Cross-inoculation experiments were conducted in the greenhouse to test the rhizobia isolated from nodules of seven tree legumes for their effectiveness in
Vigna mungo plants. The tree legumes included
Albizia lebbeck
,
Dalbergia sissoo
,
Leucaena leucocephala
,
Pithecellobium dulce
,
Prosopis cineraria
,
Prosopis glandulosa
and
Prosopis juliflora
, all growing under arid environment. Rhizobia from these legumes formed nodules on the roots of
Vigna mungo except isolates from
Albizia lebbeck. Dry weight and nitrogen contents of
Vigna mungo plants increased significantly (P<0.05) in response to cross inoculation as compared to uninoculated control. Rhizobia from
Leucaena leucocephala and
Prosopis glandulosa showed significant increase in dry weight (P<0.05) and nitrogen contents (P<0.05) than other inoculated treatments. The natural rhizobia of wild tree legumes growing under arid environment show higher tolerance to prevailing adverse conditions like salt stress, elevated temperatures and drought. These rhizobia may be used to inoculate wild as well as crop legumes cultivated in reclaimed desert lands. These rhizobia may have specific traits that can be transferred to other rhizobia through genetic engineering tools. The cross infection of agriculturally important legumes with isolates from wild legumes may prove a useful means of increasing nitrogen contents within these plants.
