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T.E. Thompson and J.F. Baker

Heritability estimates for pecan [Carya illinoinensis (Wangenh.) K. Koch] nut weight, nut buoyancy, nut volume, nut density, kernel weight, and percentage kernel were determined from 8748 nut samples representing 152 families collected during 25 years in the U.S. Dept. of Agriculture (USDA) pecan breeding program at Brownwood, Texas. Measurements were corrected for year-to-year environmental variability using least-squares constants of individual year effects. Adjusted values were then regressed on midparent means. Generally, heritability (h2) estimates were low to moderate: nut weight 0.35, nut buoyancy 0.18, nut volume 0.35, nut density 0.03, kernel weight 0.38, and percentage kernel 0.32. The low values are probably due to the extreme alternate bearing tendency of this species, since crop load affects pecan nut characteristics so directly. Phenotypic correlations among these traits showed that larger or heavier nuts had significantly higher kernel weight, buoyancy, and percentage kernel. Nut density increased with higher nut and kernel weight, but decreased with nut volume.

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Jesse Vorwald and James Nienhuis

phenotypic correlation among traits was observed between PopPct and CoE; the magnitude of the corresponding additive genetic correlation was similar in sign and magnitude ( Table 3 ). PopPct and CoE were not significantly correlated with seed weight. These

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Luping Qu, Ying Chen, Xiping Wang, Richard Scalzo, and Jeanine M. Davis

We investigated patterns of variation in alkamides and cichoric acid accumulation in the roots and aboveground parts of Echinacea purpurea (L.) Moench. These phytochemicals were extracted from fresh plant parts with 60% ethanol and quantified by high performance liquid chromatography (HPLC) analysis. Concentrations of alkamides and cichoric acid were measured on a dry-weight basis (mg·g–1). For total alkamides, concentrations among individual plants varied from 5.02 to 27.67 (mean = 14.4%) in roots, from 0.62 to 3.42 (mean = 1.54) in nearly matured seed heads (NMSH), and 0.22 to 5.25 (mean = 0.77) in young tops (about ½ flower heads, ¼ leaves, and ¼ stems). For cichoric acid, concentrations among individual plants varied from 2.65 to 37.52 (mean = 8.95), from 2.03 to 31.58 (mean = 10.9), and from 4.79 to 38.55 (mean = 18.88) in the roots, the NMSH, and the tops, respectively. Dodeca-2E, 4E, 8Z, 10E-tetraenoic acid isobutylamide and dodeca-2E, 4E, 8Z, 10Z-tetraenoic acid isobutylamide (alkamides 8/9) accounted for only 9.5% of the total alkamides in roots, but comprised 87.9% in the NMSH, and 76.6% in the young tops. Correlations of concentrations of alkamides or cichoric acid between those of roots and those of the NMSH were not statistically significant, and either within the roots, the NMSH, and the young tops. However, a significant negative correlation was observed between the concentration of cichoric acid in the roots and in young tops, and a significant positive correlation was observed between total alkamide concentration in the roots and cichoric acid concentration in the young tops. These results may be useful in the genetic improvement of E. purpurea for medicinal use.

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Shufu Dong, Denise Neilsen, Gerry H. Neilsen, and Michael Weis

A simple flatbed-scanner-based image acquisition system was developed for the measurement of `Gala'/M9 (Malus ×domestica Borkh.) apple tree root growth in rhizoboxes with a transparent acrylic sheet on one side. A tree was planted in the center of each rhizobox, and a modified flatbed scanner was periodically used to directly capture high-resolution digital images of roots growing against the transparent wall. Total root length in the images was either measured manually, or by computer mouse tracing, or automatically with a computer image analysis system. Correlations were made among the different measurements. High quality root images were obtained with the adapted scanner system. Significant linear relationships were found between manual and computer traced root length measurements (r = 0.99), traced and automatic measurements (r = 0.76) and manual and automatic measurements (r = 0.75). Apple roots appeared on the transparent wall 34 days after transplanting, and grew rapidly thereafter, reaching a maximum on the transparent wall 59 days after transplanting. Our results showed that the use of a flatbed scanner for the acquisition of root images combined with computer analysis is a promising technique to speed data acquisition in root growth investigations.

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A. Golmirzaie and F. Serquen

A field experiment was conducted at two locations to determine the correlation between seedling and mature plant characters in a large potato (Solanum tuberosum) population developed for production from true potato seed. There was no significant correlation between seedling and reproductive characters, including earliness, at the two locations. Number of internodes and yield per plant were significantly correlated at Huancayo, and at San Ramon, root length and hypocotyl length had a significant correlation with the number of tubers per plant and yield per plant. Although significant, the latter correlations are not high enough to be used to predict the final behavior of genotypes by their seedling traits. Thus, it may be assumed that a certain independence between seedling and mature plant growth characters exists.

