Report on Poplar Hybridization 1936

Abstract

Forest Seruicr, D r p n r t l n~n t of the Interior While there is plenty of poplar in the forests of .Eastern Canada and elsewhere, there is a el-owing scarcity of sound poplar wood of good quality.I n spite of the rapitllj~ increasing areas stocked with aspen poplar as a result of recent fires, such wood is very scarce, ant1 is finding many uses for match stock and for veneer. T h e Swedish match factories have for a long time relied on Russian wood, but it is now 'becoming very scarce, and Canadian match stock is rapidly entering the world market. Recently it has been found economical in Get-many (LVettstein, 1935 ) ant1 in Englantl (Lotbiniet-e, 1935) to raise aspen poplar untler forest Inanaeenient in order to obtain aspcn wootl of gootl (111~.lity in sufficient iunounts to satisfy the growing demands for it. Under natural conditions, gootl aspen wood is found growing only on the very best soils, and only a very small proportion of the immense areas at the present time stocked wit11 asp:-n in America and in Europe will ever yield good, sol~nd wood. T h e reason for t!lis is the Freat su5ceptibility of aspen to heart-rot, Irhich attacks it at an early age, in most cases before it has reachcd merchantable size. Only a sm;lll proportion of the aspen stands of niel-chantable size yield sound wood. I t is tllel-efore consitlered good fol-estl-y PI-;~ctice to find such methods of managing aspen stands as will retard the tlevelopm~nt of heartrot and will yield an increasing pl-oportion of sound wood of the size suitable for match stock and for vencer. T h i s can he accomplishetl through methods of si1vicultu1-a1 treatment of existing aspen stands and by the use of suitable varieties or strains of aspen that are more resistant to heart-rot :ind reach larger sizes tht-o~1g11 being longer-lived ant1 more vigorous than the existing 'aspen specles. T h i s report deals with this second phase of the problem, namely, the efforts leading towards the development of strains and of varieties yielding good, sound wood ~~n d e lforest management. I t has been found that a natural cross between the European silver poplar (Popult~s nlbn L.) and the European aspcn (Popult~s tremr~ln L . ) combines some of the good qualities of its parents. Silver poplar is a healthy vigorous tree, I-eaching larger sizes than the aspen. I t IS l e s~ subject to 1le;u-t-rot, and it grows faster than the aspen. I t has been found to yield wood of a q~~a l i t y suitable for match stock, although this wood is inferior to aqpcn wootl of the highest grade. T h e tree can easlljr be grown and pl.opaThe Forestry Chronicle Downloaded from pubs.cif-ifc.org by 52.183.12.225 on 06/07/19For personal use only.

Wood Quality and Growth Characterization across Intra- and Inter-Specific Hybrid Aspen Clones

“…Numerous studies have shown both significant and stable heterosis in F1 hybrids of Populus spp. However, the genetic cause is not yet fully understood [10,12,[20][21][22]. There are two main hypotheses commonly used to explain the genetic basis of heterosis: dominance and overdominance effects [23].…”

Report on Poplar Hybridization Ii 1937 and 1938

“…Most of this material can be easily propagated by means of root cuttings and shows great promise of yielding valuable varieties for direct use in forestry. The supposed natural hybrids of P. alba and P. grandidentata found in 1935 (Heimburger, 1936) and later (Peto, 1938) are in their juvenile shoots identi* cal with the artificially produced alba,grandidentata clones and thus their parentage is now certain.…”

“…A s the cane. scens,grandidentata clones already have shown great variation in their morphological characters (Heimburger, 1936), probably because one of their parents is a hybrid, a variation in physiological characters influencing propagability was expected. During 1938 and 1939 all the hybrids were propagated by means of root cuttines and grown in the nurserv.…”

“…Hardiness. disease resistance, and good propagability from stem: or root cuttings are a t present the most importa n t characters used in evaluating the young hybrids.T H E OBJECT of this report is to outline the further development of the poplar hybridization project initiated in 193 5 and described previously (Heimburger, 1936). I t is an attempt to produce new varieties of aspen poplars, suitable for reforestation on upland soils and yielding good, sound wood for the manufacture of match stock, veneer, and pulp.…”

Some Historical Notes on Forest Tree Breeding in Canada

“…The National Research Council provided facilities for laboratory work, and hired a geneticist, Dr. L. P. V. Johnson, t o work on tree breeding. Dr. Heimburger worked on breeding and acquiring breeding materials (18,19,20). Dr. Grace and the writer worked on vegetative propagation and the use of hormones t o stimulate the rooting of stem cuttings (11)(12)(13)(14)(15).…”