4 Plant Physiology 



Through physiological study it is possible to understand 

 better that which pertains to production, since increased 

 knowledge of plant response makes it more nearly possible 

 to modify opportunely and to improve upon current prac- 

 tices of production, and to develop progressive varieties 

 and strains. Obviously, production involves a variety of 

 nonphysiological conditions, but it also involves physio- 

 logical conditions, and little progress may be anticipated 

 without an intimate knowledge of the relation of the 

 growth of the plant or crop to the conditions under which 

 it is grown. 



3. Physiology and ecology. - - At the outset, moreover, 

 it is necessary to recognize two possible lines of study and 

 observation. The one is primarily concerned with the 

 isolated and controlled plant and the functions or responses 

 of its diverse organs and structures. This is generally 

 considered pure physiology. The other line of study deals 

 with plants or the crop in the field, or stated technically, in 

 a natural or seminatural habitat. This is field physiology 

 or ecology. There is, of course, no sharp line between 

 the two subdivisions indicated, and both are important in 

 production. It is necessary to know the plant, and it is 

 equally essential to know the environment, for that is the 

 sum of the conditions to which the plant responds. 



4. Physiological processes. - The engineer who does 

 not understand his machine cannot expect to get effective 

 work out of it. He should know its intimate structure, 

 what work it can perform under all conditions, and how it 

 may be controlled. In the same way the plant producer 

 who knows the structure of the plant and its behavior is 

 provided with the means of interpreting the effects of con- 



