FOREST GENETICS — AUSTIN 437 



Although these and other findings here reported will, obviously, 

 need checking by further experimentation, enough has been learned 

 to demonstrate the tremendous practical possibilities that these 

 methods offer to whomsoever will put them into use. 



There probably will be no one best strain of any one species of pine 

 for all timber-growing climates and soils where the species is to be used. 

 Various superior strains will be needed, and as these are gradually 

 developed and widely tested, they can be expected to exhibit some 

 variation in the expression of their hereditary characters in different 

 localities, depending on the local environmental conditions. Con- 

 sequently, various field trials will be required to determine just which 

 of the better strains are best adapted to each locality. In this way 

 we will insure the maximum growth and highest quality of lumber 

 possible under each set of conditions. 



From still another line of experimentation has come valuable new 

 information that demonstrates the practicability of improving the 

 strains of forest trees within a reasonable length of time. Many had 

 thought that it would usually be necessary to wait until seedlings 

 were 15 to 20 years old or more before they would flower so that 

 hybridization experiments could be conducted with artificially grown 

 trees. But tests in the Institute's nursery and arboretum have shown 

 that many different species of conifers, particularly pines, flower at 

 the early ages of 2 to 5 years. 



Astonishing as it may seem, one Chinese species of pine, Pinus 

 sinensis, actually blossomed profusely in the nursery at the age of 

 1 year from seed, thus causing pine breeding to approach, in some 

 respects, the facility with which annual crops, such as wheat and corn, 

 can be hybridized. As early as 1932 no less than 44 species of forest 

 trees were flowering in the Institute's arboretum, although the first 

 plantings were made only 6 years before, and many of the trees were 

 considerably younger than this. Among those that flowered at this 

 early date were several 2-year-old seedlings of the Japanese red pine, 

 Pinus densiflora, grown from seed collected in the arboretum. Not 

 many species are quite as precocious as this, but the average age of 

 initial flowering for pines has been found to be so low that cross polli- 

 nation experiments can be conducted with them and tree generations 

 can be secured much more rapidly than had been anticipated. 



Another discovery offering much encouragement to the pine breeder 

 is the great longevity of pine pollen. Simple and inexpensive methods 

 have been found that will often keep this pollen viable for a year or 

 more. This is in sharp contrast to the condition that exists in some 

 other plants, such as corn, in which the pollen lives only about 24 

 hours, and if not used within that time is of no avail. The long life 

 of pine pollen makes possible its shipment from the forests of distant 



