Abstract

The effects of different months of the year and nitrogen sources on garden cress (Lepidium sativum L.) yield, quality and nitrate accumulation were investigated during the years 2002 and 2003. In both years, seeds were sown on the first days of September, October, November, January, February and March. Three different nitrogen sources were used: Farmyard (cattle) manure (100 ton·ha^-1), Ca(NO₃)₂-15.5% N (150 kg N·ha^-1) and (NH₄)₂SO₄)-21% N (150 kg N·ha^-1). Yield, leaf color, dry matter, vitamin C, total glucosinolate content and nitrate accumulation were assessed. No interaction between sowing date and nitrogen form was observed for any of the assessed parameters. Growing period affected all parameters significantly. Plants obtained from January and February sowings resulted in better yield, leaf color, dry matter and vitamin C content. But the nitrate contents also increased. Highest total glucosinolate content was observed during the warmer months. Nitrate nitrogen application increased yield, leaf greenness, vitamin C and nitrate content while farmyard manure application raised dry matter and total glucosinolate contents. Nitrate content of the garden cress plants did not exceed 391 mg kg^-1 fresh weight, which is below the accepted daily intake of 3.7 mg nitrate per kg^-1 bodyweight set by European Commission’s Scientific Committee on Food.

Key words: Lepidium sativum L., farmyard manure, nitrate, glucosinolate, vitamin C.