bluuebunny/crossref_metadata_2025 huggingface dataset:
Gene Expression Associated with Apple Aroma Biosynthesis
Authors: Sugimoto Nobuko , van Nocker Steve , Korban Schuyler , Beaudry Randy
Published: February 2019

A microarray containing over 10,000 gene fragments was used to link changes in gene expression with changes in aroma biosynthesis in ripening apple (Malus ×domestica Borkh). The microarray was probed with fluorescent-tagged cDNA derived from RNA extracted from `Jonagold' apple skin and cortex tissue representing eight distinct physiological stages spanning 70 days during ripening and senescence. The ripening stages, in chronological order, were: 1) early preclimacteric; 2) late preclimacteric and onset of trace ester biosynthesis; 3) onset of the autocatalytic ethylene and rapidly increasing ester biosynthesis; 4) half-maximal ester biosynthesis and engagement of the respiratory climacteric; 5) near maximal ester biosynthesis, peak in respiratory activity, and the onset of rapid tissue softening; 6) maximal ester biosynthesis prior to its decline, the conclusion of the respiratory climacteric, and the completion of tissue softening; 7) midpoint in the decline in ester biosynthesis and maximal ethylene biosynthesis; and 8) postclimacteric minimum in ester production. Patterns in gene expression reflecting the rise and fall in ester formation were found in some putative genes for beta-oxidation (acyl-CoA oxidase, enoyl-CoA hydratase, and acetyl-CoA acetyl transferase), ester formation (aminotransferase, alcohol dehydrogenase, and alcohol acyl transferase), and fatty acid oxidation (lipoxygenase), but not fatty acid biosynthetic genes. A marked decline coinciding with the onset of ester production was detected in several putative genes for ADH.
Efficacy of Sprayable 1-MCP on Apple Quality at Harvest and after Storage: The Ontario Experience
Authors: De Ell Jennifer , Murr Dennis
Published: February 2019

A sprayable formulation of 250 μL·L-1 1-MCP and 1% oil adjuvant was applied to mature `McIntosh', `Empire', and `Delicious' apple trees 1 week prior to anticipated optimum harvest. Other spray treatments included: none, 1% oil adjuvant alone, and a formulation of 125 μL·L-1 1-MCP and adjuvant (`Empire' only). Unsprayed fruit were treated postharvest with or without gaseous 1-MCP (1 μL·L-1). At harvest, internal ethylene concentration (IEC), starch index, firmness, and soluble solids concentration were measured, as well as CO2, ethylene, and total volatile production of fruit samples over a 14-day period at 22 °C. Additional fruit samples for all preharvest and postharvest 1-MCP treatments were held 14 days at 22 °C and IEC and firmness measured for treatment efficacy. Fruit quality was assessed at 3 and 6 month storage intervals and over a 2-week ripening period at 22 °C. For all cultivars, the production rates of CO2, ethylene, and volatiles, as well as increases of IEC and decreases in firmness were inhibited or delayed by sprayable 1-MCP treatment. These effects were comparable to the postharvest 1-MCP treatment and were maintained during storage. The results of these experiments suggest that sprayable 1-MCP could be an additionaal tool for maintaining apple fruit quality. However, the sprayable formulation used in this study caused 100% incidence of skin damage to `McIntosh' and a slight amount to `Empire' (<5%). Lesions were halo-like, centered around lenticels, and tended to be more severe near the calyx. No skin damage was observed in `Delicious' or in fruit treated with the adjuvant only or postharvest 1-MCP.
Interaction of Water Loss and Fruit Ripening Promote Postharvest Cluster Tomato Fruit Abscission
Authors: Brecht Jeffrey K. , Cordasco Kimberly M.
Published: February 2019

Abscission of cluster tomatoes commonly limits product marketability in the retail environment. Ripening and exogenous ethylene exposure are assumed to play important roles in cluster tomato fruit abscission. `Clarance' and `DRW7229' fruit harvested at either mature green or partially ripened stages did not abscise during storage for 2 weeks at 20 °C and 95% to 100% relative humidity (RH), although respiration and ethylene production indicated that all fruit reached the postclimacteric stage. Exogenous ethylene (1 or 10 ppm) exposure for 8 days at 20 °C and 95% to 100% RH also did not induce fruit abscission for either cultivar, although pedicel and sepal yellowing were observed. Fruit from clusters stored at 20 °C and 20% or 50% RH abscised if sepal shrivel became noticeable before the fruit reached the full red ripeness stage, while no abscission occurred in fruit that reached the full red stage prior to the appearance of sepal shrivel; no fruit stored in 95% to 100% RH abscised. Fruit that ripened prior to the appearance of sepal shrivel were “plugged” (i.e., tissue underlying the stem scar was pulled out) if manual fruit detachment from the pedicel was attempted. These results indicate that there is an interaction of water loss and fruit ripening in promoting abscission zone development in cluster tomatoes.
The Effect on Substrate Silica Incorporation on Post-germination Damping Off of Vinca
Authors: Evans Michael R. , Krumpelman Bernard W. , Sealy Ramsey , Rothrock Craig S.
Published: February 2019

