PHYSIOLOGICAL BASES OF CROP 

 PRODUCTION 



W. L. BURLISON, Professor of Crop Production 



HROUGHOUT all ages the growth of plants has inter- 

 ested thoughtful men." "The beginning of plant culture 

 goes far back into history." "The mystery of the change 

 of an apparently lifeless seed to a vigorous growing plant 

 never loses its freshness." And it is evident, too, that as 

 time goes on and the world's food problem becomes more 

 complex, this interest will steadily develop. 



A review of some of the world's literature relating to agriculture 

 reveals many interesting statements. It was thought by some gar- 

 deners that the moon exercised a controlling influence on the growth 

 of plants. Others thought that the ruling force was an unknown 

 God whose power never could be known. Before the advent of the 

 fifteenth century, speculation and superstition ruled supreme. Since 

 about the middle of the fifteenth century, plant culture studies have 

 passed through certain rather well defined epochs, each in turn con- 

 tributing valuable information and thus enlarging and enriching our 

 knowledge of how plants grow. 



THE SEARCH FOR THE "PRINCIPLE OF VEGETATION"* 



Almost five centuries ago, Palissy said : "You will admit that 

 when you bring dung into the field it is to return to the soil some- 

 thing that has been taken away. When a plant is burned it is reduced 

 to a salty ash called Alcaly, by apothecaries and philosophers every 

 sort of plant, without exception, contains some kind of salt. Have 

 you not seen certain labourers when sowing a field with wheat for the 

 second year in succession, burn the unused wheat straw which had 

 been taken from the field. In the ashes will be found the salt that 

 the straw took out of the soil ; if this is put back, the soil is improved. 

 Being burned on the ground it serves as manure because it returns 

 to the soil those substances which had been taken away." These 

 facts have been confirmed in part from the study of chemistry. 



Early in the sixteenth century, a search for the "principle of veg- 

 etation" was begun by Von Helmont. His work is regarded as the 

 classic of its time. In speaking of his experiment, Von Helmont says: 

 "I took an earthen vessel in which I put two hundred pounds of soil, 



*RusselPs Soil Conditions and Plant Growth. 



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