Yield and Quality Attributes of Nasturtium as Affected by Nitrogen and Sulfur Supply

Two field experiments were conducted during two successive seasons to evaluate growth and glucotropaeolin content of nasturtium (Tropaeolum majus) under different levels of nitrogen and sulur supply. Three nitrogen rates (0, 60 and 120 kg N ha-1) as ammonium nitrate and three sulfur rates (0, 50 and 100 kg S ha-1) as elemental sulfur were used. Results indicated that nitrogen and sulfur supply increased biomass accumulation of T. majus including plant height, branches number, plant fresh weight, leaf fresh and dry weights, and stem fresh and dry weights. The highest values of growth traits were recorded with the highest nitrogen rate (120 kg ha-1) and the medium or the highest sulfur rate (50 and 100 kg S ha-1) at all growth stages in both seasons. Glucotropaeolin content ranged from 23.45 to 45.26 μmol g-1 DW in leaves and from 117.92 to 156.31 μmol g-1 DW in seeds. The response of glucotropaeolin content to nitrogen supply varied between plant parts and growth stages. Glucotropaeolin content in seeds was unaffected by nitrogen supply. The highest glucotropaeolin content in leaves was found in plants that received 120 kg N ha-1. Glucotropaeolin content in leaves and seeds significantly increased with sulfur supply in both seasons at all growth stages.