Vinca (Catharanthus roseus) is a common annual bedding plant species that is susceptible to root and stem rot caused by Phytophthora nicotianae. The experimental design was a 6×2×1 factorial with a total of 12 treatment combinations that had five replications and was repeated twice. Vinca seeds were planted in the middle nine plugs of a 5×5 five-milliliter round plug tray filled with sphagnum peat (control) or peat amended with 2.1 kg/m3 calcitic lime, 5.9 and 7.3 kg/m3 potassium silicate alone and combined with 3.0 kg/m3 calcium sulfate. A peat control drenched with metalaxyl after inoculation was also included. After germination, when the seedlings had one true leaf, half of the treatments were inoculated with 500 cfu of Phytophthora nicotianae per plug cell while the other half remained uninoculated. The percentage of germination for the potassium silicate combined with calcium sulfate (KSCS) (79% and 78%) was similar to the control (86%) and the metalaxyl treatment (83%), whereas the potassium silicate alone had poorer germination (69% and 71%) and plant growth. The percentage of mortality for the KSCS treatment (6% and 14%) was similar to the metalaxyl treatment (9%) but was significantly less than the control (100%). The average dry shoot and root weights for the KSCS treatments (4.4 and 4.9 mg; 2.7 and 2.2 mg) were similar to the metalaxyl treatment (5.0 and 3.6 mg) and the uninoculated control (5.0 and 3.2 mg), but were higher than the potassium silicate treatment alone (2.1 and 1.6 mg; 0.7 and 0.6 mg).
N, P, and K Requirements of a Hybrid Nobile Dendrobium
Authors: Bichsel Rebecca G. , Starman Terri W. , Wang Yin-Tung
Published: February 2019

Three experiments were conducted to determine how nitrogen (N), phosphorus (P), and potassium (K) rate and nutrient termination date would affect the growth of Dendrobium nobile Red Emperor `Prince'. For each experiment, 150 one-year-old liner plugs, each with a single psuedobulb, were potted on 4 Feb. 2005. Each of the factorial experiments had five rates of the nutrient and three termination dates. The rates for N and K were 0, 50, 100, 200, and 400 mg·L-1. P rates were 0, 25, 50, 100, and 200 mg·L-1. Termination dates for all experiments were 1 Sept., 1 Oct., and 1 Nov. 2005. Ten months after planting when plants had ceased growing, data were collected for plant height, node number, number of leaves remaining, chlorophyll readings for the lower, middle, and upper leaves, and pseudobulb width and thickness. With one exception, interactions between fertilizer rate and termination date were nonsignificant for the variables measured. For all nutrients, terminating fertilization on 1 Oct. or 1 Nov. resulted in decreased pseudobulb thickness compared to 1 Sept. Prolonged fertilization with N resulted in slightly thinner pseudobulbs. Pseudobulbs grew taller as N rate increased, reaching its peak at 100 and 200 mg·L-1, and declined as N further increased to 400 mg·L-1. Plants had increasing chlorophyll readings in the middle leaves with increasing N rate. All P rates resulted in taller plants with equally more nodes compared to 0 mg·L-1. As K rate increased from 0 to 100 mg·L-1, height and node number increased, but there were no further increases in height at high rates. Number and percentage of leaves remaining increased as N and K rates increased.
Can Cover Crop-based Systems Reduce Vegetable Crop Fertilizer Nitrogen Requirements in the Southeastern United States?
Authors: Avila Laura , Scholberg Johannes , Zotarelli Lincoln , McSorely Robert
Published: February 2019

