Nitrate reductase activity of nonmycorrhizal Douglas-fir rootlets and of some associated mycorrhizal fungi

Douglas-fir root tips reduced nitrate at much higher rates than seven mycorrhizal fungi, which also differed between species in rate of nitrate reduction. Results are related to nitrogen nutrition of Douglas-fir.Excised, nonmycorrhizal root tips of Douglas-fir reduced nitrate at much higher rates than seven mycorrhizal fungi commonly associated with Douglas-fir. The fungi differed significantly in degree of activity:Cenococcum geophilum, Piloderma bicolor, andRhizopogon vinicolor were highest;Amanita muscaria was intermediate; andHebeloma crustuliniforme, Thelephora terrestris, andLaccaria laccata were lowest.