POLLEN PRODUCTIVITY VARIATIONS IN <em>PINUS</em> <em>ROXBURGHII</em> AT THREE DIFFERENT ALTITUDES IN GARHWAL HIMALAYA

Abstract

In Pinus roxburghii the variations in the number of production units, namely, microsporophylls, strobili and strobili groups per tree at three different altitudes have shown variations in pollen production. The total pollen production per tree ranged from 1247.5 X 109 (at 1900 m asl) to 1888.5 X 109 (at 900 m asl). An exponential correlation was observed between the size of microsporophylls and the number of pollen grains they contain. The ratios between the number of pollen grains per microsporophyll and the number of microsporophylls per strobili group, the number of pollen grains per strobilus and the number of strobili per tree, as well as the number of pollen grains per strobili group
and the number of strobili groups per tree showed a hyperbolic function.