Poor water- and nutrient-holding capacity of sandy soils, combined with intense leaching rainfall events, may result in excessive N-fertilizers losses from vegetable production systems. Three cover cropping (CC) systems were used to assess supplemental N-fertilizer requirements for optimal yields of selected vegetable crops. Fertilizer N-rates were 0, 67, 133, 200, and 267; 0, 131, and 196; and 0, 84, 126,168, and 210 kg N/h for sweet corn (Zea mays var. rugosa), broccoli (Brassica oleracea), and watermelon (Citrullus lanatus), respectively. Crop rotations consisted of sunn hemp (Crotalaria juncea) in Fall 2003 followed by hairy vetch (Vicia villosa), and rye (Secale cereale) intercrop or a fallow. During Spring 2004, all plots were planted with sweet corn, followed by either cowpea (Vigna unguiculata) or pearl millet (Pennisetum glaucum), which preceded a winter broccoli crop. Hairy vetch and rye mix benefited from residual N from a previous SH crop. This cropping system provided a 5.4 Mg/ha yield increment for sweet corn receiving 67 kg N/ha compared to the conventional system. For the 133 N-rate, CC-based systems produced similar yields compared to conventional systems amended with 200 kg N/ha. Pearl millet accumulated 8.8 Mg/ha—but only 69 kg N/ha—and potential yields with this system were 16% lower compared to cowpea system. For a subsequent watermelon crop, trends were reversed, possibly due to a delay in mineralization for pearl millet. Because of its persistent growth after mowing, hairy vetch hampered initial growth and shading also delayed fruit development. Although CC may accumulate up to 131 kg N/ha actual N benefits, N-fertilizer benefits were only 67 kg N/ha, which may be related to a lack of synchronization between N release and actual crop demand.
Promotion of Flowering in Apple with NAA and Ethrel
Authors: McArtney Steven J. , Unrath Dick
Published: February 2019

Experiments were carried out in the southeastern United States between 1998 and 2006 to evaluate the potential for applications of NAA, Ethrel, or both, in the on-year of a biennial bearing cycle to increase return bloom in apple. Four bi-weekly applications of 5 ppm NAA beginning in mid June (summer NAA) increased return bloom, measured as the percentage of floral spurs in the year after treatment. The level of return bloom on trees receiving a summer NAA program was more than 2-fold higher than on untreated control trees, averaged across seven different experiments. Four applications of 5 ppm NAA at weekly intervals leading up to harvest (August/September) increased return bloom also. Combining 150 ppm Ethrel with summer NAA sprays resulted in an additive effect on return bloom compared to NAA or Ethrel alone. The effect of flower cluster density on return bloom the following year was more negative on control trees than it was on trees sprayed with Ethrel in the previous year. Treatment effects on fruit maturity at harvest were generally neutral, although flesh firmness was reduced in some experiments. NAA or Ethrel sprays in the on-year of a biennial bearing cycle may provide a strategy for achieving more consistent flowering and cropping in apple.
Influence of Indolebutyric Acid Potassium Salt on Propagation of Semi-hardwood Stem Cuttings of Bougainvillea
Authors: Cerveny Christopher B. , Gibson James L.
Published: February 2019

Bougainvillea glabra is a tropical species with reportedly difficulty to propagate. Previous research has shown the importance of talc-based rooting hormones when propagating Bougainvillea, yet little has been published on the efficacy of liquid-based formulations. Therefore, our objective was to determine the optimum concentration of indolebutyric acid potassium salt (KIBA) needed to effectively root semi-hardwood stem cuttings of Bougainvillea `California Gold' and `Helen Johnson'. Sub-terminal cuttings measuring 6.5 cm were harvested from stock plants of Bougainvillea on 3-week intervals from 6 June to 8 Aug. and repeated 6 Sept. to 8 Nov. 2005. Cuttings were dipped 0.5 cm in a solution of 0, 1500, 3000, or 6000 mg·L-1 KIBA or in a 1500-mg·L-1 solution containing indolebutyric acid (IBA) 1%: napthaleneacetic acid (NAA) 0.5% and propagated under mist. Cuttings were evaluated for percent survival, rooting quality (1 = poor; 5 = best), and number of primary and lateral roots 5 weeks after planting (WAP). Differences in `California Gold' for percent survival, average rank, and number of roots were determined not significant at P ≤ 0.05. However, application of rooting hormone to `Helen Johnson' increased rooting quality, number of primary roots, and number of lateral roots by up to 24%, 53%, and 50%, respectively. Results indicated rooting performance was generally improved with application of KIBA; therefore, cuttings of Bougainvillea may benefit from a 1500-mg·L-1 solution. KIBA was also found to be as effective as the industry standard liquid formulation. Growers will have to consider the availability and cost of KIBA when propagating Bougainvillea.
Response of Coleus (Solenostemon scutellarioides) to Plant Growth Regulators Applied during Propagation
Authors: Boldt Jennifer K. , Barrett James E.
Published: February 2019

