Bioassay of phytotoxicity of soils in Yakutsk using oat (Avena sativa L.) as test-object

Abstract

A bioassay of 63 samples of soil collected in the territory of Yakutsk and one control sample from an undisturbed biotope has been performed. Seeds of the oat cultivar «Pokrovskii» were germinated on aqueous extract and on soil. Germination capacity and development of seedling shoot and root were estimated separately on the 3rd, 4th, and 14th days; toxicity value (TV) was calculated. High figures of germination capacity and development of shoot and root were registered in the control sample. The soils from the city are characterized by high variability of all parameters. With the aqueous extract we observed inhibition of germination capacity of up to 72 % on the third day, up to 44 % on the fourth day, and in case of the contact bioassay (i.e. using soil per se) in some samples 100 % inhibition was observed. Inhibition of development of vegetative organs is less pronounced, and with aqueous extract in 30 % of the samples we registered stimulating effect. Average TV in the territory of the city (calculated using 9 parameters) was 0.73, which is a low level of phytotoxicity. In individual sites it varied between the normal level (no toxic effect) and high toxicity. Most examined sites in the territory of Yakutsk were characterized by average or low phytotoxicity of soil. Relatively high toxicity was registered in sites with high traffic load and on the streets open for truck transport. A statistically significant correlation between the analyzed parameters of the oat and intensity of traffic load was found, and it was more pronounced with the contact bioassay. The contact bioassay results in higher values of inhibition of the analyzed parameters and produces higher TV, which indicates the presence of pollutants that are absent from the water fraction but have a negative impact on germination capacity and development of seedlings.