Effects of Nitrogen Sources and Levels on Growth and Alkaloid Content of Periwinkle

摘要

The main aim of this study was the evaluation of the effects of nitrogen sources on growth of the Catharanthus roseus and the concentration of total alkaloids, vincristin and vinblastin. Plants raised in sand culture in greenhouse and irrigated two times per day with Hoagland solution containing nitrate, ammonium and nitrate plus ammonium as the nitrogen source and at total nitrogen concentrations of 2.75, 5.5, 11, 22 and 32 mM. Plants fed with nitrate plus ammonium showed the greatest increase in shoot dry mass whereas the lowest shoots and total dry mass were exhibited in nitrate treatment. There was no significant difference in shoot or root dry mass between plants fed with different nitrogen concentrations at the 5% probability level but the highest total dry mass was observed in 22 mM nitrogen concentration. The highest content of amino acid s, proteins, total nitrogen, total alkaloids, vincristin and vinblastin were observed in plant fed with nitrate plus ammonium. Maximal contents of amino acid s, total alkaloids, vincristin and vinblastin occurred at a total nitrogen concentration of 11 mM. Significant correlation was found between vincristin and vinblastin content and total alkaloids, protein and nitrogen. Increase in the nitrogen level beyond 11 mM had an antagonistic effect on alkaloid content. The increase in plant mass was not related to alkaloid levels and maximum the alkaloid production occurred at 11 mM nitrate plus ammonium.