Fig. 2. Effect of CO2 {ambient CO2. a p p r o x i m a t e l y 4 0 0 p , m o l m o l - ' , a n d elevated
CO2, 7 0 0 ( i m o l m o l - ' ) and i n c r e a s i n g doses of NH4NO3 (0, 10 a n d 1 5 m M ) o n N
leaf c o n c e n t r a t i o n (gm~^) of n o d u l a t e d a l f a l f a at t h e age of 4 4 (A, c o r r e s p o n d i ng
to 2 weeks of treatment) and 6 0 days (B. c o r r e s p o n d i n g to 4 w e e k s of treatment).
Bars represent the m e a n i S E ; n - 4 . Bars w i t h the s a m e l e t t e r are not s i g n i f i c a n t ly
different (P> 0.05) a c c o r d i n g LSD test