Bio-hardening of in-vitro raised plants of Bhagwa pomegranate (Punica granatum)

A pot culture experiment on bio-hardening of the in-vitro raised plants of Bhagwa pomegranate (Punica granatum L.) was conducted to find out the effect of two commercially available bio-formulations containing Arbuscular Mycorrhizal Fungi (AMF) and Aspergillus niger strain AN-27. Observations on root colonization, population dynamics of microbes in rhizospheric soil, growth, physiological and biochemical parameters of biohardened plants were recorded at 180 days after inoculation. Results revealed that AMF colonization in roots of in-vitro raised pomegranate plants was found at par in plants inoculated with AMF (71.12%) and AMF + Asp (65.00%) the root colonization in these two treatments was significantly higher than Contral (10.00%). Population of Aspergillus niger in the rhizospheric soil was found significantly higher in soil inoculated with Aspergillus niger strain AN-27 (6 × 104 cfu/g of soil) as compared to non-inoculated control (2 × 104 cfu/g of soil). Significant improvement in plant height (27.0% increase), shoot fresh weight (24.8% increase), root fresh (23.3% increase) and dry weight (15.7% increase) was observed in bio-hardened plants than untreated ones. Physiological processes were also significantly improved by bio-hardening as AMF and AMF + Asp treated plants registered significantly better RWC (92.34 and 91.74 %, respectively) and photosynthesis (12.69 and 12.78 µmol CO2m-2s-1, respectively) as compared to control (87.76 % and 9.07 µmol CO2m-2s-1, respectively) and only Asp treated plants (89.99% and 9.70 µmol CO2m-2s-1, respectively). AMF inoculated and AMF + Asp treated plants registered significantly higher total leaf chlorophyll (2.97 and 3.14 mg/g fresh weight, respectively) and total phenolic content (53.00 and 52.50 mg catechol equivalent/ 100 g fresh wt., respectively) than the control and only Asp treated plants