Healing of Boreholes in Pinus roxburghh Sargent (Chir Pine)

Healing of boreholes involved sequential production of callus tissue and formation of vascular cambium by dedifferentiation and conversion of callus cells into cambium cells. Healing of boreholes was initiated by callus formation from edges. The callus growth on lateral sides of the hole has been observed to be more than top and bottom of the borehole resulting into formation of narrow elliptical shaped hole after healing upto two years. The healing percentage showed decreasing trend with increase in the diameter of boreholes. The boreholes of 0.50" (1.25 cm) diameter showed maximum healing percentage of 28.46 per cent and minimum healing percentage of 2.86 per cent was obtained in 1.25" (3.125 cm) diameter boreholes after one year of tapping. Whereas, the healing percentage in 0.50", 0.75" and 1" diameter boreholes was observed to be 70.73, 59.42 and 53.56 per cent, respectively after two years of tapping.