DEVELOPMENT AND PRODUCTION OF FRESH AND DRIED LEAF BIOMASS OF LEMON BALM (Melissa officinalis L.) UNDER ORGANIC FERTILIZERS TREATMENT

The study was conducted at the Demonstration Center for Organic Agriculture at the Agricultural University - Plovdiv, Bulgaria during the 2015-2018 period A field trial has been set up in three replications with a plot size of 25 m 2 in Lemon balm (Melissa officinalis L). The aim is to determine the impact of Amalgerol, Lithovit and Tryven organic fertilizers on the growth, development and productivity ofLemon balm. The treatment with the organic fertilizers leads to an increase in values of the researched indicators. Fresh biomass weight when treated with Tryven goes to 250.05 g, when the control variant is only 143 g. Fresh leafs weight reaches higher values at all fertilized variants. Amalgerol treatment leads to - 31.07 g for dry leafs weight and Ttyven to 37.72 g. compared to the non treated variant - 22.73 g. Statistically proven - highest yield of green fresh biomass was obtained in the variants treated with Ttyven - 989.2 kg/da (7.5% above the control) and Amalgerol - 980 kg/da (6.5% above control), respectively. The yield of the fresh leafs increase with 21.1% compared to the control (up to 541.6 kg/da) when treated with Lithovit and 12.3% (to 502.2 kg/da) when treated with Amalgerol. Highest city leafs yield was obtained when Tryven was applied - 149.2 kg/da (2.1% above the control).