Symbiotic efficiency, biosorption and the growth of rhizobia on Horse gram plants under aluminium stress | Učinkovitost simbioze, biosorpcije in rasti rizobijev pri vrsti Macrotyloma uniflorum zaradi aluminijevega stresa

English. The aim of the present study was to evaluate the tolerance potential of Horse gram rhizobia to aluminium (Al) toxicity, the enhancement in pod formation, symbiotic efficiency and biosorption potential in the rhizobia inoculated Horse gram (Macrotyloma uniflorum (Lam.) Verdc.) plants. Initially, 32 isolates of Horse gram rhizobia were screened for their tolerance of Al in growth media. Among the 32 strains, HGR 4, 6, 13 and 25 that were more tolerant were inoculated individually to Horse gram plants and the plants were then screened for the ability of pod formation, symbiotic efficiency and biosorption potential. Among them, maximum pod formation was observed in Horse gram upon inoculation with HGR-6 and grown at 400 µg g-1 of Al. Maximum nodulation was observed in Horse gram upon inoculation with HGR-6 and HGR-13 grown at 200 µg g-1 Al. Leghaemoglobin content was maximumon inoculation with HGR-13 at 400 µg g-1 of Al. The strain HGR-13 has shown biosorption potential in soil and as well as in root nodules even at 300 µg g-1 of Al though it was maximum at 100 µg g-1. This study demonstrated that the Horse gram plantsinoculated with Rhizobium strains HGR - 4, 6, 13 and 25, besides having nitrogen fixing ability also have the ability to grow in Al contaminated soils. Hence, Horse gram plants associated with these strains of rhizobia could be used in phytoremediation ofmetal (Al) contaminated soils.

Slovenian. Namen študije je bil ovrednostiti tolerančni potencial rizobijev za aluminij pri vrsti Macrotyloma uniflorum (Lam.) Verdc. Preučevali smo tvorbo strokov, učinkovitost simbioze in biosorpcijski potencial 32 izolatov rizobijev. Med njimi so bili najbolj tolerantni sevi HGR 4, 6, 13 in 25, ki smo jih v nadaljevanju inokulirali individualno na rastline in spremljali 3 parametre. Največjo tvorbo strokov smo izmerili pri sevu HGR-6 in rasti pri 400 µg g-1 Al. Največ nodulov je bilo pri inokulaciji s HGR-6 in HGR-13 pri 200 µg g-1 Al. Vsebnost leghemoglobina je bila najvišja pri inokulaciji s HGR-13 pri 400 µg g-1 Al. Sev HGR-13 je imel biosorpcijski potencial tako v tleh kot v koreninskih nodulih celo pri 300 µg g-1 Al, največji pa je bil pri 100 µg g-1 Al. Raziskava kaže, da imajo rastline vrste Macrotyloma uniflorum , ki so inokulirane s sevi Rhizobium HGR - 4, 6, 13 in 25 poleg sposobnosti vezave dušika tudi sposobnost rasti v tleh, onesnaženih z Al. Zato so lahko take rastline primerne za fitoremediacijske postopke s kovinami (Al) onesnaženih tal.