Productivity of common Saint-John's wort (Hypericum perforatum L.) by using transplant reproduction method in the conditions of drip irrigation

The influence of plant nutrition area and mineral fertilizer rates on the productivity of St. John's wort (Hypericum perforatum L.) by using transplant reproduction method in the conditions of drip irrigation was studied. It was proved that the transplant method of cultivation of St. John's wort under drip irrigation is a very effective method of reproduction of this crop. Four variants of  planting density per unit area were studied: 42 thousand plants / ha (cultivation scheme 60x40 cm), 56 thousand plants / ha (60x30 cm), 83 thousand plants / ha (60x20 cm) and 167 thousand plants / ha (60x10 cm). Yield recording of raw materials (air-dry tops) was carried out in the phase of mass flowering. In the first year of vegetation this period was in the first decade of August, in the second year – in the second decade of June. It was found that the increase in the number of planted plants of St. John's wort per 1 ha contributed to the increased plantation productivity. When having a cultivation plant density of 42,000 plants / ha, the yield of dry grass in the first year of vegetation was 3,02 t / ha. Increasing the number of plants to 56 thousand plants / ha provided 3,26 t / ha of raw materials. The highest yield of dried St. John's wort – 3,76 t / ha in the first year of vegetation was obtained in the variant with the largest number of planted plants per unit area - 167 thousand plants / ha. In the second year of vegetation of St. John's wort in the variant with the lowest plant density of 42 thousand plants / ha, the yield was 3,65 t / ha. The most productive plantation of the second year of vegetation was in the variant with a plant density of 83 thousand plants / ha, where the yield of dry raw materials was 3,96 t / ha. A further increase in the number of plants per unit area led to a decrease in crop yields. The influence of four variants of the main application of mineral fertilizers on the productivity of St. John's wort was also studied: N0P0K0 (reference), N60P60K60, N120P120K120 and N180P180K180. It was found that with increasing fertilizer application rate, the yield of dry raw materials increased. The most favorable conditions for growth and development of plants of St. John's wort developed in the variant with the maximum rate of fertilizer application - N180P180K180, where the yield of dry raw materials in the first year was 3,31 t / ha, and in the second year – 4,15 t / ha, which exceeded the reference result (without fertilizers) by 0,61 t / ha and 0,84 t / ha, respectively.