A daminozide plus chlormequat chloride tank mix spray was applied to six Coleus cultivars or breeding lines at different times during propagation. For UF 03-8-10 and `Coco Loco', plants sprayed on day 7 or day 10 were shorter than control plants at transplant, but plants sprayed on day 13 were not. Other cultivars did not respond to single applications. Five of the six cultivars responded to application on days 7 and 13. Plants of UF 03-8-3 and `Coco Loco' were significantly shorter than control plants at transplant. Plants of UF 03-8-10, UF 03-6-1, and UF 03-17-8 were shorter than control plants at 3 weeks after transplant. `Hurricane Louise' did not respond to the tank mix. A second study found a cultivar specific response to three chemical treatments applied as a spray on day 10 of propagation. At transplant, UF 03-8-10, UF 03-8-3, UF 03-6-1, and `Coco Loco' plants sprayed with the tank mix at 2500 plus 1500 mg·L-1, respectively, were significantly shorter than the control plants. A uniconazole spray at 2 mg·L-1 reduced elongation in UF 03-8-10, UF 03-8-3, and UF 03-6-1, compared to control plants. Ethephon at 250 mg·L-1 reduced elongation in UF 03-8-10, UF 03-8-3, and `Coco Loco' plants. None of the chemical sprays reduced elongation in `Hurricane Louise' at the concentrations applied. Ethephon increased axillary branching in all cultivars, and induced lower leaf abscission in UF 03-17-8 and `Hurricane Louise'; leaf malformation in UF 03-6-1 and `Coco Loco'; and color alteration in UF 03-6-1, UF 03-8-3, and `Coco Loco'.
A Fresh Look at Avocado Pollination
Authors: Davenport Thomas L. , Ying Zhentu , Schnell Raymond J.
Published: February 2019

The synchronously dichogamous flowering behavior of avocado has historically been assumed to promote cross-pollination. Preliminary studies in southern California have revealed that self-pollination is more typical. The primary objective of the California research is to determine the paternity of individual fruit sampled during early and late fruit development using SSR markers. Cultivars included Hass as the primary cultivar and Bacon, Ettinger, Fuerte, Harvest, Lamb Hass, Marvel, Nobel, SirPrize, and Zutano serving as cross-pollinizing cultivars. We were able to: 1) estimate proportions of self- and cross-pollinated `Hass' fruit with cultivars planted in rows of varying proximity to the `Hass' rows; determine if the proportion of outcrossed fruit increased during maturity due to preferential abscission of self-pollinated fruit; and 2) determine if there is preferential retention of fruit cross-pollinated by a specific cultivar during maturation. On average, cross-pollination by any individual cultivar in 2004 was 6% or less in marble-sized fruit. Over 70% of the fruit were self-pollinated. This is greater than the proportion of self-pollination (about 30%) observed in near-mature fruit harvested in the previous year, 2003. Proportions of marble-sized fruit pollinated by each cultivar within each row were compared to the proportions of self or cross-pollinations in fruit harvested from the same trees at near-maturity. We observed about a 10% increase in proportion of self-pollinated fruit and a concomitant decrease in retained fruit derived from cross-pollination. Self-pollination appears to be the dominant mode of pollination. These preliminary results indicate that trees benefit from it, perhaps in preference over cross-pollination.
Crop Strategies Impact on Yield and Head Quality Components of Globe Artichoke in Southwest Texas
Authors: Leskovar Daniel , Goreta Smiljana , Yoo Kil Sun , Piccinni Giovanni , Agehara Shinsuke
Published: February 2019

Introduction of artichokes in the Wintergarden of Texas, an area with mild winters and hot summers, depends on the development of strategies that will overcome limiting climatic conditions for bolting, earliness, and length of harvest. Cultivars with different bolting requirements were evaluated at two planting times and irrigation rates. The cultivars Emerald, Experimental Red, Imperial Star, Green Globe, and Purple Romagnia were transplanted in the field on 27 Sept. and 3 Dec. 2004, and evaluated at 100% and 75% crop evapotranspiration rates (ETc) at Uvalde, Texas (29°1' N; 99°5' W). Harvests started on 24 Mar. and 21 Apr. 2005 for the first and second planting dates, respectively. Yield increased more than 3-fold for the first compared to the second planting date. Irrigation rates did not affect yield, water use efficiency, or head quality. The cultivars Emerald, Imperial Star, and Experimental Red were earlier than Green Globe and Purple Romagnia. The highest yield was measured for cv. Imperial Star, while the largest head weight was for cv. Green Globe. Total fibers, crude protein, and phenolic compounds concentration depended on cultivar, whereas the total sugar concentrations in the edible part of the head were similar among cultivars. Head weight, percentage of heart, and crude protein concentration decreased, whereas total fiber content increased as the harvesting season progressed. Integrating environmental and cultivar strategies aimed at earliness, large head size, and enhanced level of health-promoting compounds, will contribute to the potential production of globe artichokes in the region.
Root Development of Chile Peppers Under Two Different Irrigation Regimes
Authors: Silva Erin , Renz Mark , Walker Stephanie
Published: February 2019

