Influence of organic and conventional farming on seed yield, fatty acid composition and tocopherols of Perilla

Consumer's interest in organic farming is increasing due to the high request of healthier and more nutritious foods in national and international markets. Seed of perilla ('Perilla frutescens' L. Britt.) is an important source of unsaturated lipids and tocopherols. During 2005 growing season, perilla plants were grown under conventional and organic farming in a typical Mediterranean area such as Southern Italy, aiming to evaluate the biomass production and partitioning, seed yield, tocopherol content and fatty acid composition. Organic farming caused a 27% seed yield reduction when compared to conventional farming. The seeds of perilla produced 37% oil on average. Irrespective of the farming systems, the C 18 family, in particular in a-linolenic acid (C 18:3), had the predominant fatty acid in seeds, representing 62% of the total fatty acids in the lipid fraction. No differences were recorded among treatments for the content of plamitic C16:0 (avg. 6.0%), stearic C18:0 (avg. 1.0%), and oleic C18:1 (avg. 14.0%), and linoleic acid (avg. 15.0%). No significant differences were observed between conventional and organic farming on alpha-tocopherol (avg. 9.2 mg kg-1), and beta+gamma-tocopherol (avg. 565.9 mg kg-1), whereas the delta-tocopherol was not detected. In summary, it has been possible to produce high quality seeds of perilla under both conventional and organic farming. Improvement in management techniques and cultivation factors are highly needed to fill the gap between organic and conventional yields and also to enhance and standardize the quality of organic products.