1919] Coit-Hodgson: Abnormal Shedding of Washington Navel Orange 319 



average humidity as it is the greater freedom from extreme variation 

 in climatic conditions which serves to enable the young fruits to 

 survive. 



As referred to above, the junior author 49 has shown in another place 

 that a marked water deficit occurs both in the young fruits and the 

 leaves under the climatic conditions obtaining at Edison and has sug- 

 gested that these abnormal water relations furnish the stimulus to 

 abscission. If this be so, then when there is little or no dropping of 

 the fruits and consequently a good crop, such abnormal water relations 

 should not be found. An effort was made at the East Bakersfield 

 station in 1917 to establish such abnormal water relations, but it was 

 found impossible to do so (table 8). Instead of there being a regular 



TABLE 8 

 Average Moisture Content at Different Times of Day 



Average water content in 

 per cent, calculated on 

 basis of dry weight 

 Kind of material 1916 1917 



Normal fruits one-third to three-fourths inch in diameter 



gathered before noon 260.2 285.3 



Same, but gathered after noon 247.0 283.9 



Leaves of current season's growth, gathered before noon 164.9 174.9 



Same, but gathered after noon 157.2 182.6 



decrease in water content of similar leaves and fruits during the day, 

 which is made up during the night, no such relation was found. At 

 East Bakersfield the leaves and fruits, in the first place, averaged 

 somewhat higher in moisture content than those taken at Edison. 

 Secondly, although as nearly similar in every respect as possible, 

 duplicate series showed an absolute lack of uniformity, the variation 

 sometimes being as much as 30 to 40 per cent. Finally, no average 

 decrease in water content either of the fruits or leaves was found 

 to occur during the day. It should be mentioned that irrigation at 

 the Kellogg place is not uniform, relatively small tracts being irri- 

 gated at one time and these thoroughly soaked. As it was found in- 

 convenient to take all the leaves and fruits from the same trees it is 

 possible that some of the variation in moisture content noted may be 

 attributed to variations in soil moisture. However, under the marked 

 modification of climatic conditions which has been shown to occur as 

 a result of the management of the orchard, it is believed that such 

 abnormal water relations do not occur, at least to anything like the 

 extent to which they do under the unmodified climatic conditions. 



49 Loc. cit. 



