Munsell color charts to record colors. The Munsell system classifies any existing 

 color on the basis of three attributes: hue, value and chroma, as was previously 

 explained in Section I describing the work on the Main Plots. To summarize: 



Hue in Christmas trees is the location of needle color in relation to yellow 

 on one end of the scale and blue on the other. Balsam needles tend to fall in the 

 5 GY (a yellow-green 50-50 mix) or 7.5 GY slot, somewhat more toward the 

 green category. A move toward the blue range in hue was considered a color 

 improvement in this study. 



Value in color indicates its lightness, and a decrease in value scale or darkening 

 of the color was considered an improvement. 



Chroma in a color is its purity or intensity. It is also described as its strength, 

 or departure from neutral. It was pointed out Section 1, an approach toward 

 gray (less pure of intense) might not detract from the appearance of a Christmas 

 tree if the hue and value characteristics are pleasing. A lower reading in chroma 

 indicates more gray. 



A numerical code was developed for computer analysis of color changes 

 The use of the Munsell system allowed a more objective approach to color rating, 

 but there are weaknesses in matching colors in the field. It soon became 

 apparent that it is easier to be aware of color differences in the field just by 

 looking at trees than it is to locate the obvious difference on the color charts. In 

 other words, the charts are not as "sensitive" or discriminating among small 

 differences in color as is the eye. Also, changes in lighting with time of day 

 and season affected the reaction of the observers. Finally, the reaction of one 

 observer may differ from that of another. With these limitations admitted, the 

 chart system was the only objective way available to rate color. 



Hue is probably the most fundamental color characteristic related to 

 Christmas tree quality. Hue changes that developed during 1966 cannot be said 

 to be definitely due to treatment, but changes were discernible under the rating 

 system employed. There was a measured movement toward the blue range 

 through application of Comp. low, Comp. high, P low, N low and K low. An 

 orthogonal test between control trees and individual treatments indicated 

 significant differences between Comp. low and control trees with an improve- 

 ment in tree color toward blue. The Mg low treatment resulted in a significant 

 shift in tree color toward yellow. 



Value changes (lightening or darkening) are significantly affected by the 

 fertilizer treatments. Comp. low treatment was again excellent, darkening the 

 needles. N low also recorded a significant improvement over the control. N 

 high and Comp. high darkened color but not as positively as Comp. low and 

 N low. Needles were significantly lightened by both levels of magnesium 

 fertilizers. 



Chroma changes were recorded but results were inconclusive. The treatment 

 that showed the greatest departure from control was Comp. low with a 

 significant shift toward the gray. 



In the fall of 1967, when plots were remeasured, the observers compared 1967 

 with the 1966 needle color. The analyses just presented were the first year 

 changes, results of 1966 relative to those of 1965. The second year comparison 



18 



