478 Journal of Agricultural Research voi. xix, no. lo 



action; and it is an interesting possibility that the temperatures which 

 retard ripening may be sufficient to inhibit enzyms. It is well known 

 that plant growth, in which many of the processes are similar to those in 

 the ripening fruit, is inhibited by high temperatures. 



From the foregoing summary of the work that has been done on pear 

 ripening and storage it is apparent that for the varieties tested there has 

 generally been found an increase in sugars as the season advanced. The 

 data regarding acid are rather more conflicting. The work on storage and 

 time of picking of Bartletts has shown that the later pickings have given 

 a longer low temperature storage season and a higher quality in the 

 ripened product. 



In this investigation it has been the purpose to make a careful study 

 of the changes that take place in Bartlett pears from the Pacific coast 

 regions during the time they are developing, including the commercial 

 picking season and extending somewhat beyond it. The effect of the 

 time of removing the fruit from the tree on its content of acid, sugar, 

 starch, and moisture has been studied. It has also been the purpose 

 to determine the changes that take place in the fruit between the time 

 of picking from the tree and the time the fruit is in prime eating con- 

 dition — that is, soft and full yellow ripe — and to see if the temperature 

 at which the fruit is held during ripening has any appreciable effect upon 

 its composition. 



The principal part of the work was carried on with fruit from two 

 important pear sections of California. One lot was secured from an 

 orchard at Sacramento. This orchard is typical of the large Sacramento 

 River pear district and is grown on reclaimed, irrigated soil adjacent to 

 the river. The summer here is warm and dry, but abundant water is 

 available for irrigation. 



Fruit from a ranch near Suisun, Calif., was also used. This sec- 

 tion is slightly higher and nearer the coast than the Sacramento 

 district. Fruit from this section is quite representative of much of 

 the central California pear region away from the Sacramento River. 

 Fruit from both of these orchards was picked at frequent intervals 

 from early June, almost a month before commercial picking started, 

 until after the close of the shipping season. 



For purposes of comparison, fruit was secured from Medford, Oreg. 

 This is representative of well-grown fruit on heavy soil in a typical 

 irrigated Rogue River Valley orchard. Three boxes were secured 

 from this orchard, one picked July 19, about 18 days before commercial 

 picking started, one August 8, representing the beginning of the ship- 

 ping season, and one August 28, at the end of the shipping season for 

 Bartletts. 



Fruit was also secured from the Selah section of the Yakima Valley, 

 Wash. The first fruit from this section was picked July 28, 1919, 

 followed by a shipment August 13, at the beginning of the shipping 



