Knowing whether leguminous trees have thepotential tonodulate after infec tion by rhizobial bacteria is important for managing nitrogen (N) applications during tree production and for culture inthe landscape. Although 98% ofstudied species inthePapilionoideae nodulate, thenodulation status oftwo tree species inthissubfamily isuncertain. Cladrastis kentukea (Dum.-Cours.) Rudd (Ameri can yellowwood) did not form nodules during inoculation studies in1939 and 1992. Nodules were observed on mature Sophora japonica L (Japanese pagodatree) inJapan andHawaii inthe1940s, butcompatible rhizobia reportedly isolated inJapan arenolonger held inbacterial collections. Our objective was to verify further that American yellowwood does not nodulate and toconfirm reports that Japanese pagodatree does nodulate. Rhizobia that infect many plant hosts, soil samples and rhizobial isolates from other Sophora spp., and soil samples from mature American yellowwood and Japanese pagodatreewere used toinocu late 5-day-old seedlings ofAmerican yellowwood, Japanese pagodatree, and control species. Soil from indigenous and introduced trees inthe continental United States, Hawaii, Japan, and China was used. Inoculated and uninoculated plants were grown for 7 weeks insterile Leonard jars orclay pots containing perlite and irrigated with sterile, N-free Hoagland's solution. No inoculation treat ment elicited nodulation of American yellowwood orJapanese pagodatree. Our results provide additional evidence that American yellowwood lacks that capacity tonodulate and castfurther doubt onnodulation ofJapanese pagodatree.
Source: • HortScience Program Abstract Volume 32,#3
Keywords: leguminous trees EPapilionoideae nodulate Nodules nitrogen (N) applications infect