Cone size and seed yield in young Piceamariana trees

Black spruce (Piceamariana (Mill.) B.S.P.) cones were collected in 1980, l981, and 1982 from young trees in four plantations of different ages. Nine measures of cone size, seed yield per cone, and seed weight were determined by cone analysis, and the variation among plantations and years was assessed by analysis of variance. Relationships among the nine measures were assessed by correlation. Cone length, cone weight, total scales per cone, potential filled seeds per cone, total seeds per cone, total filled seeds per cone, and seed efficiency were all depressed in 1981, the year of poorest cone production. Potential filled-seed yield and actual filled-seed yield were highly correlated with most cone-size measures but poorly correlated with each other. Pollen availability in 1982 was assessed by trapping and by counting pollen cones. The catch of pollen grains was positively correlated with the numbers of pollen cones per tree. Total filled seeds per cone in 1982 was strongly related to pollen availability....