MSc

Ashoka is an important medicinal tree gaining economic significance in recent years. As the domestic production of the officinal parts of ashoka is quite insufficient to meet the demand of ayurvedic medicine manufacturing units there is an urgent need for developing appropriate technologies for growth promotion and increasing bark yield in ashoka.
Three separate experiments were carried out at the Instructional Farm attached to the College of Agriculture, Vellayani to develop agro techniques for growth promotion and increasing bark yield in ashoka during 2009-10. The nursery trial on ‘Techniques for quality planting material production’ consisting of combinations of four root trainer techniques, viz, root trainer (individual tubes – R1), root trainer (blocks – R2), poly bags (R3) and mud pots (R4) and four rooting media, viz, potting mixture (M1), potting mixture +dual inoculation with Rhizobium and AMF (M2), potting mixture + dual inoculation with Rhizobium and AMF + Rock powder (M3) and potting mixture +dual inoculation with Rhizobium and AMF + Rock powder + mixture of vermicompost, FYM and composted coir pith (M4) was conducted in CRD with four replications. The field experiment on ‘Micro site enrichment techniques for growth promotion’ consisting of combinations of four in situ rain water harvests, viz, micro site enrichment, micro site enrichment + micro catchments, micro site enrichment + micro catchments + vertical mulching and POP recommendations and two levels of irrigation, viz, irrigation at 50 % depletion of moisture and life saving irrigation was carried out in FRBD with three replications. The third trial on ‘Techniques for increasing bark yield’ comprising four treatments, viz, NAA 50 mg l-1, Kinetin 50 mg l-1 , Combination of NAA 50 mg l-1 and Kinetin 50 mg l-1 and control was conducted in CRD with three replications.
In the nursery trial, dual inoculation of seeds with Rhizobium and AMF and sowing in mud pots containing enriched rooting media consisting of potting mixture, rock powder and mixture of vermicompost, FYM and composted coir pith was found beneficial for improving biomass accumulation in ashoka seedlings. The quality of the planting stock was evaluated based on three growth indices, viz, sturdiness quotient (SQ), root growth potential (RGP) and seedling growth potential (SGP). Among the different treatment combinations, higher values of SQ were shown by R2M3 followed by R1M4. Mud pots filled with rooting medium consisting of a consortium of bioinoculants and biomanures sprinkled with rock powder registered higher root growth and seedling growth potential. Besides, economic analysis of the system also proved its contribution in relation to gross income, net income and BCR.

The combined effect of micro site enrichment + micro catchment + vertical mulching and life saving irrigation was found favourable for enhancing total biomass production including stem bark, stem and leaf. The above treatment combination also proved its superiority in terms of accumulation of biochemical constituents in the officinal parts of ashoka, viz, total phenol and tannin in both stem bark and leaves.

Seasonal consumptive use, mean daily consumptive use and crop coefficient were maximum when POP recommendation was combined with irrigation scheduling at 50 % depletion of moisture. Significant variations on crop water use efficiency, field water use efficiency and water productivity were observed due to main effects of treatments. In all cases, the trend was exactly similar. Micro site enrichment + micro catchment + vertical mulching which was on par with micro site enrichment + micro catchment and micro site enrichment but significantly different from POP recommendations improved crop water use efficiency, field water use efficiency and water productivity. Similarly, the effect of life saving irrigation was conspicuous and it enhanced all the above three parameters considerably. Interaction effects indicated the significance of treatment combination, micro site enrichment + micro catchment + vertical mulching and life saving irrigation in enhancing crop water use efficiency, field water use efficiency and water productivity. However, the least efficiency and productivity values were registered by POP recommendation with life saving irrigation or 50 % depletion of moisture.

Investigations on bark regeneration indicated the importance of application of kinetin in increasing bark thickness and yield. However, quality constituents like, tannin and phenol content of bark increased with combined application of NAA + kinetin.