The impact of agricultural activity on soil phytotoxicity: The choice of bioindicators

Background. The study is devoted to the assessment of phytotoxicity of soils affected by agricultural activities by the method of bioindication. The main objective is to select the most sensitive bioindicator for the determination of phytotoxicity in agricultural soils. It was found that cruciferous crops, Brassica napus (rapeseed), Lepidium sativum (watercress), are the most sensitive to contamination, demonstrating a decrease in germination to 24% and phytomass to 0.13-0.62 g, while barley showed a germination resistance of 70-100%. Cases of latent phytotoxicity have been identified with preserved germination, but inhibition of root growth. The results confirm the effectiveness of the method and the need for an integrated approach using several bioindicators.

Purpose. The purpose of this study is to select the most sensitive bioindicator for determining the phytotoxicity of agricultural soils.

Materials and methods. To assess the phytotoxicity of soils, samples were taken from the DSTU training ground. The main series included 4 arable samples (n=4), selected by the envelope method from a depth of 0-20 cm according to GOST 17.4.4.02-2017. The control sample was taken from the adjacent forest belt (n=1). Each combined sample weighing 1 kg was formed from 5-point samples. Four test crops were used: radish (Raphanus sativus L.), barley (Hordeum vulgare L.), rapeseed (Brassica napus L.) and watercress (Lepidium sativum L.). 3 analytical replications in Petri dishes were prepared for each sample and culture. Incubation was carried out for 10 days. The following parameters were evaluated: germination (%), germination energy (%), length of shoots and roots (mm), crude phytomass (g). Statistical data processing was performed with the calculation of average values and standard deviation for each sample and test culture.

Results. The results have shown a significant inhibition of the test plant growth in contaminated samples, which resulted in a decrease in key indicators by 24-92% compared with the control. Cruciferous crops (rapeseed and watercress) showed the greatest sensitivity, with a sharp decrease in germination to 24%, germination energy to 1.0, and phytomass to 0.13-0.62 g. At the same time, barley has demonstrated relative stability, maintaining germination at the level of 70-100%, which confirms the need to use several bioindicators for a comprehensive assessment.

Conclusion. During the study, it was found that agricultural activity in the field under study led to the formation of phytotoxicity of the soil, manifested in the suppression of sensitive cruciferous crops (rapeseed, watercress) and the radish root system. Rapeseed and watercress are highly sensitive bioindicators for monitoring. The revealed heterogeneity of phytotoxicity requires a differentiated approach to assessing soil conditions. The conducted studies have demonstrated the effectiveness of the phytoindication method for assessing the phytotoxicity of soils exposed to agrogenic effects.