382 ANNUAL REPORT OF THE Off. Doc. 



CORRELATION BETWEEN YIELD AND GROWTH 



In regard to growth, it will be observed that, in general the im- 

 provements in it have accompanied those in yield. The same ma- 

 terials that have improved the one have generally improved the 

 other. In other words, as a rule, our best growing plots have been 

 our best fruiting plots. Contrary to a prevalent notion, therefore, 

 we may say that growth and fruiting are not necessarily antagonis- 

 tic, but rather are associated, unless either should occur in abnormal 

 amount. 



DATA AND DEDUCTIONS ON COLOR 



In regard to color, it will be observed in Tables V and V[ that 

 none of the applications have given any important increases, and 

 most of them have given decreases. Similar results have also been 

 uniformly obtained elsewhere, so far as we have received the re- 

 ports. The same is essentially true of applications of iron salts. 

 From these and other considerations, therefore, we belie\e that color 

 in apples cannot be materially improved by soil applications, and 

 that it is primarily dependent on maturity and sunlif/ht. 



This refers only to the red colors in apples. The yellow colors 

 can probably not be affected by any external agency. Physiologi- 

 cally, the yellow color is connected with certain bodies located in 

 the superficial layers of cells in the apple skin. It develops inde- 

 pendent of light, and its intensity depends merely upon the degree 

 of maturity or ripeness. The red color, on the other hand, is a 

 constituent of the cell sap ; it is capable of being influenced by a 

 number of agencies ; 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 dependence upon maturity and 

 sunlight. Conditions increasing one or both of these factors, such 

 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 fo 

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

 son, especially in the Johnston orchard, where the frmlt 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 correspond 

 closely with the delay in maturity, was exactly three weeks, — 

 from September 28th to October IDth. 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 G. 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 incr^easing color is thus 

 clearly shown. 



The importance of sunlight, we had already determined in an 

 earlier expeiiment. In it, we found that after the ar)])les 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 

 affected by certain kinds of spraying and by internal variations such 



