Two young Douglas fir were self-pollinated in 1952 and results showed a wide variation in self-incompatibility, one tree producing a fair number of viable seed. It is suggested, that a considerable range of incompatibility following selfing exists within the species and that this is due to some factor that inhibits normal seed development in varying degrees. Cytological examination of material from the highly self-incompatible trees showed that the embryo aborted at an early stage following self-pollination. The harmful effects of inbreeding were clearly seen in the progeny of the one tree, there being highly significant differences in height growth when compared with seedlings resulting from controlled cross- and wind-pollination of the same tree. The importance of the selfing technique and the practical implications of inbreeding are emphasized. A few viable seeds were obtained from unpollinated cones, the resulting seedlings are very uniform, and cytological examination has shown that they are diploid. Further investigations on self-incompatibility and agamospermy in the Douglas fir are being pursued.
The results from inbreeding studies with the Douglas fir have conclusively shown that the effects of self-pollination vary widely in different trees as the yield of viable seed was sharply reduced in some trees and not in others. The inbred progeny was usually weaker and less vigorous than that resulting from the controlled cross-pollination of the same parent tree. The progeny from wind-pollination, where the pollen parent was not known, varied greatly and some of the seedlings showed all the characteristics of inbreeding. The value of inbreeding to future tree improvement programs and the practical applications of self-pollination to current forestry practice are discussed.
T h e Do~eglus-fir, one o f t h e most i m p o~t a n t specics in z~e s t e r n N o r t h A n z e~~i c a , has b e e n zoiclel y plnntecl in coastal B r i t i s h Colzembia since 1930. T h e present measzires being t a k e n b y t h e B9,itish Col7cnzbiu Forest Service, I n d z~s t s y and t h e U n ivelssity o f B r i t i s h Colz~nzbia t o irnpl.ove t h e genetic qzculity o f t h e large antou)zts I t i s notecl t h a t a t t h e pq-esent t i m e m o r e t h n n 90 pet. cent o f t h e Douglas-fir seecl i s collected f 7 o m u n i r n p~o v e d stancls. I t i s consicle).ecl t h a t t h e cic?.eage o f t h e seecl prodziction areas and t h e plci~~necl enapaq~sion of seed o?*cha7.ds zoill n o t be sufficient t o enszo-e t h a t fzitzire collections zc;ill be f 7 . 0 7 )~ inzp?80vecl seecl sozcrces. An i m m e d i a t e els11ansi0)~ o f seed ~~~~o c l z i c t i o n a7.eas i s szcggestecl a s a n intelinz ?neaszo*e. I t i s consicleq.ec1 t h a t there i s c/?*eat potential fo?. t h e genetic imp?.oveme?zt o f ~o u g l a s -f i r as it has a l~e a d y been clemonstrated t h a t t h e species i s uclaptable t o radically diffe?.ent wethocls of b7,eeding.Resume Le developpement d'un programme pour I'amelioration genetique du sapin de Douglas en Colombie-Britannique. L e S a p i n cle
Grafting is a valuable technique for foresters interested in improving seed-quality as the inherent characteristics of selected trees can be preserved indefinitely for breeding and seed orchards. Dormant scions of the Douglas fir can be collected in the winter and early spring by either climbing or shooting off branches with a rifle. They are stored until the rootstock is in an actively growing condition and are then either grafted in a greenhouse or outside. The cleft and crown veneer graft methods have been found the most suitable for this species. The possibilities of early cone production after grafting appear promising.
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