TREE GROWTH AND SEED 



Swiss Experiments Show How Main Characteristics of Parent's Growth are 



Inherited by Seedlings — Seed Must be Selected with as Much Care in 



Forestry as in Horticulture — Limited Effects of Environment 



in Overcoming Bad Heredity. 



James B. Berry 

 Department of Forestry, Pennsylvania School of Agriculture, State College, Pa. 



At the Forest Experiment Station 

 / \ near Zurich, of which Dr. Arnold 

 / V Engler is Director, are a number 

 of intt resting investigations under way^ 

 which illustrate the inheritance by seed- 

 lings of the main characteristics of the 

 parent tree. No plant breeder doubts 

 this in the least, yet the fact remains 

 that the purchaser of tree seed seldom 

 questions its source, and then as to 

 region only. For instance, two plots 

 are covered with a good growth of 

 spruce seedlings varying in height 

 from three to 10 feet. The seedlings 

 on Plot I show more than 50% crooked 

 and twisted, unfit for the production 

 of high class material, while Plot II 

 contains less than 5% of material of this 

 character — a variance at once noticeable. 

 Inquiry as to the history of the two 

 plots brings out these facts : 



1 — that the seedlings on Plot I 

 originated from seed collected from a 

 mother tree of gnarled and twisted 

 form — yet not an extreme form. 



2 — that the seedlings on Plot II 

 originated from seed collected from a 

 mother tree of normal form. 



3 — that the two mother trees — the 

 deformed and the normal — occur in the 

 same quality site under similar condi- 

 tions of light, heat and moisture. 



A second experiment occupies two 

 adjacent plots, both supporting a 

 growth of spruce seedlings about fifteen 

 years of age, the planting distance being 

 the same in the two cases. The seed- 

 lings on Plot I, while entirely healthy 

 and vigorous, are rounding in form, 

 very dense in character and the branches 



are uniformly small. Plot II supports 

 a growth of seedlings entirely normal in 

 form and rate of growth. The seedlings 

 on Plot I ranged between 12 inches and 

 30 inches in height, and were as broad 

 as high; the seedlings on Plot II ranged 

 between three and six feet in height. 

 The history of the plots brings out these 

 facts : 



1 — that the seedlings on Plot I 

 originated from seed from a mother 

 tree which was characterized by density 

 of branching and slow growth, but of 

 normal form. 



2 — that the seedlings on Plot II are 

 the product of seed collected from a 

 mother tree of normal form and growth. 



3 — that the two mother trees — the 

 dense and the open, the slow gro\vth 

 and the normal — occur on the same 

 quality site under similar conditions. 



Spruce forms the basis, also, for a 

 third investigation; namely, the effect 

 of temperature in its relation to trans- 

 mitted characteristics. Seed was col- 

 lected from regions of mean temperature 

 varying by 10 - F, from that of Zurich to 

 northern Sweden, altitude and latitude 

 both forming a basis for computation. 

 Two or three rows were planted from 

 each lot of seed, the arrangement being 

 in regular order from the lowest to the 

 highest mean temperature. Today, 

 eight years after the inauguration of the 

 experiment, there results a " terrace "- 

 like formation, the relative height 

 growth varying directly with the mean 

 temperature. Another interesting fea- 

 ture of the same experiment is that it 

 brings out the fact that the length of 



^ See also Engler, Arnold. Influence of Source of Seed. Journal of Heredity, V, 4, 185, April, 

 1914. 



431 



