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- Author or Editor: W. H. Swallow x
Tuberization response, average number of tubers produced per tuberized plant, total tuber yield, average tuber weight, and average tuber specific gravity were measured for six diploid potato clones grown under long and short day conditions at 22°/18°C and 18°/14° in the phytotron. Average number of tubers and total tuber yield were significantly greater under short days than under long days. Significant temperature × photoperiod interactions were found for these two variables. Lack of significant photoperiod, temperature, and photoperiod × temperature effects on average tuber weight suggests that significant increases in average yield occur due to an increase in the average number of tubers produced and not to an increase in the size of individual tubers. Average tuber specific gravities were significantly greater at 18°/14° than 22°/18°. A significant temperature × photoperiod interaction was found for this variable.
One-year-old crowns of Asparagus officinalis L. cv. Princeville were grown for up to 2 years in pots containing a mineral soil. Nitrogen concentrations ranged from O to 340 kg N/ha. Increasing N fertilizer level resulted in a decrease in total crown fructose concentration and an increase in fern growth, both leveling off at higher N levels. Crown growth was maximized at intermediate N levels. To obtain maximum crown growth and total fructose concentration, while avoiding the excessive fern growth associated with higher N fertilizer levels, ≈57 kg N/ha should be applied to asparagus during the 2nd and 3rd years of growth.
Mature-green `Grande Naine' bananas (Musa AAA) were harvested 13 weeks after flowering, in June and Sept. 1993, and Feb. and Mar. 1994. Fruit were 1) held in storage for 36 days at 14C and 80% to 90% RH, or 2) after 8 days of storage, fruit were treated with ethylene, and held at 17C until color 6 of the standard color scale was observed. Although a similar grade and age, the length of the preclimacteric phase was different among months, which reflected different physiological maturities at harvest. Rate of respiration, pulp pH, and soluble solids were the most-useful variables to characterize the fruit. Increases in respiration after ethylene treatment varied from 4- up to 14-fold the respiratory level under storage conditions. The climacteric occurred at any point during ripening, ranging from color 2 to 5, except at very early stages. Ethylene increases were short in duration and magnitude, and occurred earlier than the respiratory peak. Sometimes, internal and external ripening stages did not match. The most dramatic seasonal effects were observed in CO2 evolution, pulp-to-peel ratio, and starch conversion.
Mature-green `Grande Naine' bananas from Costa Rica, Mexico, Ecuador, and Guatemala were harvested in June, Sept., and Dec. 1993 and Mar. 1994. Fruit were treated with ethylene and held at 17C and 80% to 90% relative humidity until they reached color 6 of the standard color scale. Guatemalan bananas had the highest respiration rate, followed by Costa Rican, Mexican, and Ecuadoran fruit. Peel color, ethylene production, and soluble solids content did not differ among the countries. Measurements made at arrival in the United States had a low correlation with days to reach color 5. Prediction equations showed significant linear relationships for most variables; however, correlations were very low. The highest coefficient of determination was observed with respiration rate (r 2 = 0.289). Maximum R 2 (0.342) was determined using CO2, C2H4, pH, and soluble solids in the model. pH and soluble solids were good variables to determine the physiological stage of the fruit, and they also detected ripening changes earlier than peel color or firmness.
Fruit, stems, tendrils, leaves, and leaf petioles of4Noble’ muscadine grape (Vitis rotundifolia Michx.) were analyzed using high performance liquid chromatography (HPLC) techniques. All five of the known 3,5-diglucoside forms of delphinidin (Dp), cyanidin (Cy), petunidin (Pt), peonidin (Pn), and malvidin (Mv) present in fruit of muscadine grape were detected in all sampled tissues except leaves, which contained only Dp, Cy, and Pt in detectable quantities. A sixth unknown pigment was detected in the fruit, and Dp 3-monoglucoside was detected in the leaves. Correlations were calculated to explore pigment relationships between fruit and vegetative tissues. Use of tendrils was best for predicting fruit Cy (r = 0.60), Mv (r = 0.57), Pn (r = 0.66), and Pt (r = 0.87). Use of stem tissue was best for predicting fruit Dp (r = 0.66). Prediction equations are given, and prediction of Cy could be improved by using both tendril and leaf measurements in a multiple regression (r = 0.80).
Fruit, stem, tendril, leaf, and leaf petioles of 10 selections of muscadine grape (Vitis rotundifolia Michx.) were evaluated for pigment quantity and quality using high performance liquid chromatography (HPLC). All five of the 3,5-diglucoside pigments present in the fruit were present in detectable levels in the other four tissues of at least one selection except for leaves, which lacked peonidin (Pn) in all cases. Eight selections lacked detectable quantities of malvidin (Mv) in the leaves, one lacked Pn in stems, and six lacked Pn in leaf petioles. A sixth unknown pigment was detected in the fruit of two selections, and delphinidin (Dp) 3-monoglucoside was detected in leaves of all 10 selections. Fruit to vegetative tissue correlation and significance values were calculated across genotypes, with r ranging from 0 for fruit to leaf Mv to 0.53 for fruit to leaf petiole Dp. Stepwise regression analysis determined that leaf petiole and leaf tissue measurements together could predict fruit Dp better than could leaf petiole measurements alone (R = 0.80, significant at Ρ = 0.03; and R = 0.53, significant at Ρ = 0.11, respectively), and fruit petunidin (Pt) could be predicted from leaf petiole and stem measurements better than from leaf petiole measurements alone (R = 0.68, significant at Ρ = 0.12; and R = 0.40, significant at Ρ = 0.25, respectively).
