444 ANNUAL REPORT OF THE Off. Doc. 



aji^eneies; and its intensity is dependent primarily upon the amount 

 of light received during the latter stages of maturity. In other 

 words, we get back to its de])endence upon maturity and sunlight. 

 Conditions increasing one or both of these factors, such as late pick- 

 ing, light soils, open pruning, and sod culture will increase color. 

 Opj>osite conditions decrease it. 



From (his viewpoint, the reduction in color caused by the nitrates 

 and the manure is easily explained. It is evidently due to delayed 

 maturit}'. That such is the case was shown the past season, es- 

 j)ecially in the Johnston orchard, where the fruit of the nitrogen 

 plots was left on the trees until it reached approximately the same 

 stage of maturity as that on the checks when they had been picked. 

 The difference in the dates of picking, which corresponded closely with 

 the dela}' in maturity, was exactly 3 weeks — from September 28 to 

 October 19. And w^hen the final picking was done, the amount and 

 brightness of the color on the nitrate plots was actually greater than 

 it had been on the checks. The average increase in color on the 

 treated plots, 2, 8 and 6, over the checks, 1, 4 and 7, was actually as 

 great as 10.3 per cent. The great importance of maturity on the 

 trees in increasing color is thus clearly shown. 



The importance of sunlight, we had already determined in an 

 earlier experiment. In it, we found that after the apples were picked, 

 exposure to sunlight increased their redness by 35 per cent, while 

 the checks in the dark and those exposed to electric light showed no 

 definite increase. 



We may also mention the facts that color may be materially af- 

 fected by certain kinds of spraying and by internal variations such 

 as appear in the solid-colored variants from the Gravenstein and 20- 

 ounce. These points also are discussed in our Annual Eeport for 

 1910-11, but space is too limited for further consideration here. 



RELATION OF FERTILIZATION TO SIZES 



Again referring to Tables V and VI, we see that nitrates have ap- 

 parently reduced the average size of the fruit. Phosphates have 

 given only a slight benefit, if any; while potash and manure have 

 given quite important increases. This apparent benefit from potash 

 is interesting, and it may indicate an actual fact, since size depends 

 upon moisture and potash has been credited physiologically with the 

 ability of increasing the osmotic power of plant cells. 



All these apparent influences on fruit-size, however, must be con- 

 sidered in their relation to the size of the crop on the trees. A year 

 ago, we plotted a number of curves from data given in connection 

 with a fertilizer experiment at the New Jersey Station, in order to 

 determine definitely, if possible, whether any relation existed between 

 these two factors, — fruit-size and size of the crop on the tree. We 

 found that no correlation exists below what we may call a certain 

 critical point, and that, under the New Jersey conditions, the number 

 of fruits on even moderate-sized trees had to exceed about 1,400 per 

 tree before any perceptible correlation appeared. Above this critical 

 point, however, it is probable that crop-size is the dormant influence 

 on the size of the fruit, though the exact position of the critical point 

 may doubtless be raised or lowered somewhat by local conditions 

 of moisture, plant food, etc. 



