ROOT HAIRS AND PLANT GROWTH ATLOW NITROGEN AVAILABILITIES

Abstract

Four grass species, Holcus lanatus L., Deschampsia ftexuosa (L.) Trin., Poa annua L. and Lolium perenne L. cv. S.23 and cv. ‘Norlea’ were grown for 28 d in continuous flow nutrient solution containing nitrogen (N) at one of three concentrations (0.02, 0.21 or 4.0 mol m−3) as nitrate or ammonium. Growth, N uptake and root hair production were measured. Root hair growth in D. flexuosa and P. annua was the most responsive to low N availability. These responses were generally greater to ammonium than nitrate. The possible effects of the absence of root hairs on growth were tested via empirical relationships between relative growth rates and N inflow rates to estimate the contributions made to growth by root hairs. Only in D. flexuosa at the lowest N concentration were significant contributions found. Nitrate and ammonium had no differential effect in this respect. Copyright © 1987, Wiley Blackwell. All rights reserved