STUDIES ON IMPROVEMENT OF SYMBIOTIC NITROGEN FIXATION IN Albizia procera (Roxb.) Benth. UNDER MID HIMALAYAN REGION
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Date
2019-11
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UHF,NAUNI
Abstract
ABSTRACT
The intensive harvesting of forest resources have led to decreased nitrogen and organic matter content
in the forest soils. Biological nitrogen fixation (BNF) is a cheap renewable nitrogen source, essential to the
sustainable productivity of afforested sites. Biological nitrogen fixation offers economically and ecologically
sound means for reducing the requirement of nitrogenous fertilizer, thereby restoring the degraded ecosystem.
The present investigation entitled “Studies on improvement of symbiotic nitrogen fixation in Albizia procera
(Roxb.) Benth. under mid Himalayan region” was carried out in the Microbiology Laboratory of Department of
Basic Sciences during the years 2016-2019. Results of the study revealed that among the 10 different seed
sources, Baddi seed source of Himachal Pradesh and FRI seed source from Uttrakhand were found best for pod,
seed germination and seedling growth parameters. It is evident from the studies that larger seeds have greater
per cent germination than smaller seeds. Non significant variation between pod and seed traits with geographical
factors were noticed which indicated non-clinal variation. In total of 66 isolates, 38 from Himachal Pradesh and
28 from Uttrakhand were isolated fromroot nodules of Albizia procera seedlings. On the basis of authentication
tests only 38 isolates were confirmed as rhizobia. Among these 38 rhizobial isolates, 29 isolates were Psolubilizers,
27 isolates were siderophore producers and 19 isolates were HCN producers. Among the 21
rhizobial isolates from Himachal Pradesh maximum P-solubilization (263.23µg/ml), siderophore production
(106.30%) and IAA (82.75µg/ml) was recorded with rhizobial isolate BA2. Whereas, maximum P-solubilization
(261.00µg/ml), siderophore production (108.12%) and IAA (85.52µg/ml) was recorded with rhizobial isolate
FA6 from Uttrakhand. Rhizobial isolates BA2 and FA6 also showed high per cent growth inhibition against 6
fungal pathogens. On the basis of plant growth promoting traits and antifungal activities, two isolates BA2 and
FA6 were selected and applied as biofertilizers. Both the biofertilizers with 20kg/ha nitrogen significantly
increased shoot biomass, root biomass, nodulation status and available N P K content of soil over uninoculated
control. These isolates were identified as Rhizobium leguminosarum (BA2) and Rhizobium alamii (FA6). The
application of charcoal based bio-inoculant of rhizobial strain FA6+20 kg/ha nitrogen has not only significantly
influenced growth characters and nitrogen fixation potential of Albizia procera seedlings but also improved the
available N P K content of the soil. Hence, application of charcoal based bioinoculant with rhizobial strain FA6
have enormous potential to be used as biofertilizer for enhanced growth, nodulation status and protection of
A.procera seedlings and to sustain soil health.
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