BCOKS AND CURRENT LITERATURE 



Transpiration of Corn. — A recent comprehensive study by Kies- 

 selbach' is a very material contribution to our knowledge of the water 

 relations of plants as a factor in crop production. Laboratory methods 

 of study on transpiration were applied to corn plants grown in large 

 potometers in the field. The yield from these plants was entirely 

 normal when compared with plants grown under usual conditions, so 

 the results of this study are to be regarded as far reaching in giving 

 a correct understanding of the principles involved in the use of water 

 as influenced by cultural practices. 



In periods of drouth on days of extreme temperature, a single corn 

 plant may transpire as much as 10 pounds of water in twenty-four 

 hours. Transpiration may be 300 to 400 times greater one day than 

 the following day. Fulty one-half of the total water used by the plant 

 occurs in the four or five weeks' period following its maximum develop- 

 ment of leaf area. It was found from the results of three- years' tests, 

 that the lowering of the water content of the soil below the optimum 

 was accompanied by 37.3% decrease in stalk yield, 28.5% in year 

 yield and 30.7% in total dry matter. The increase in soil moisture 

 content above the optimmn was accompanied by a reduction in stalk 

 yield of 1L3%, in ear yield of 27.1% and in total dry matter of 16.7%.. 



Increase in fertility of the soil by the application of manure was 

 found to reduce the water requirement for grain production. A range 

 in variation of from 230 to 296 pounds of water per pound of dry matter 

 existed in the eleven varieties of corn tested. The so-called drouth- 

 resistant varieties of corn possessed practically the same water require- 

 ments per pound of dry matter as did the other varieties. 



Considerable variation existed in the different varieties of corn in 

 thickness of leaf and number of stomata per unit of leaf area with no 

 apparent correlation, however, between these anatomical differences 

 and the transpiiiation rate per unit of dry matter. The total area of 

 the stomatal apertures when open occupied 1.52% of the entire leaf 

 area. — F. A. Wolf. 



^Kiesselbach, T. A. Transpiration as a Factor in Crop Production. Neb. 

 Agr. Ex. Sta. Res. Bull. 6: 1-2U, 1916. 



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