Genotyping variability of symbiotic nitrogen fixation ability of Acacia cyanophylla Lindl.

Genotypic variability of the symbiotic nitrogen fixation ability on Acacia cyanophylla Lindl. The phenotypic and functional characteristics of four rh izobium strains isolated from nodules of Acacia cyanophylla Lindl., syn. Ac acia saligna (Labill.) H. Wendl., and the inoculated host-plant genetic var iability were evaluated. The evaluation used permitted the ranking of the t ested rhizobium strains and seedlots according to their performance. The gr owth pattern of these strains indicated that A. cyanophylla was al,le to no dulate and fix N-2 With slow- and fast-growing rhizobium strains. The acety lene reduction activity test reflected a variable effectiveness of the stra ins depending on their site of isolation. Strains RFH383 and RFH483 were mo re effective than RFH183 and RFH283. The high antibiotic resistance acquisi tion by RFH183 and RFH283 strains seemed to be inversely related to their e ffectiveness. Acacia cyanophylla seedlings from five seedlots displayed a h igh variability regarding their growth, nodulation, and ability to fix nitr ogen. The ability to fix nitrogen was greater in the seedlings from KL seed lot than those from EN, KR, and TZ seedlots. The qualitative assessment of the seedlots using correspondence factorial analysis showed that the seedli ngs from KL seedlot preformed better than those from KR and TZ. The seedlin gs from TN and EN seedlots displayed an intermediate behaviour pattern. See d origin seemed to affect the growth, nodulation, and nitrogen fixation of inoculated A. cyanophylla. The behaviour of this species and that of its as sociated rhizobium strains appeared to be very sensitive to variations in s ite characteristics. Results suggested that the association between plants derived from KL seedlot and RFH383 strain may represent the best partnershi p allowing the improvement of symbiotic nitrogen fixation.