Micropropagation of Paulownia fortuneii through in vitro axillary shoot proliferation

This research article reported our successful establishment of primary cultures using nodal segments from juvenile shoots of two-year old Paulownia fortuneii trees from a clonal plantation in Andhra Pradesh. A medium containing half-strength MS salts + BAP ( I mg/L) + sucrose (2%) produced optimum bud break in nodal explants. The same basal medium with reduced hormone level (0.5 mg/L) supported maximum multiplication of secondary cultures of P.fortuneii ( I :6 in 6 weeks). Specific treatments were tested to enhance this rate of multiplication. In one approach, five to six week old in vitro grown shoots were ratooned (cutting the main shoot at the bottom leav ing one node). The stumps (ratooned basal node) produced 2 to 3 axillary shoots, which grew into 4 to 5 nodes by 3 weeks; thus, providing additional shoots from the same explant. This provided 30% additional shoots in 4 cycles.