Chile pepper (Capsicum annum) production in the southwest can be impacted by many factors. In particular, factors that alter root growth and development can be critical to pepper productivity. Several factors can cause less-than-optimal taproot formation, including irrigation practices, planting method (seeds vs. transplants), climactic conditions, and competition from weed species for limiting resources. The goals of this research were to quantify the root development of chile peppers established from either seeds or transplants under furrow and drip irrigation. Research was conducted in 2005 at Artesia Plant Science Research Center in Artesia, N.M., using a state-of-the-art drip irrigation system. Differences in root development between both irrigation types and planting methods were measured using of the mini-rhizotron image capturing system. Measurements occurred at a weekly basis to document location, root length density, and pattern of root formation. At the time of harvest, yield and fruit quality were evaluated. Direct-seeded chile plants yielded more fruits than transplanted chile under both irrigation regimes. Patterns of root development differed over time for direct-seeded vs. transplanted and furrow vs. drip-irrigated chile peppers. Planting and irrigation method affected root growth differently at various points in the season. These data can aid in the optimization of management strategies for specific production practices.
Organic Garlic Research in Colorado; Winter Mulching, Irrigation Systems, Spacing, Scape Removal, and Flame Cultivation
Authors: Guenther Debra , Stonaker Frank
Published: February 2019

The Specialty Crops Program at Colorado State University conducted research of hardneck garlic (Allium sativum ophioscorodon) production on certified organic land at the Horticulture Field Research Center northeast of Fort Collins, Colo., during the garlic growing seasons of 2002–03 and 2003–04. Winter mulches and irrigation treatments were studied during the first season. It was found that garlic that was covered by any type of winter mulch (grass hay, single or double layers of floating row cover) resulted in better yields (higher average bulb weight) than garlic which was not covered at all (ANOVA, F = 2.93, P = 0.034). Yields from sprinkler and furrow irrigation were essentially the same; however, furrow irrigation used nearly 30% more water. Too little water was applied to the drip-irrigated treatment and yield suffered. Our findings suggest that yields are negatively impacted when less than 12 inches of combined precipitation and irrigation are received. During the second season, clove planting spacings of 3, 4.5, and 6 inches, and flame weeding and scape removal effects on yields were studied. The bulbs that grew at a 6-inch spacing were significantly larger than those grown at 3 and 4.5 inches (ANOVA, F = 46.5, P < 0.001). Flame weeding had no significant effects on yields (t-test, P = 0.6) and may be more economical compared to hand weeding depending on fuel costs. Removing the scapes did result in slightly higher bulb weights (t-test, P = 0.06). Removing scapes takes extra labor and may not be worth the time for only slightly higher bulb weights; however, selling the edible scapes may offset the cost and generate extra income.
Reducing Phosphorus Use for Sweet Corn Grown on Calcareous Gravelly Soils
Authors: Olczyk Teresa , Li Yuncong , Wang Xing , Simonne Eric
Published: February 2019

Sweet corn (Zea mays) is a major cash crop produced on calcareous soils in Miami–Dade County. Applications of large amounts of phosphorus (P) fertilizer for many years resulted in the accumulation of high levels of P in these soils. Accumulated P is slowly released into the soil solution to become available for plant roots. Previous studies conducted in this area showed little or no yield and crop quality response to P fertilizer applications. Large-scale field trials with reduced P applications were conducted in a grower's field. The treatments were: 1) no P; 2) 50% grower's rate; and 3) 100% grower's rate with six repilications. The data collected included: plant stand, height, nutrient concentrations in leaf tissue, leaf chlorophyll, tip fill, number, and weight of marketable ears/acre. Reduced rates of P fertilizer did not significantly reduce yield and quality of sweet corn.
Nitrate Leaching, Yields, and Water-use Efficiency of Zucchini Squash (Cucubita pepo) under Different Irrigation and Nitrogen Rates and Methods in a Sandy Soil
Authors: Zotarelli Lincoln , Scholberg Johannes , Dukes Michael , Snyder Hannah , Simonne Eric , Munoz-Carpena Michael
Published: February 2019

