The most obvious effect of N fertilization, and one of the most important, was on the color/appearance of the upper surface of needles. As noted earlier, considerable variation has been observed in foliage color of trees in experimental and grower-owned plantations of the Canaan Valley origin of balsam fir. In all of the studies reported here, N fertilization consistently improved the appearance of the upper surfaces of needles. For the plots established in 1993, those differences were statistically significant (except for Pomerene 1 in 1996) for unfertilized as compared to fertilized trees (Tables 4 and 7); however, differences between trees that received different levels of nitrogen (100, 200, or 300 pounds per acre) were not statistically significant. For the studies established in 1996, despite the obvious improvements in color, differences between fertilized and unfertilized trees were not statistically significant. This may have been related, in part, to the fewer numbers of treatments and replications in those studies, resulting in higher error mean square values in statistical F tests.
|
Table 4. Effects of Nitrogen Fertilization on the Color of Upper Surfaces
of Needles of Trees in Studies Established in 1996. | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Fert. Level lbs/ac | Average | Range1 | ||||||||
| 1993 | 1994 | 1995 | 1996 | 1997 | 1993 | 1994 | 1995 | 1996 | 1997 | |
| ---Rating2--- | ---Rating2--- | |||||||||
| Wooster 1: Established 1993 | ||||||||||
| 0 | 3.2 | 3.1 | 3.2 | 3.1 | 3.1 | 2.5-3.5 | 1.5-4.0 | 2.0-3.5 | 1.5-4.5 | 2.5-4.0 |
| 100 | 4.2 | 4.0 | 4.2 | 3.8 | 3.5 | 2.5-4.5 | 2.5-4.5 | 3.5-5.0 | 3.0-5.0 | 2.5-4.5 |
| 200 | 4.2 | 4.0 | 4.3 | 4.1 | 3.8 | 3.5-5.0 | 2.0-4.5 | 4.0-4.5 | 2.5-5.0 | 3.0-4.5 |
| 300 | 4.2 | 4.2 | 4.2 | 3.9 | 3.7 | 2.5-5.0 | 2.0-4.5 | 3.5-5.0 | 2.5-4.5 | 2.0-4.0 |
| Avg. | 4.0 | 3.8 | 4.0 | 3.7 | 3.5 | - | - | - | - | - |
| pF3 | 0.02 | 0.01 | 0.01 | 0.02 | 0.01 | - | - | - | - | - |
| LSD4 | 0.61 | 0.33 | 0.29 | 0.5 | 0.36 | - | - | - | - | - |
| Pomerene 1: Established 1993 | ||||||||||
| 0 | 3.2 | 3.2 | 3.1 | 3.5 | 3.2 | 2.0-4.0 | 2.5-4.0 | 1.5-4.0 | 2.5-4.5 | 2.0-4.5 |
| 100 | 4.0 | 3.8 | 3.7 | 3.9 | 3.6 | 2.5-4.5 | 2.0-4.5 | 1.5-4.5 | 2.5-4.5 | 2.5-4.0 |
| 200 | 4.2 | 4.0 | 3.8 | 4.1 | 3.8 | 2.5-4.5 | 2.5-5.0 | 2.5-4.5 | 2.5-4.5 | 3.0-4.5 |
| 300 | 4.2 | 4.2 | 3.8 | 3.9 | 3.7 | 2.0-5.0 | 2.5-4.5 | 2.5-4.5 | 2.5-4.5 | 2.5-4.5 |
| Avg. | 3.9 | 3.8 | 3.6 | 3.9 | 3.6 | - | - | - | - | - |
| pF3 | 0.01 | 0.04 | 0.01 | 0.07 | 0.07 | - | - | - | - | - |
| LSD4 | 0.39 | 0.55 | 0.37 | - | 0.38 | - | - | - | - | - |
| 1 Range in upper surface needle color for all individual
trees in each fertility treatment (4 reps x 10 trees /plot).
2 Upper Surface Needle Color Ratings: 1.0 = Yellow; 2.0 = Green-Yellow; 3.0 = Yellow-Green; 4.0 = Green; 5.0 = Blue-Green 3 pF: Probability of statistical significance for analysis of variance F test. 4 LSD: Least significant difference at 5% probability level for comparing differences between treatment means. | ||||||||||
The average foliage color of unfertilized trees was in the 3.0 to 3.5 yellow-green range, with the largest improvement for the two studies that were established in 1993 (Wooster 1 and Pomerene 1) and the least improvement on the "wettest" site, Pomerene 3.
In soil-site studies with trees of the Canaan Valley seed source of balsam fir, average foliage colors of unfertilized trees on 10-tree plots (evaluated in the same manner as trees in these studies) ranged from 1.0 (yellow) to 4.1 (green), with poorest colors for trees on "wetter" sites or in those plantings having poor weed control, and best colors were for those on better-drained areas having good weed control (unpublished data).
Although there were relatively large differences in the "average" foliage color of fertilized and unfertilized trees (note that averages for the seven to 10 trees in individual study plots were used as items in statistical analyses), there was still a wide range in the color of individual trees within plots (Tables 4 and 7), with some of the best trees on unfertilized plots having color ratings that were as good as those for trees that had been fertilized. Some of those differences were probably related to variations in internal soil drainage within and between plots in individual studies (Table 1). It is also probable that some of the differences were related to natural genetic variation. There is a wide range in the foliage color/appearance of trees in native stands of balsam fir in Canaan Valley and the other three areas in West Virginia where the species is found. In replicated studies at OARDC on a site near the Pomerene Forest Laboratory, there are statistically significant differences in needle colors and other traits (growth rates, needle lengths, form, density, etc.) of trees grown from seed collected from individual mother trees (half-sib families) in the different West Virginia stands. Genetic selection of individual progeny from specific locations, half-sib families, and/or individual trees will be needed to further enhance overall appearance of the foliage of trees.