836 EXPERIMENT STATION RECORD. 



light, air niovemonts, aiul precipitation to the growth of the wheat plant, and the 

 possible share of each factor in the production of yellow berry, was found to be 

 extremely complex and intricate. 



Relative to the influences of the autumn vegetative conditions on the produc- 

 tion of yellow berry, the data for the 2 years show the same diminution in the 

 percentage of yellow berry with the shortening of the fall vegetative period and 

 a corresponding decline in the mean temperature for that period. The first year 

 the planting season lasted over 19 days (from September 28 to October 16), cor- 

 responding with which there was a decrease in the average amount of yellow 

 berry of from 53.80 per cent in the highest to 19.58 per cent in the lowest case. 

 The second year, when the planting season covered a period of but 4 days (Sep- 

 tember 20-29) , there was apparently a correspondingly lower range in the average 

 percentage of yellow berry from the different plantings of from 44.33 per cent 

 in the highest to 32.63 per cent in the lowest. Apparently the reduction in the 

 total length of the growing period with the later plantings, the consequent lower 

 mean temperature for the period of fall growth, and the necessarily retarded 

 and diminished development of the plants is in direct correspondence with the 

 subsequent development of yellow berry, in so far as the data here secured are 

 concerned. 



A^egetative spring conditions did not disclose any very definite relationships 

 to the percentage of yellow berry. As the results were sometimes contradictory, 

 and always complex and difficult of interpretation, it was concluded that 

 hereditary tendencies in the varieties themselves might obscure results, and 

 accordingly work was begun to demonstrate whether or not yellow berry is a 

 heritable product. 



Among the many cultures of wheats examined, which were planted side by 

 side at the same time and. which ripened on the same date, the percentages 

 of yellow berry were found to vary widely. So-called commercial varieties, 

 which were really mixtures of wheats, were grown under identically the same 

 conditions In connection W'ith this investigation. Among them strains of differ- 

 ent tyi^e w^ere found, w^hich showed distinct physiological differences so far as 

 the production of yellow berry was concerned. The varieties grown in 1906 were 

 grouped into those wheats producing from 1 to 25 per cent, from 26 to 50 per 

 cent, from 51 to 75 per cent, and from 76 to 100 per cent of yellow berry. The 

 crop of 1907 from these groups showed in general that the averages of the 

 amount of yellow berry for each had the same relative position that they 

 occupied in 1906. The minimum range of yellow berry in the varieties lay in 

 those groups of 1907 that came from the minimum groups of 1906. Although 

 the varieties low in yellow berry had progeny in 1907 which averaged 12.25 per 

 cent higher than the average of the corresponding parental groups for 1906, 

 on the other hand the varieties high in yellow berry had progeny which 

 averaged 27.41 per cent low^er than the average of the corresponding parental 

 groups for 1906. It was further found that the progeny from selected hard 

 kernels from 8 apparently pure varieties planted in 1906 were much heavier 

 than those from soft grains, and that as a rule the yields from the heavy hard 

 grains were greater than those fi-om the softer kernels. 



The degree of inheritance of yellow berry in pure bred or pedigree wheats is 

 discussed, and the results secured in work along that line are reported. In the 

 first progeny group of the pedigree w^heats in 1907 a little over one-third pro- 

 duced no yellow berry at all, and the average of all was but 3.9 per cent, 

 whereas in the selections of spikes from the common commercial varieties, as 

 well as in the selections of hard and soft grains from these varieties, there 

 were no cases whatever where the offspring were free from yellow berry. The 

 averages for the lowest groups in the case of the common commercial varieties 