On sandy soils, potential N contamination of groundwater resources associated with intensively managed vegetables may hamper the sustainability of these systems. The objective of this study was to evaluate the interaction between irrigation system design/scheduling and N fertilization rates on zucchini production and potential N leaching. Zucchini was planted during Fall 2005 using three N fertilizer rates (73, 145, 217 kg/ha) and four different irrigation approaches. Irrigation scheduling included surface-applied drip irrigation and fertigation: SUR1 (141 mm applied) and SUR2 (266 mm) using irrigation control system (QIC) that allowed time-based irrigation (up to five events per day) and a threshold setting of 13% and 15% volumetric water content (VWC), respectively; Subsurface drip irrigation (SDI) using a QIC setting of 10% VWC (116 mm) combined with surface applied fertigation; and a control treatment with irrigation applied once daily (424 mm). Leacheate volumes were measured by drainage lysimeters. Nitrate leaching increased with irrigation rate and N rate and measured values ranged from 4 to 42 kg N/ha. Use of SDI greatly reduced nitrate leaching compared to other treatments. SDI and SUR1 treatments had no effect on yields (29 Mg/ha). However, SDI had a 15% and 479% higher water use efficiency (WUE) compared to SUR1 and the fixed irrigation duration treatment. Application of N in excess of intermediate N-rate (standard recommendation) did not increase yield but yield was reduced at the lowest N-rate. It is concluded that combining sensor-based SDI with surface applied fertigation resulted similar or higher yields while it reduced both water use and potential N leaching because of improved nutrient retention in the active root zone.
Physiological Changes in Cantaloupe during Development and in Stored Fresh-cuts Prepared from Fruit Harvested at Various Maturities
Authors: Beaulieu John , Lea Jeanne
Published: February 2019

Cantaloupe (Cucumis melo Var. reticulatus, Naudin) were evaluated during development and then fresh-cuts were stored after preparation from various maturities to track quality changes during storage. Flowers were anthesis tagged one morning and developing fruit were harvested weekly at 13, 20, 27–28, and 34–35 days after anthesis (DAA). Mature fruit were harvested at 37–38 DAA with five distinct maturities: 1/4-, 1/2-, 3/4-slip, full-slip and over-ripe. Hunter L* and a* color values indicated change from pale green to light orange that occurred after 28 DAA. There were significant decreases in L*, a* and b* by day 9 in storage as fresh-cuts. After 28 DAA, sucrose dramatically increased, and this was positively correlated with increases in both total sugars (r = 0.882, P = 0.084) and °Brix (r = 0.939, P = 0.041). Gradual subjective deterioration occurred during storage, which was independent of maturity. There was a negative linear trend over the length of storage in hand-held firmness for each maturity level and the slopes decreased significantly with increasing maturity; indicating the effect of storage duration decreased as maturity increased. Vitamin C had a significant increasing trend (P-value = 0.042) during development from 12 through 35 DAA, then losses were greater in fresh-cuts prepared from full-slip fruit (65%) than in less mature fruits, quarter-slip 40%, half-slip 48%, and three quarter-slip 50%. The pH of mesocarp tissue dropped to the lowest value (5.25) just prior to physiological maturity, then peaked after harvest (6.51–6.79), and generally declined by the end of freshcut storage. In sum, considering other publications on this study, and herein, fruit should be harvested at greater than or equal to 1/2-slip to attain optimum quality and storability.
Short Days or Vernalization Promote Flowering in Aquilegia ×hybrida Sims `Origami Blue and White'
Authors: Whitman Catherine M. , Runkle Erik S. , Cameron Arthur C.
Published: February 2019

Flowering of Aquilegia is generally considered to require vernalization, while photoperiod has little or no effect. The cold treatment is most effective when plants have passed the juvenile stage (often 12 to 15 leaves) prior to vernalization. We performed experiments on a cultivar reported to have a reduced vernalization requirement. Seedlings of Aquilegia ×hybrida Sims `Origami Blue and White' in 128-cell plug trays with four or five leaves were either placed directly into a 5 °C cooler or transplanted to 13-cm containers. Plants were grown (bulked) for 0, 3, or 6 weeks at 20 °C under 9-h short days (SD) or 16-h long days (LD) provided by incandescent lamps at 1 to 3 μmol·m-2·s-1. Plants had seven or eight leaves after 3 weeks bulking and 13 or 14 leaves after 6 weeks bulking. They were then cooled at 5 °C for 0, 5, or 10 weeks and placed in a common forcing environment of 20 °C under an LD provided by high-pressure sodium lamps. Aquilegia plants placed directly into the forcing environment flowered in 89 and 97 days in years 1 and 2, respectively. Flowering percentage of plants cooled in the plug tray decreased with increasing duration of cold treatment, and only 15% flowered after a 10-week cold treatment. All plants bulked for 3 or 6 weeks prior to cold treatment flowered, and in 26 to 35 days. Surprisingly, all plants that were moved directly from bulking treatments to the forcing environment (no cold treatment) flowered, and flowering was most rapid (36 days) in plants exposed to 6 weeks of SD before forcing. Therefore, our data indicate that SD can at least partially substitute for a cold treatment in this Aquilegia cultivar.
Floating System Production of Liatris spicata (L.) Willd.
Authors: Zanin Giampaolo , Sambo Paolo
Published: February 2019

