The lower surfaces of needles of trees of balsam fir typically have several rows of stomata resulting in varying degrees of a "bluish" or "bluish-white" appearance. For Fraser fir, the lower surfaces of needles usually have a pronounced bluish appearance, while for many of the more northerly origins (var. balsamea) there is only a faint bluish color. For trees sampled in these studies, N fertilization consistently improved the bluish appearance of the lower surfaces of needles; however, none of those differences was statistically significant (Tables 5 and 7).
For unfertilized trees, color ratings for needles on the three wetter sites (Wooster 1 and 2 and Pomerene 3) averaged in the "slightly bluish" category (ratings of 1.2 to 1.4), with color improving to the "moderately bluish" category (ratings of 1.6 to 2.0) for fertilized trees. On the two better drained sites (Pomerene 1 and 2), ratings for unfertilized trees were closer to the "moderately bluish" category (ratings of 1.6 to 1.9), while fertilized trees were only slightly improved (ratings of 1.8 to 2.3).
Although not tabulated in Tables 5 and 7, there was also a wide range in the color of the lower surfaces of needles between individual trees within and between plots such as was noted for the upper surfaces. Also, as discussed previously for the upper surfaces of needles, there are genetic differences in lower-surface colors related to between and within half-sib families from different areas.
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Table 5. Effects of Nitrogen Fertilization on the Color of the Lower Surfaces of Needles
and Foliar Nitrogen Levels of Trees in Studies Established in 1993. | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Fert. Level lbs/ac | Lower Surface of Needle Color | Needle N Content | ||||||||
| 1993 | 1994 | 1995 | 1996 | 1997 | 1993 | 1994 | 1995 | 1996 | 1997 | |
| ---Rating1--- | ---Percent--- | |||||||||
| Wooster 1: Established 1993 | ||||||||||
| 0 | 1.3 | 1.3 | 1.2 | 1.3 | 1.4 | 1.35 | 1.33 | 1.33 | 1.30 | 1.24 |
| 100 | 1.9 | 1.6 | 1.8 | 1.6 | 1.8 | 2.01 | 1.66 | 1.63 | 1.54 | 1.63 |
| 200 | 1.7 | 1.7 | 2.0 | 1.8 | 1.9 | 2.15 | 1.73 | 1.81 | 1.61 | 1.59 |
| 300 | 1.7 | 1.6 | 1.6 | 1.7 | 1.9 | 2.04 | 1.75 | 1.73 | 1.68 | 1.70 |
| Avg. | 1.6 | 1.5 | 1.6 | 1.6 | 1.8 | 1.99 | 1.62 | 1.63 | 1.53 | 1.54 |
| pF2 | 0.14 | 0.21 | 0.15 | 0.74 | 0.20 | 0.14 | 0.01 | 0.03 | 0.23 | 0.03 |
| LSD3 | - | - | - | - | - | - | 0.23 | 0.30 | - | 0.35 |
| Pomerene 1: Established 1993 | ||||||||||
| 0 | 1.8 | 1.7 | 1.9 | 1.7 | 1.7 | 1.89 | 1.86 | 1.93 | 1.77 | 1.60 |
| 100 | 2.0 | 1.9 | 2.1 | 1.8 | 1.9 | 1.95 | 1.95 | 1.99 | 1.98 | 1.85 |
| 200 | 2.1 | 1.9 | 2.2 | 1.8 | 2.0 | 2.15 | 1.96 | 2.09 | 1.90 | 1.75 |
| 300 | 2.2 | 1.9 | 2.3 | 1.8 | 2.0 | 2.18 | 1.93 | 2.15 | 2.05 | 1.83 |
| Avg. | 2.0 | 1.9 | 2.1 | 1.8 | 1.9 | 2.04 | 1.93 | 2.04 | 1.93 | 1.76 |
| pF2 | 0.14 | 0.22 | 0.08 | 0.27 | 0.11 | 0.01 | 0.18 | 0.01 | 0.05 | 0.04 |
| LSD3 | - | - | - | - | - | 0.12 | - | 0.11 | 0.17 | 0.16 |
| 1 Lower Needle Surface Color Ratings: 1 = Slightly Bluish; 2 = Moderately Bluish; 3 = Bluish.
2 pF: Probability of statistical significance for analysis of variance F test. 3 LSD: Least significant difference at 5% probability level for comparing differences between treatment means. | ||||||||||
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Table 6. Effects of Nitrogen Fertilization on Shoot and Needle Lengths and Foliage Weights of Trees in Studies Established in 1996. | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Fert. Level lbs/ac | Shoot Growth | Needle Length | Foliage Weight | Lateral Limbs | |||||
| 1996 | 1997 | 1996 | 1997 | 1996 | 1997 | 1996 | 1997 | ||
| ---cm--- | ---mm--- | ---gms--- | ---no.--- | ||||||
| Wooster 2: Established 1996 | |||||||||
| 0 | 21 | 30 | 14 | 17 | 1.03 | 0.96 | 17 | 16 | |
| 100 | 26 | 36 | 15 | 18 | 1.25 | 1.19 | 19 | 18 | |
| 200 | 24 | 37 | 15 | 17 | 1.31 | 1.28 | 18 | 19 | |
| Avg. | 24 | 33 | 15 | 17 | 1.19 | 1.14 | 18 | 18 | |
| pF1 | 0.54 | 0.22 | 0.80 | 0.72 | 0.31 | 0.38 | 0.78 | 0.62 | |
| LSD2 | - | - | - | - | - | - | - | - | |
| Pomerene 2: Established 1996 | |||||||||
| 0 | 41 | 53 | 19 | 21 | 1.25 | 1.16 | 30 | 24 | |
| 100 | 39 | 52 | 20 | 21 | 1.36 | 1.31 | 29 | 25 | |
| 200 | 38 | 54 | 20 | 21 | 1.35 | 1.29 | 28 | 23 | |
| Avg. | 39 | 52 | 20 | 21 | 1.32 | 1.25 | 29 | 24 | |
| pF1 | 0.79 | 0.86 | 0.82 | 0.91 | 0.17 | 0.08 | 0.80 | 0.72 | |
| LSD2 | - | - | - | - | - | - | - | - | |
| Pomerene 3: Established 1996 | |||||||||
| 0 | 33 | 38 | 17 | 16 | 1.00 | 0.94 | 26 | 25 | |
| 100 | 31 | 45 | 18 | 18 | 1.19 | 1.10 | 32 | 25 | |
| 200 | 30 | 45 | 18 | 19 | 1.16 | 1.10 | 27 | 25 | |
| Avg. | 31 | 43 | 18 | 18 | 1.12 | 1.05 | 29 | 25 | |
| pF1 | 0.74 | 0.51 | 0.81 | 0.80 | 0.21 | 0.12 | 0.60 | 0.90 | |
| LSD2 | - | - | - | - | - | - | - | - | |
| 1 pF: Probability of statistical significance for analysis of variance F test.
2 LSD: Least significant difference at 5% probability level for comparing differences between treatment means. | |||||||||