Ecological and physiological investigations on Eichhornia crassipes (MART.) SOLMS. 1. The effect of different environmental conditions on the development of root colour

Thecellwallsof!'. crassipesrootsshowareasof strongcoloration,whichcanrangefromlight brown through brown, blue, violet to blue-black, whiie the plants appear generally healthy' This work describes the environmental factors which control the particularly noticeable blue colouration of the roots. From studies conducted under defined conditions in growth chambers, substrate nitrogen deficiency in the light produces an intense blue root coiouration. Thus with nitlate or ammonium deficiencyof thenutrientmediumE. crassipes canbeconsideredanitrogenmonitor.