THE PERSIAN WALNUT 
A Typical Problem in Tree Breeding—Great Improvement in the Past Due to 
Unconscious Selection and Chance Hybridization—Much 
Greater Progress Possible in Future, Through 
Intelligent Methods. 
J: RussELL SmitTH 
Professor of Industry, University of Pennsylvania, Philadelphia, Pa. 
NE of the most significant state- 
ments I know in connection 
with the whole matter of 
agricultural extension on the pro- 
duction side is the following from C. S. 
Sargent, in connection with the Persian! 
walnut (Jwglans regia). 
“The nut of the wild tree is small, with 
a thick hard shell, and small kernel, and is 
scarcely edible, but centuries of cultivation 
and careful selection have produced a 
number of forms with variously shaped 
thin shells, which are propagated by 
grafting and budding.”’ (Silva, Vol. VII, 
pelLs:) 
To persons familiar with the big, 
sweet, nutritious nuts now so common 
in the world’s market, it is indeed 
difficult to believe this statement as to 
their original unpromising condition. 
This improvement appears to have come 
by chance breeding which has given a 
splendid tree crop for the Mediterranean 
climate where it seems to have originated, 
and it has also given a most stimulating 
object lesson of the means by which 
we may duplicate the process in 
walnuts of several species and for scores 
of other trees that are not now crops at 
all. The method by which the mag- 
nificent Franquette or Mayette walnuts 
have come out of the mean parentage 
described by Sargent is probably as 
follows : 
Centuries ago, perhaps dozens of cen- 
turies ago, people in southern Europe 
and western Asia carried home the 
seed of wild walnut trees from the woods 
as we do now with black walnuts, 
chestnuts, hickories, hazels and other 
wild nuts. They planted of the best in 
their gardens. This may properly be 
called a selection of one in hundreds. 
Of the resulting seedling most were 
certainly poor trees from the horti- 
cultural standpoint, but one out of a 
hundred was likely to be good, perhaps 
better than the parent. From what we 
know of human nature wrestling with 
the problem of stomach-filling, this best 
tree became the parent of the next 
generation of seedling walnuts in that 
valley or the next valley—again a 
selection of one in a hundred. We now 
have the hundredth tree from the 
hundredth tree. This may easily have 
been repeated ten, twenty, or even fifty 
Or. gore, - timiesim. Phe” “best aseedlin® 
walnuts of today thus represent the 
selection from among a vast number 
of seedlings. 
SELECTION IN BOTH SEXES 
But hold—this is not all. These 
seedlings have not been yielded by extra 
good females fertilized by average males. 
The collections of seedlings from selected 
seed have often given chances for the 
crossing of two selected strains. To all 
intents and purposes we have had 
practical walnut breeding going on—but. 
1 The name ‘‘walnut’’ means merely ‘‘the foreign nut,’’ and was given by the early English 
because the nut came from abroad. The name “English walnut,’’ under which the Persian 
walnut passes commercially in America, is due to the fac tthat many of the nuts were transshipped. 
to this country in England; but as it is an absolute misnomer, the name “Persian walnut’’ is 
now generally used among growers. 
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