RESULTS 



Various trees, both S^'s and outcrossed half-sibs, many represented by only a few 

 trees per line, could be crossed only to the extent of their variable and often limited 

 female or male fruiting. An extremely uneven mating pattern resulted, rendering many 

 statistical analyses impractical. The only analyses attempted are estimations of the 

 significance of the mean differences between Sj's and their related but outcrossed half- 

 sib lines as to mortality, timing and extent of strobilus production, success of cross- 

 ing, female strobilus loss, numbers of filled and hollow seeds, and seed weight 

 (table 3). The body of data is large enough, however, to allow conclusions on the 

 limitations and practicality of continued inbreeding in western white pine to be drawn 

 with some confidence. 



Survival of Si Trees 



In 22 Sj lines, a total of 109 trees survived exposure to the blister rust fungus 

 in the nursery and were transplanted into the arboretum. Of these, 72, or 66 percent, 

 survived in 1972, or at least had fruited prior to death (table 3) . In comparison, 

 92 percent of the 1,014 outcrossed trees, in 140 full-sib and 18 wind-pollinated lines, 

 all half-sib to one or the other of the Sj lines, survived or had fruited. More than 

 25 percent lower survival in S^'s was significant. Nevertheless, survival was adequate 

 for proceeding with second- generation inbreeding. Survival seems to be somewhat higher 

 in lines from self-fertile parents like 25 and 58. 



Comparative Delay and Extent of Fruiting of S, Trees 



Onset of fruiting, and its extent in seasons fruited, proportion of trees fruiting, 

 and total number of strobili borne are also shown in table 3, for 18 surviving lines 

 and their corresponding outcrossed half-sib lines. It is remarkable that bearing of 

 female strobili by S^'s as compared with outcrosses is delayed only about 3 years, and 

 that a higher proportion (more than 20 percent) of the trees bore female strobili. 

 Perhaps female fruiting is under control of one or a few recessive genes, and thus is 

 enhanced by selfing. Otherwise, all features of timing and extent of female fruiting 

 are in favor of the outcrossed half-sibs. In the Sj trees, male fruiting is delayed 

 more than two, probably several, years. Female strobili are borne only two-thirds as 

 frequently, male strobili one-fifth as frequently; over 20 percent fewer trees produce 

 male strobili; and total strobilus counts are only one-fourth (female) to one-sixth 

 (male) as great as in the related half-sibs. 



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