Liatris is an ornamental plant cultivated as a garden perennial for more than 70 years. Since the early 1970s, Liatris spicata has gained importance as a cut flower because of its long-lasting flowering and its peculiar downward flowering succession. This species is usually cultivated in beds both outdoors and in greenhouses. However, in order to improve yield and quality production, some research has been carried out on soilless cultivation. In particular, floating systems seem to provide the best performances, although only different nutrient solutions or their concentrations have been studied. In this research, in addition to two different concentrations of Hoagland solution [full-strength (H) and a half-strength (1/2H)], three corm circumferences (8/10, 10/12, and 12+) and three plant densities (36, 48, and 60 plants/m2) were also evaluated. The full-strength solution gave the best performance from both qualitative and quantitative standpoints. This nutrient solution also showed, at the end of the experiment, very high residual nitrate-N, which could induce environmental pollution during disposal. Furthermore, the management of the solution appeared more difficult and time-consuming. All these aspects should be taken into account by growers in making choices. Corm size also affected production. Increasing circumference from 8/10 to 12+ increased marketable stems per plant and their quality traits, but, because of the highest mortality of plants observed with the bigger corms, yield per square meter did not increase over corm size of 10/12. Finally, rising plant density from 36–60 plants/m2, the biomass of the single plant decreased. However, it resulted also in the enhancement of sellable production per square meter.
Construction of a cDNA Library of Vitis pseudoreticulata Native to China Inoculated with Uncinula necator and the Analysis of Potential Defense-related Expressed Sequence Tags
Authors: Xu Yan , Wang Yuejin
Published: February 2019

Expressed sequence tags (ESTs) constitute a rapid and informative strategy for studying gene-expression profiles of specific stages of annual and perennial plant species. Compared with annual plants, the NCBI database has very little sequence information from perennial plant species. To date, only ∼145 ESTs of Vitis pseudoreticulata W.T. Wang have been deposited in databases. This is insufficient to understand the biology and development of this species. In this report, a cDNA library constructed from young leaf inoculated with powdery mildew pathogen [Uncinula necator (Schw.) Burr.] of Chinese wild Vitis pseudoreticulata. Leaf was harvested at various times after inoculation for total RNA extraction, which was used to generate ESTs. In our study, 107 cDNA clones were sequenced either from 5' or 3' end of the cDNAs. Among them, 60 unigenes (56%) were functionally characterized by the BLASTX matches to known function proteins, and 20 unigenes (18.6 %) matched significantly with those having unknown function in the public databases. The remaining 27 unigenes (25.2%) failed to show significant homology to any proteins in the public databases, suggesting that they represent novel sequences. Some functional genes identified from the cDNA library to be potentially associated with plant defence-related responses are discussed.
Predicted Crop Value for a Cling Peach and Three Nectarines of Different Harvest Seasons as a Function of Crop Load
Authors: Reginato Gabino , Robinson Terence , de Cortazar Victor Garcia
Published: February 2019

Several field experiments to assess the effect of tree size and crop load on fruit size and yield were conducted in a `Ross' cling peach orchard and in three nectarine orchards of different harvest seasons in Chile. Trees were randomly selected in each orchard and then hand-thinned at the beginning of pit hardening to a wide range of crop loads. The fraction of above-canopy photosynthetically active radiation intercepted by the canopy (PARi) was determined at harvest and all fruits were counted, weighted, and average fruit weight calculated. Cropload and yield were expressed in terms of fraction of PARi. Data on farm gate prices for export fruit of different sizes and export dates were obtained from a Chilean export company. For each orchard, the relationship between cropload and fruit size or cropload and yield efficiency was assessed by regression analysis. Fruit size distribution was calculated from adjusted fruit size assuming a normal fruit size distribution and valued according to shipment date and price. Using crop load as a covariate, fruit size adjusted for cropload was calculated for each nectarine orchard. Differences in adjusted fruit size and yield efficiency were detected among cultivars. Predicted crop value, normalized in terms of PARi intercepted, was calculated for all the cultivars. Large differences in predicted crop value were found for early, mid-season, and late-ripening nectarines. The early and late ripening cultivars showed the highest predicted crop value, especially at lower crop loads and larger fruit sizes. On the other hand, `Ross' cling peach showed its highest crop value at a medium crop load with high yield and relatively small fruit size. (Funded by FONDECYT grant 1930695.)
Automatic Detection of Fine Roots in Minirhizotron Images
Authors: Zeng Guang , Birchfield Stanley , Wells Christina , Layne Desmond
Published: February 2019

