The effect of Frankia isolates from Comptoniaperegrina and Alnuscrispa on the growth of Alnusglutinosa, A. cordata, and A. incana clones

Abstract

Three Alnus clones, one each of A. glutinosa (L.) Gaertn., A. cordata (Lois.) Desg., and A. incana (L.) Ait., were inoculated with Frankia isolates from root nodules of Comptoniaperegrina (L.) Coult. and A. crispa var. mollis Fern. Both Frankia isolate and Alnus clone contributed significantly to postinoculation height and diameter growth of plants in nitrogen-free culture, while interaction between isolate and clone was not statistically significant (α = 0.05). All combinations of host plants and isolates yielded nodules that were effective in fixing nitrogen as evidenced by the ability of nodules to reduce acetylene to ethylene. Alnus plants inoculated with the Comptonia isolate grew in height at a rate 1.9 times that of Alnus plants inoculated with the A. crispa isolate, while more than doubling the stem diameter growth increment of plants inoculated with the A. crispa isolate. The A. glutinosa clone grew at least four times as rapidly in height and at least twice as rapidly in diameter as the other two Alnus clones after inoculation with Frankia isolates. Results indicate that potential exists for the improvement of growth rates of Alnus and other Frankia-nodulated plants by selection of both Frankia isolates and host plant genotypes for specific environments.