946 Report oF THE HorTICULTURAL DEPARTMENT OF THE 
increased in the case of some varieties but decreased in others; 
but in no case was the increase in yield sufficient to offset the 
added cost of shading. With the thicker cover the yield was 
greatly reduced. Earliness was little affected by the cover. In 
the cases of some varieties under the thicker cover, ripening was 
retarded. In these tests the great increases, either in earliness or 
in yield, reported by some experimenters have not been obtained. 
It appears probable that a cover of thinner material, permitting 
the passage of more light, would give better results. The most 
serious objection to shading strawberries as was done in these ex- 
periments is the interference with the access of light to the plants. 
We have, however, found that shading with the thinner cover 
Improves the size of the fruit and sometimes its general appear- 
ance though at the expense of sweetness. In this respect our 
experience agrees with that of previous experimenters. The 
cover also proved a very excellent protection against frosts and 
light freezes, as was expected. Herein shading is a matter of 
insurance. But merely in so far as protection from frost is con- 
cerned, this can be obtained more cheaply in some other way. 
DISCUSSION ON THE EFFECT OF SHADING ON PLANTS 
IN GENERAL. 
Shading makes three general changes in the environment of the 
plant of importance to it: (1) It conserves soil moisture by 
lessening evaporation and transpiration; (2) it increases the 
temperature of air and of soil, stimulating the plant to more rapid 
growth; (3) it diminishes the intensity of the light, promoting 
the growth of aerial vegetative parts but interfering Mi the 
fruiting function. 
The element of the environment that may be most 
widely varied by shading and at the same time the one 
that produces the most profound changes in both strue- 
ture and functioning of the plant is light, interference with 
access of which is accompanied by decrease in _ its 
tonic effect in retarding growth. The consequence is an exag- 
gerated growth of leaves and stems. Interference with 
access of light also interferes with assimilation, with resulting 
lessened manufacture of non-nitrogenous matter, this resulting 
in turn in weak development of cell wall and fibrovascular 
