170 IRRIGATION PRACTICE 



well established and may be safely accepted, yet it is 

 not to be forgotten that much work must yet be done 

 with the various crops before a full knowledge of the 

 subject is in our possession. We may say with a certainty 

 that the leaves, stems, seeds and roots of crops are influ- 

 enced definitely by varying the quantity of irrigation 

 water. We do not know definitely, however, how the 

 yield of fruit is affected by varying quantities of water, 

 although in view of the high value of the fruit crop, this 

 is a particularly important need. It is probably true that 

 the production of fruit depends upon the time at which 

 water is applied rather than upon the total quantity of 

 water. However, from early springtime each tree sends 

 forth its leaves, and the materials elaborated by the 

 leaves are distributed throughout the whole tree to 

 develop roots, trunk and branches, and to produce fruit. 

 Undoubtedly, the quantity of water applied plays an 

 important part in determining how these elaborated 

 materials shall be used in the tree. In so large a struc- 

 ture as a well-matured fruit tree it must be of great impor- 

 tance to know how the materials gathered from the soil 

 and air may be driven into the fruit, without injuring the 

 well-being of trunk, branches and roots of the tree. That 

 the fruit crop is as sensitive as other crops to the effects 

 of varying quantities of water is well shown in several 

 experiments. For instance, Jones and Colver, in a study of 

 the composition of irrigated and non-irrigated fruits, 

 conducted under the auspices of the Idaho Experiment 

 Station, and using fruit grown under the somewhat 

 humid conditions of northern Idaho, found that the pro- 

 portion of seeds, skins and other wastes of fruits was 

 high or low as the fruit was or was not irrigated. The 

 following table gives some of the results: 