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Christopher S. Cramer and Todd C. Wehner

The relationships between fruit yield and yield components in several cucumber (Cucumis sativus L.) populations were investigated as well as how those relationships changed with selection for improved fruit yield. In addition, the correlations between fruit yield and yield components were partitioned into partial regression coefficients (path coefficients and indirect effects). Eight genetically distinct pickling and slicing cucumber populations, differing in fruit yield and quality, were previously subjected to modified half-sib family recurrent selection. Eight families from three selection cycles (early, intermediate, late) of each population were evaluated for yield components and fruit number per plant in four replications in each of two testing methods, seasons, and years. Since no statistical test for comparing the magnitudes of two correlations was available, a correlation (r) of 0.7 to 1.0 or –0.7 to –1.0 (r 2 ≥ 0.49) was considered strong, while a correlation of –0.69 to 0.69 was considered weak. The number of branches per plant had a direct positive effect on, and was correlated (r = 0.7) with the number of total fruit per plant over all populations, cycles, seasons, years, plant densities, and replications. The number of nodes per branch, the percentage of pistillate nodes, and the percentage of fruit set were less correlated (r < |0.7|) with total fruit number per plant (fruit yield) than the number of branches per plant. Weak correlations between yield components and fruit yield often resulted from weak correlations among yield components. The correlations among fruit number traits were generally strong and positive (r ≥ 0.7). Recurrent selection for improved fruit number per plant maintained weak path coefficients and correlations between yield components and total fruit number per plant. Selection also maintained weak correlations among yield components. However, the correlations and path coefficients of branch number per plant on the total fruit number became more positive (r = 0.67, 0.75, and 0.82 for early, intermediate, and late cycles, respectively) with selection. Future breeding should focus on selecting for the number of branches per plant to improve total fruit number per plant.

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Yiwei Jiang, Robert N. Carrow, and Ronny R. Duncan

Traffic stresses often cause a decline in turfgrass quality. Analysis of spectral reflectance is valuable for assessing turfgrass canopy status. The objectives of this study were to determine correlations of narrow band canopy reflectance and selected reflectance indices with canopy temperature and turf quality for seashore paspalum exposed to wear and wear plus soil compaction traffic stresses, and to evaluate the effects of the first derivative of reflectance and degree of data smoothing (spectral manipulations) on such correlations. `Sea Isle 1' seashore paspalum (Paspalum vaginatum Swartz) was established on a simulated sports field during 1999 and used for this study. Compared to original reflectance, the first derivative of reflectance increased the correlation coefficient (r) of certain wavelengths with canopy temperature and turf quality under both traffic stresses. Among 217 wavelengths tested between 400 and 1100 nm, the peak correlations of the first derivative of reflectance occurred at 661 nm and 664 nm for both canopy temperature and turf quality under wear stress, respectively, while the highest correlations were found at 667 nm and 820 to 869 nm for both variables under wear plus soil compaction. Collectively, the first derivative of reflectance at 667 nm was the optimum position to determine correlation with canopy temperature (r > 0.62) and turf quality (r < -0.72) under both traffic stresses. All correlations were not sensitive to degrees of smoothing of reflectance from 400 to 1100 nm. A ratio of R936/R661 (IR/R, Infrared/red) and R693/759 (stress index) had the strongest correlations with canopy temperature for wear (r = -0.63) and wear plus soil compaction (r = 0.66), respectively; and a ratio of R693/R759 had the strongest correlation with turf quality for both wear (r = -0.89) and wear plus soil compaction (r = -0.82). The results suggested that the first derivative of reflectance could be used to estimate any single wavelength simultaneously correlated with multiple turf canopy variables such as turf quality and canopy temperature, and that the stress index (R693/R759) was also a good indicator of canopy stress status.

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Keith Woeste, Gale McGranahan, and Robert Bernatzky

A first backcross population of walnuts {[Juglans hindsii (Jeps.) Jeps. × Juglans regia L.] × J. regia} was used to evaluate the correlation between morphological (statistical) and genetic distance during introgression. Five traits based on leaf morphology were identified to quantitate the morphology of the parental species, their F1 hybrids, and the backcrosses to each parent. These traits were used to evaluate the morphological similarity of first backcrosses to J. regia using Mahalanobis' distance. The amount of genomic introgression of each backcross was estimated using 59 randomly amplified polymorphic DNA (RAPD) and 41 restriction fragment-length polymorphism (RFLP) genetic markers that identify polymorphisms between J. regia and J. hindsii. A smaller scaffold set of markers was also identified using published linkage data. The correlation between the measures of morphological and genomic introgression for the first backcrosses was low (0.23) but significant. The results suggest that selection based on morphology during backcrossing will not be an effective way to recover recurrent parent genome.

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Chiwon W. Lee, Chun-Ho Pak, and Jong-Myung Choi

Correlations between the nutrient solution concentration and tissue content of micronutrients were determined for geranium, marigold and petunia. When nutrient solution contained 0.25, 0.5, 1, 2, 3, 4, 5, 6 mM of boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn), the tissue content of each microelement increased linearly with increasing levels of the same micronutrient in the fertilizer. Equations for these correlations were established for the six micronutrients used for each species. Increasing levels of micronutrients did not influence tissue macroelement contents. Increasing levels of one micronutrient had little influence on the accumulation of other micronutrients in the tissue. Plant toxicity symptoms developed when the leaf content of microelements increased to a level 5-10 times that of plants grown with the control (Hoagland) solution.

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Thomas S.C. Li and G. Mazza

Four-year-old American ginseng (Panax quinquefolium L.) plants and soil samples were collected from nine ginseng gardens. Soil and leaf mineral contents were determined and six major ginsenosides, Rb1, Rb2, Rc, Rd, Re, and Rg1, were extracted from leaves and roots and quantified by high-performance liquid chromatography (HPLC). Correlation coefficients were more significant for soil nutrient levels vs. ginsenoside contents of leaves than of roots, suggesting that soil nutrient levels may play a major role in the synthesis of leaf ginsenosides. Minor elements in the leaf were also better correlated with ginsenoside contents of the root than that of the leaf. Iron content in the leaves exhibited highly significant correlations with the levels of Rb1, Rb2, Rc, and Rd, but calcium and copper contents were negatively correlated with Rg1 in the roots.