19161 FIELD CROPS. 531 



Correlated characters in maize breeding, G. N. Collins (U. S. Dept. Ayr., 

 Jour. Agr. Research, 6 (1916), No. 12, pp. 435-454, pls. 9).— This article reports 

 the results of a study undertaken " to determine whether the difficulty in 

 recognizing types of maize is duo to a lack of familiarity with the plants or 

 whether there is a fundamental difference between the heredity of maize and 

 that, for example, of cotton." It was thought that the difficulty of recognizing 

 types among maize plants might be due to a lack of sufficient discrimination 

 and that correlations were the rule rather than the exception. The data ob- 

 tained were afforded by a cross between Waxy Chinese and Esperanza, Chinese 

 and Mexican varieties respectively, with a number of definitely contrasted char- 

 acters and considered completely isolated from very remote times. Tables are 

 given showing the mean of different characters and the coefficient of variation 

 of characters in first and second generation plants, correlation coefficients, 

 and character pairs exhibiting genetic correlations. The following characters 

 are discussed : Hairs on the leaf sheath, tassel characters, tassel exsert, num- 

 ber of erect leaf blades, angle of tassel axis, and one-sidedness or the peculiarity 

 that a number of the upper leaf blades are borne on one side of the plant. 



The results are reported as showing that the characters studied, instead of 

 forming coherent groups, are almost completely independent in inheritance. For 

 the purpose of distinguishing different kinds of correlations they are classified 

 as physical, physiological, and genetic, and a method is proposed by which 

 physiological and genetic correlations may be distinguished. 



For the study of correlations 11 of the characters most definitely contrasted 

 in the parents were selected and the correlation coefficients of all the combina- 

 tions were calculated. Of the 55 possible combinations, 20 were found to ex- 

 hibit significant correlations, but in all but 5 of these correlations are believed 

 to be physiological rather than genetic. No correlation was found between 

 any two characters closer than 0.5, which fact is regarded as offering an ex- 

 planation of the difficulty of recognizing types in inaize. 



" This lack of coherence of characters in maize, taken with the fact that 

 to maintain a satisfactory degree of vigor a diversified ancestry must be main- 

 tained, would appear to make the method of isolating types inapplicable to this 

 plant. As an offset to the limitation thus imposed, advantage may be taken 

 of the facility with which desirable characters derived from different parents 

 can be combined." 



Cooperative fertilizer experiments with corn, 1908—1914, G. S. Fbaps 

 (Texas Sta. Bui. 184 (1916), pp. 3-64).— The results secureil during the first 

 three years have been previously reported (E. S. R., 25, p. 627). This bulletin 

 deals mainly with the experiments carried on from 1911 to 1914. Tables are 

 given showing the results secured by the different cooper ators and the com- 

 position of the soils on which the tests were made. The details of each test are 

 briefly noted and the effect of the different fertilizers or fertilizer ingredients 

 is discussed. 



During the seven years, 114 experiments were made and in 87 of this number 

 a gain was secured from acid phosphate, in 76 from cotton-seed meal, and in 

 46 from potash. It is concluded from the data that the soils concerned need 

 phosphoric acid first, nitrogen next, and potash least. Using from 150 to 200 

 lbs. of acid phosphate the average gain produced was from 5 to 7 bu. of corn per 

 acre. From ."^O to 100 lbs of cotton-seed meal, there was an average gain 

 of 0.4 to 3.8 bu., when used in combination with acid phosphate, while with 200 

 lbs. of cotton-seed meal, alone or with acid phosphate, there was from 5.5 to 7.1 bu. 

 increase, the results being based on only those experiments in which a gain 

 occurred. From 5 to 25 lbs. of muriate of potash per acre, there were produced 



