Morphophysiological features of the generative offspring of Aesculus hippocastanum L. from various ecologically unfavorable areas of an industrial city

Abstract

The results of the influence of various ecological conditions of an industrial city (environmentally favorable zone, zones of motor vehicle emissions and metallurgical production, damage by the chestnut miner Cameraria ohridella Deschka & Dimič) on the functional state of the generative offspring of Aesculus hippocastanum L. were given. The average degree of the mass variability of the horse chestnut seeds was revealed, the level of which depended on the type of pollution. Higher values of the variation coefficient were established in seeds from monitoring sites ecologically unfavorable for plant growth. A decrease in the mass of ripe seeds of horse chestnut exposed to the effects of vehicle emissions, metallurgical production, and the severe attack of the chestnut moth C. ohridella was shown compared to samples from an ecologically favorable zone. It was found that the moisture loss in seeds from the ecologically favorable zone was on average 25.0 %, while from the main road zone – 15.2 %. A decrease in the content of storage proteins by an average of 14.5 % in the zones of anthropogenic pollution was observed. The largest values of this characteristics were shown by most trees from the ecologically favorable zone. In the seeds of A. hippocastanum plants, an increase in the activity of both benzidine peroxidase and catalase was established mainly under the effects of aerotechnogenic pollution. The level of enzyme activity depended on the type of phytotoxic emissions. A decrease in the activity of benzidine peroxidase was registered due to the effects of motor vehicle emissions, and an increase due to the effects of metallurgical production. A significant increase in catalase activity was found in the seeds of A. hippocastanum trees from two monitoring sites and, especially, under the influence of vehicle emissions, which can be explained by a compensatory reaction in response to reduced peroxidase activity. An individual reaction of the studied protein system (storage proteins, antioxidant enzymes) of the seeds of some trees was observed, regardless of the stress level of technogenic load and the type of pollutants. At each monitoring site, trees whose seeds had both increased and significantly decreased enzyme activity were identified. In the Botanical Garden and in the park near the metallurgical enterprise, the seeds of only one of three trees showed high activity of both peroxidase and catalase. Considering the physiological functions of the studied enzymes in the seeds and the reaction of the plant organism to biotic and abiotic stresses, the increase in the activation of catalase and peroxidase indicated their participation in antioxidant protection against active forms of oxygen to ensure a reduction in the intensity of damage processes in the generative offspring of A. hippocastanum L. The variability of the level of enzyme activity in horse chestnut seeds means adaptation to environmental conditions and, in general, reveals the adaptive ability of generative offspring to germinate due to the high antioxidant potential to counteract the development of oxidative stress under the influence of adverse environmental factors. It was concluded that the chronic influence of adverse factors of the urban environment causes the formation of individual seeds with increased antioxidant protection characteristics, which can be used as planting material when creating sustainable plantations in an industrial city.