Poplars Can Be Bred to Order 



step was to make hybrid seed available 

 to the farmers. When this was done, 

 the planting of new strains spread 

 amazingly ; during the next 6 years hy- 

 brid corn came to occupy more than 80 

 percent of the land planted to corn in 

 the Corn Belt, with an increased yield 

 averaging about 20 percent. Although 

 existing hybrid pines may be expected 

 to increase the yield on plantation sites 

 to which they are adapted, no seed of 

 these superior tree strains is now avail- 

 able for general distribution. Devising 

 means for production and distribution 

 of those hybrids that seem worthy of 

 trial in the various regions is the next 

 step needed to capitalize on the results 

 of pine-breeding research. 



J. W. DUFFIELD, a geneticist, joined 

 the staff of the Institute of Forest Ge- 



153 



netics in 1946. A graduate of Cornell 

 and Harvard Universities, he worked 

 as a forester for the Forest Service in 

 Michigan and as a tree breeder for the 

 Northeastern Forest Experiment Sta- 

 tion. 



PALMER STOGKWELL is geneticist in 

 charge, Institute of Forest Genetics, a 

 branch of the California Forest and 

 Range Experiment Station, main- 

 tained by the Forest Service in coop- 

 eration with the University of Califor- 

 nia, in Berkeley. He has served with 

 the Boyce Thompson Southwestern 

 Arboretum in Arizona, the Carnegie 

 Institution in California, the Soil Con- 

 servation Service in New Mexico, and, 

 since 1937, the Forest Service. He is 

 a graduate of the University of Ari- 

 zona and holds the doctor's degree 

 from the Stanford University. 



POPLARS CAN BE BRED TO ORDER 



ERNST J. SCHREINER 



Scientific breeding has given us the 

 hybrid poplars that grow faster than 

 our native species and resist better the 

 inroads of insects and disease. New 

 hybrids now can be practically bred to 

 order. 



Poplars offer outstanding possibil- 

 ities for rapid improvement through 

 scientific breeding for several reasons. 

 First of all, nature has provided a wide 

 diversity of germ plasm, the stuff that 

 controls inheritance; there are a large 

 number of relatively rapid-growing 

 species and varieties that extend over 

 a wide climatic range. Because poplar 

 species hybrids are reasonably fertile, 

 one can create new types that combine 

 the best characteristics of many species 

 and varieties. Breeding is simplified 

 because branches cut from mature 

 trees can be made to flower and fruit in 

 the greenhouse. Most poplars can be re- 

 produced easily from stem cuttings. 

 Thus inherently excellent trees can be 

 utilized almost at once without con- 

 tinued breeding for many generations 



to get the type true from seed; a new 

 and improved hybrid can be multiplied 

 by cuttings with the assurance that 

 every tree will be exactly like the 

 selected individual. 



The painstaking, patient work of 

 improving forest trees began in Ger- 

 many in 1845, when Johann Klotzsch 

 crossed two species each of pine, oak, 

 elm, and alder, and observed that af- 

 ter 8 years his hybrids averaged one- 

 third taller than the parent species. In 

 the following 60 years scientists accu- 

 mulated additional evidence on the 

 occurrence of hybrid vigor in crosses 

 between tree species and varieties, but 

 there was no effort to create better 

 forest trees by scientific breeding. 

 Augustine Henry, professor of forestry 

 in the Royal College of Science, Dub- 

 lin, was the first forester to do some- 

 thing about it and to urge strongly that 

 the artificial production of trees by 

 crossing was a new and important field 

 of forest research. 



"In countries like our own," he said 



