CONE ATTRIBUTES AS INDEXES OF SEED MATURITY AND EFFECT OF CONE AND SEED GRADES ON SEED-GERMINATION AND VIGOR IN CASUARINA-EQUISETIFOLIA JR AND FROST,G.

Physiological maturity of seeds as measured by maximum seed dry weight and peak germinability was attained only 18 weeks after anthesis in Casuarina equisetifolia. This coincided with a colour change of cone from green to brown and a fall in cone moisture content below 50%. However dimensional attributes of cone were not associated with seed maturity. Estimation of three weight grades of cones viz., light ( < 4.0 g), medium (4.1 to 6.0 g) and heavy ( > 6.1 g) revealed seed from heavy cones to have high germinability, vigour index and maximum weight. A comparison of four density grades of seeds graded in a South Dakota seed blower with ungraded seeds indicated only those retained at the highest air-speed setting had higher germination and vigour. Collecting seed when the cones turn brown, and using dense seeds from large cones is recommended.