Dynamics of change of leaf attributes of Brussels sprouts in response to switches between high and low supply of nitrogen

Abstract

In previous research nitrogen supply was shown to affect several components of foliar growth and development of Brussels sprouts (Brassica oleracea L. var. gemmifera DC.). This paper extends the analysis of data on Brussels sprouts and focuses on the dynamics of change in components of leaf growth and nitrogen concentrations upon change in nitrogen supply. Four treatments were compared: a control without nitrogen limitation, a continuously nitrogen-deficient control, and two treatments with a switch from limiting supply to non-limiting supply or vice versa. Plant nitrogen concentrations changed first and fast upon change in soil nitrogen regime. Upon increase in supply rate, nitrogen concentration also increased in leaves that had completed their expansion. Changes in leaf growth started about 15 days after the switch in nitrogen regime. Leaves that were expanding at the switch responded by an increase in area when nitrogen supply became larger without a change in mass, i.e. specific leaf area increased. Areas of leaves as well as specific leaf area of expanding leaves decreased when the nitrogen supply became smaller. Control of leaf size during initiation and expansion is discussed.