Casuarina equisetifolia, (Chavukku in Tamil) have been planted worldwide for serving fuel wood, land reclamation, dune stabilization and as shelter belts.
This tree is planted in about 0.5 million hectares in the states of Andhra Pradesh, Tamil Nadu, Puducherry and Orissa.
Economic value
Due to its high economic value farmers are interested in planting this tree as an agro forestry crop in Tamil Nadu and Pondicehrry. C. equisetifolia fixes atmospheric nitrogen through bacteria called Frankia in root nodules.
This bacteria fixes atmospheric nitrogen up to 362 kg/ha/year which is an essential nutrient for plant growth. Generally farmers used to collect the root nodules from mature trees of C. equisetifolia and then crush and add at the time of planting in new sites.
Often unsuccessful
This practice is often unsuccessful if the crushed root nodule contains dead or inactive Frankia. Further, for pulp and paper production high yielding genetically superior trees of C. equisetifolia are selected and multiplied by rooted stem cuttings.
But the rooted stem cuttings are being propagated in an inert material (vermiculite) so that there is no chance for Frankia association.
Therefore after planting of these stocks 150 Kg of Di Ammonium Phosphate (DAP) per acre at the age of 6-12 and 18-24 months is required.
Instead of using crushed root nodules for nitrogen fixation in seedlings and rooted stem cuttings of C. equisetifolia an alternate method was developed with funding support of Department of Bio Technology, New Delhi as follows.
The bacteria Frankia was isolated and cultured in an artificial media 5 ml of culture in liquid form was applied in the rooted stem cuttings of C. equisetifolia under nursery conditions.
Lower fertilizer need
After 30 days of application the root nodules (nitrogen fixing sites) were observed in the stem cuttings.
This technique fixes the Nitrogen in C. equisetifolia at very low cost level which also reduces the use of chemical fertilizer.
The farmers may approach Institute of Forest Genetics and Tree Breeding, Coimbatore ? 641002 to obtain this Frankia culture for application in seedlings and rooted stem cuttings of C. equisetifolia.
