The content of dry matter and chlorophylls in paulownia plants of different ages in the Right Bank Forest Steppe of Ukraine

Abstract

Purpose. To determine the influence of the main fertilization, the application of cryoprotectant and foliar feeding on the formation of the content of dry matter and chlorophylls a and b in paulownia plantations of different ages. Methods. The research was carried out in 2021–2023 at the experimental plot of the Bila Tserkva National Agrarian University located in the forest plantations in the Right Bank Forest Steppe of Ukraine (Kyiv region). Design of the experiment: factor A – fertilization: 1) without fertilizers, 2) application of organic fertilizer Vermykompost (400 kg/ha) before planting; factor B – application of cryoprotectant: 1) without cryoprotectant, 2) cryoprotectant Mars-EL (0.5 l/ha) applied at the beginning of leaf growth; factor B – foliar application of fertilizers: 1) no treatment, 2) Quantum-AmiNoFrost (1.5 l/ha), 3) SmartGrow Recovery (2.0 l/ha). Results. In the first year of vegetation in the flowering phase, the average content of dry matter of paulownia plants was 44.8%, chlorophylls a and b – 2.6 and 1.5 mg/kg, and in the control treatment – 43.6%, 2.14 and 1.43 mg/kg, respectively. According to the experiment, the highest indicators were obtained in the treatment of fertilizing plantations with organic fertilizer Vermykompost, as well as cryoprotectant Mars-EL and foliar application of anti-stressors Quantum-AminoFrost or SmartGrow Recovery: dry matter content – 46.4 and 46.9%, chlorophyll a – 2.80 and 2.89 mg/kg, chlorophyll b – 1.59 and 1.65 mg/kg, respectively. In the 2-year-old plantations, the average content of dry matter in the treatments was 45.7%, chlorophylls a and b – 2.74 and 1.54 mg/kg, while in the control treatment these indicators were significantly lower: 45.2%, 2.24 and 1.24 mg/kg, respectively. As in the previous year, the maximum contents of dry matter (46.2–46.3%) and photosynthetic pigments (chlorophyll a: 2.89–3.01 mg/kg, chlorophyll b: 1.66–1.70 mg/kg) obtained for combinations of all three factors of the experiment. In the third year of vegetation of paulownia plantations in the flowering phase, on the average, the stems contained 51.2% of dry matter; the content of chlorophyll a in the leaves was 3.95 mg/kg, chlorophyll b – 2.84 mg/kg, in the control variant – 49.7%, 3.71 and 2.51 mg/kg, respectively. The highest results according to the experiment, as in the previous two years, were recorded in the treatment with the complex application of organic fertilizer Vermykompost, cryoprotectant Mars-EL and Quantum-AminoFrost or SmartGrow Recovery: the content of dry matter was 52.5–52.7%, chlorophyll a 4.05–4.07 mg/kg, and chlorophyll b 2.84–2.89 mg/kg. Conclusions. The parameters of the formation of indicators of the content of dry matter and photosynthetic pigments in paulownia plants were largely determined by the agrotechnical measures applied in the experiment, namely, the introduction of the main fertilizer and the treatment of plants during the growing season with cryoprotectant and anti-stress formulations, as well as the age of the plants. In particular, in the first two years of vegetation, the contents of dry matter and chlorophylls a and b were approximately at the same level in the experimental treatments, while in the third year, as the plants developed, they increased significantly. Throughout all the years of the study, the highest indicators of the content of dry matter and photosynthetic pigments were recorded in the treatments with the complex application of all three studied factors: fertilizer, cryoprotectant and foliar feeding.