growth and photosynthetic activity in dwarf mandarin plants (Citrus unshiu Marc.)

Abstract

The impact of synthetic regulators on the growth and development of mandarin plants was investigated. It was shown that the exposure of plants to growth regulators had no effect on leaf chlorophyll content. Non-root application of nanoelicitor and siliplant synthetic regulators elevated the carotenoid content to 2.69-3.11 mg/g (control, water: 2.57 mg/g) and stimulated protective response. The total chlorophyll- carotenoid ratio in plants treated with nanoelicitor (4.29 mg/g) and siliplant (4.12 mg/g) was less than in the control, reflecting the degree of plant adaptation to adverse conditions in the growing season. Exposure to growth regulators improved photosynthetic activity and overall functionality. Chlorophyll fluorescence assays were used to evaluate photosynthetic activity coefficient as falling within a range of 0.54-0.57, which exceeded the control by 1.2-fold. Nanoelicitor was shown to induce active shooting and reduce fruit shedding. Compared to the control, growth regulators increased the retained fruit value by 1.5-1.9-fold and improved plantation productivity. Phytoregulators have shown promise in both improving the functional condition and reducing preharvest shedding in dwarf mandarin plants.