MARKET DISEASES OF VEGETABLES. 5 



becomes practically negligible. Proper aeration is essential 

 for the continued life and respiration of vegetables. The 

 carbon dioxide liberated must be removed, and the neces- 

 sary oxygen must be supplied. If respiring cells are not 

 properly aerated, they die, a'nd spoil. 



The fundamental reason for the refrigeration of fruits 

 and vegetables is based upon the fact that refrigeration 

 retards respiration and digestion ; retards not only the ripen- 

 ing processes of fruits and vegetables, but also their decay, 

 which is due to the activity of bacteria and fungi. 



Relation of the Plant to Its Environment. 



The continued existence of protoplasm and therefore of 

 plants themselves is dependent upon external factors which 

 constitute the environment of plants. Some of these are 

 non-living, such as moisture, heat, light, and the air ; others 

 are living, such as other plants, or animals. The environ- 

 ment of a plant may vary within certain limits without 

 injury to the plant. However, if these limits are exceeded 

 for a sufficient period of time the plant becomes abnormal 

 or diseased and eventually may die. 



When plants or plant parts are shipped and stored as 

 fresh food products, they are subjected to conditions very 

 unlike those prevailing in the field, and care must be exer- 

 cised to make these such that the life of the plant or plant 

 parts is still possible. This means that the external condi- 

 tions must be controlled and kept within the narrow range 

 tolerated by the plant in question. Each crop must be 

 handled in a manner suited to its peculiar requirements. 

 This will depend upon the climatic conditions prevailing 

 during the growing season and at harvest; upon the methods 

 employed for culture and harvesting; upon the presence of 

 climatic or mechanical injuries; upon the maturity at har- 

 vesting; upon the method of packing or loading; upon the 

 type of container ; upon the length of the transportation and 

 storage periods; upon the season, and upon the climatic 

 conditions to which the crop will be subjected in transit. 

 Failure to provide proper conditions for plants or plant 

 parts in transit or storage results in the loss, annually, of 

 thousands of cars of fruits and vegetables. It may result 

 merely in an inferior product so far as appearance and 

 taste are concerned, or in partial or complete decay. 



The Relation of Plant Functions to Keeping Quality. 



It is well known that vegetables and fruits shrink in 

 transit and storage. Some of the shrinkage is due to read- 

 justment in the pack or load. . There is in addition to this, 

 however, a real decrease in the weight and volume of the 

 crops as can be determined by weighing and measurement. 



Usually there is a very considerable shrinkage immedi- 

 ately following the harvesting of a crop, due mainly to the 



