48 



as late picking, light soils, open pruning, and sod culture will in- 

 crease color. Opposite conditions decrease it. 



From this viewpoint, the reduction in color caused by the ni- 

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

 delayed maturity. That such is the case was shown the past sea- 

 son, especially in the Johnston orchard, where the fruit of the nitro- 

 gen 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 cor- 

 respond closely with the delay in maturity, was exactly three weeks. 

 — from September 28th to October 19th. And when the final pick- 

 ing 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. 3 and 6, over the 

 checks, I, 4 and 7, was actually as great as 10.3 per cent. The great 

 importance of maturit}' 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. 



\A^e may also mention the facts that color may be materially 

 aff'ected 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 Report 

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



Relation of Fertilization to Size. 



Again referring to Tables A' and we see that nitrates have 

 apparently 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 

 so much 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 

 considered 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 connec- 

 tion with a fertilizer experiment at the Xew Jersey Station, in 

 order to determine definitely, if possible, ^^'hether any relation exist- 

 ed betAveen 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 Xew Jersey conditions, the 

 number of fruits on even moderate-sized trees had to exceed about 

 1400 per tree before any perceptible correlation appeared. Above 

 this critical point, however, it is probable that crop-size is tJie dor- 

 mant influence on the size of the fruit, though the exact position of 

 the critical point may doubtless be raised or lowered somewhat by 

 lo^al conditions of moisture, plant food, etc. 