Vaccinium species collected from the eastern United States were grown and fruited at Castle Hayne, N.C. Harvest season extended from 5 June to 22 Aug. Vaccinium angustifolium Ait. was earliest ripening. Vaccinium myrtilloides Michx., V. elliotti Chap., diploid V. corymbosum L., and tetraploid V. pallidum Ait. populations also contained very early- to early-ripening seedlings. Early-ripening seedlings were not observed in tetraploid V. corymbosum populations and reached peak ripeness around mid-June, about with ‘Bluecrop’. One tetraploid V. corymbosum population continued ripening into early August. Vaccinium ashei Reade populations from Georgia began ripening about 2 weeks earlier than Florida V. ashei or Arkansas V. amoenum Ait. populations. One Georgia V. ashei population was only slightly later than tetraploid V. corymbosum. The Florida V. ashei populations continued ripening into late August. The diploid species V. darrowi Camp, V. tenellum Ait., and V. stamineum L., were all basically late in ripening. The potential utility of these species in breeding for both early- and late-ripening Vaccinium genotypes is discussed.
Eleven species in sections Cyanococcus and Polycodium of the genus Vaccinium were compared among themselves and with standard cultivars for soluble solids, titratable acidity, soluble solids/acid ratio, weight/berry (g), stem scar diameter (pedicel diameter at the berry), scar depth, fruit removal force (picking ease), and firmness. Vaccinium ashei Reade populations collected in either Florida or Georgia showed consistent differences in acidity, fruit size, and firmness. No such pattern in geographical differences occurred with V. corymbosum L. Vaccinium stamineum L. (section Polycodium) was outstanding for high soluble solids, large fruit size, small scar diameter, and firmness. Vaccinium elliottii Chapm. seemed promising for mechanical harvesting and processing with high-acid fruit, a favorable soluble solids/acid balance, small scar diameter, and easily harvested fruit. Vaccinium angustifolium Ait. was noted for high soluble solids, small shallow scar, and picking ease; V. pallidum Ait. for high soluble solids and small shallow scar; V. amoenum Ait. for small shallow scar and picking ease; and tetraploid V. corymbosum for high acidity and favorable soluble solids/acid balance. Sufficient variability occurred among and within species for selection for improvement of most traits; however, several generations of backcrossing or recurrent selection would be required for producing genotypes with commercial fruit size.
Decline in sweetpotato yield and storage root quality has been attributed to the accumulation of viruses, pathogens and mutations. To document the effects of decline on yield and storage root quality, two micropropagated, virus-indexed, greenhouse produced G1 `Beauregard' meristem-tip cultured clones, B94-14 and B94-34, were compared with 1) micropropagated B94-14 and B94-34 clones propagated adventitiously up to five years in the field (G2, G3, G4, G5); and 2) nonmicropropagated, unimproved stock of `Beauregard' seed in field trials during 1997 to 2001. At least three trials were located each year in sweetpotato producing regions in North Carolina. In 2000 and 2001, two trials were monitored weekly for foliar symptoms of Sweet potato feathery mottle virus (SPFMV) and other potyviruses, and virus-indexed for selected viruses using Ipomoea setosa and nitrocellulose enzyme linked immunosorbant assays (NCM-ELISA). Only SPFMV was detected in field samples using NCM-ELISA, but this does not rule out the presence of newly described viruses infecting sweetpotato for which tests were unavailable. Monitoring indicated that all G1 plants became infected with SPFMV by the end of the growing season, and that G2 to G5 plants were probably infected in their initial growing season. G1 plants consistently produced higher total yield, total marketable yield (TMY), U.S. No. 1 root yield and percent No. 1 yield than G2 to G5 plants. G1 plants also produced storage roots with more uniform shapes and better overall appearance than storage roots produced from G2 to G5 plants. Also, G2 to G5 storage roots tended to be longer than G1 storage roots. Rank mean yield and storage root quality measurements of each location were consistent with means averaged over locations per year and suggested a decrease in yield and storage root quality with successive seasons of adventitious propagation. Linear regression analysis used to model yield and storage root quality measurements of seed generations G1 to G5 indicated that total yield, TMY, No. 1 yield, percent No. 1 yield, shape uniformity, and overall appearance decreased gradually, and that length/diameter ratios increased gradually with generation. The rate of decline in No. 1 yield was greater for B94-34 compared to B94-14. Both viruses and mutations of adventitious sprouts arising from storage roots probably contribute to cultivar decline in sweetpotato, but further studies are needed to determine their relative importance. A simple profitability analysis for G1 vs. G2-G4 planting material conducted to facilitate better understanding of the economics of using micropropagated planting material to produce a crop in North Carolina revealed that growers have a potential net return of $2203/ha for G1 plants, $5030/ha for G2 plants, and $4394/ha for G5 plants. Thus, while G1 plants generally produce higher No. 1 yields, a greater monetary return can be achieved using G2 planting materials because of the high costs associated with producing G1 plants. Based on this analysis, the best returns are accrued when growers plant their crop using G2 and/or G3 seed.