Effects of nitrogen on development and growth of the leaves of vegetables. 1. Appearance, expansion growth and life span of leaves of Brussels sprouts plants

In greenhouse pot trials, Brussels sprouts cv. Icarus SG2004 plants were supplied with various amounts of N at different stages during growth. The rate of leaf emergence ranged from 0.39 to 0.72 per day and was significantly increased by increasing N application rate. Leaf expansion rate and mature leaf area increased with leaf number, reaching maximum values between leaf number 10 and 20 and decreasing subsequently. Plants receiving more N had a higher total green leaf area per plant, due to more and larger green leaves. Specific leaf area of all leaves declined gradually from 130-230 cmsuperscript 2/g (depending on experiment) at about 30 days after planting to 60 cmsuperscript 2/g at the end of the experiments and was usually significantly increased by increasing N application rate.