The dissertation is devoted to the study of the accumulation of lead, cadmium, zinc, copper by the vegetative mass and seeds of milk thistle (Silybum marianum L.) and the effectiveness of phytoremediation for its cultivation in field crop rotations with the use of various types of fertilizers under conditions of intensive agriculture of the Right-Bank Forest-Steppe of Ukraine.
The intensity of accumulation of heavy metals in the vegetative mass and seeds of milk thistle under its mineral, organic and foliar fertilisation in the conditions of intensive farming was improved.
The research on the topic of the dissertation was carried out during 2017-2020 on grey forest soils in the conditions of the Right-Bank Forest-Steppe in Vinnytsia region.
It was found that when growing milk thistle under intensive farming conditions, the MPC of lead, cadmium, zinc and copper in its vegetative mass and seeds was exceeded, and the intensity of accumulation of these metals in the vegetative mass and seeds of milk thistle depended on the level of soil contamination with these elements.
It was found that fertilisation of soils and foliar feeding in the cultivation of milk thistle increased the yield of vegetative mass and the number of seeds in an increasing sequence: mineral fertilisers, organic fertilisers and foliar feeding. Soil fertilisation with mineral fertilisers (ammonium nitrate, simple superphosphate, potassium chloride, NPK fertiliser mixture) contributed to higher removal of lead with the vegetative mass and seeds of milk thistle – from 52,2% to 2,14 times, cadmium – from 41,9% to 3,5 times, zinc – from 20,1% to 2,6 times and copper – from 10,2% to 2,3 times compared to the variant without fertilisation.
It was found that the highest removal of heavy metals (lead, cadmium, zinc and copper) was observed when fertilizing soils with nitrogen fertilizers, and fertilizing soils with organic fertilizers (humus green manure and green manure) increased the removal of lead from the soil by milk thistle – from 3,9% to 42%, cadmium – from 3,2% to 58%, zinc – from 13,6% to 2,03 times and copper – from 24,5% to 60,7% compared to the variant without fertilisation.
It was found that foliar fertilisation of milk thistle (Growth concentrate, Potassium chelate and Phosphorus chelate) increased the removal of lead from the soil by 11,7% to 69,7 times, cadmium by 0,6% to 2,1 times, zinc by 6,3% to 45,5% and copper by 10% to 38,3% compared to the variant without fertilisation.
When fertilising soils with mineral (N60P60K60), organic (humus, defecate, mustard) fertilisers and foliar feeding (Phosphorus-chelate, Potassium-chelate, Growth-concentrate), the highest yield of milk thistle seeds was observed when using mineral fertilisers (N60P60K60). It was found that the lowest coefficient of accumulation of heavy metals in milk thistle seeds under fertilisation of soils with mineral fertilisers was observed when using a mixture of fertilisers N60P60K60 (ammonium nitrate, simple superphosphate, potassium chloride).
It has been determined that fertilisation of soils in milk thistle cultivation with organic (humus, defecate) and green (green manure) fertilisers increases the coefficient of accumulation of lead, cadmium, zinc and copper in its vegetative mass and seeds. The lowest rate of heavy metal accumulation coefficient was observed when growing milk thistle after green manure (mustard).
It was found that the lowest coefficient of accumulation of heavy metals in milk thistle seeds was observed when using Potassium chelate and zinc – Phosphorus chelate.