Minirhizotrons and specialized camera equipment have been widely adopted for in situ observation of fine root dynamics in horticultural settings. However, the laborious nature of data collection from minirhizotron images limits the number and size of experiments that can reasonably be analyzed. Here we present an algorithm for the automatic detection and measurement of roots in minirhizotron images, including the discrimination of light-colored roots from bright background objects. First, two-dimensional matched filtering and local entropy thresholding are used to produce binarized images from which roots are detected. Next, a strong root classifier based on geometric and intensity features is used to discriminate roots from unwanted background objects. A labeling algorithm identifies each individual root in the image, and root lengths and diameters are measured using Dijkstra's algorithm and the Kimura–Kikuchi–Yamasaki method for obtaining the length of a digitized path. This approach allows us to identify and measure fine roots as individuals, rather than simply measuring the aggregate root length in an image. Experimental results from a collection of 250 peach (Prunus persica) root images demonstrate the effectiveness of the approach. The algorithm is able to detect and measure a variety of roots of different shapes, sizes, and orientations, with a detection rate of 92%, a false–positive rate of 5%, and an average measurement error of 4.1% and 6.8% for length and diameter, respectively. Current work involves improving the efficiency of the algorithm and incorporating it into an application. We are also exploring algorithms for tracking the location of a root over time as it grows darker in color and blends with the surrounding soil.
Liquid Effluent from Poultry Waste Bioremediation as a Nutrient Source for Hydroponic Cucumber Production
Authors: Liedl Barbara E. , Wilfong Kristen , Taylor Christina , Mazzaferro Kari
Published: February 2019

Fertilizer costs and increased awareness of point-source pollution are amplifying the pressures on farming, economics along with public demand for sustainable production methods and organically grown produce. Our research focuses on using effluent from thermophilic anaerobic digestion of poultry litter as an alternative fertilizer. Cucumbers (Cucumis sativus L.) were grown hydroponically using a bato bucket system to evaluate the effects of liquid effluent as a nutrient solution versus a commercial nutrient solution. Seeds of the beit alpha cultivar `Manar' were started in Horticubes and transplanted into buckets containing a perlite/coir media. The effluent fertilizer consisted of effluent diluted to the same ppm nitrogen found in the commercial fertilizer based on ammonium measured in the effluent. Hydroponic solutions were monitored twice a day to maintain a pH of 5.6-6.0. Fruit was harvested three times a week and graded on size and shape. Fruit of each grade were counted, weighed, and recorded. Average fruit weight and fruit number produced was statistically significant between the two fertilizer regimes with the commercial fruit, averaging 84 g compared to 75 g for effluent fruit. The effluent treatment produced a greater percentage of grade 1 fruit (33%) compared to the commercial treatment (26% grade 1 fruit). Thus, 74% of the commercial harvest was grade 2 or cull fruit compared to only 66% of the effluent harvest. Correlating grade with average fruit weight analysis identified statistical differences between treatments for the grade 1 fruit, but not the grade 2 or the culls. While effluent from thermophilic anaerobic digestion shows promise as an alternative hydroponic fertilizer, it is not better than the commercial fertilizer regime.
NaCl Stress in Hydroponic Tomatoes Can Be Alleviated by Calcium
Authors: Montesano Francesco , van Iersel Marc W.
Published: February 2019

The availability of good quality irrigation water is decreasing worldwide, and salinity is an increasingly important agricultural problem. To determine whether detrimental effects of NaCl can be minimized by additional Ca2+, tomato (Lycopersicon esculentum Mill.) `Super-sweet 100' was grown hydroponically. The basic nutrient solution contained 11.9 mM NO -3 and 3.2 mM Ca 2+. We added 14.1, 44.4 and 70.4 mM of NaCl to this solution to determine the effect of NaCl and there were treatments with 70 mM NaCl and 10 or 20 mM Ca2+ to look at Ca2+ effects. We also included three treatments in which all nutrient concentrations were increased (without NaCl) to distinguish between osmotic and ion-specific effects. 70.4 mM NaCl reduced leaf photosynthesis, chlorophyll content, gas phase conductance for CO2 diffusion, carboxylation efficiency, and dark-adapted quantum yield of photosystem II. The inclusion of 20 mM Ca2+ prevented these effects of NaCl. NaCl also decreased leaf size and elongation rate, but this could not be prevented by adding extra Ca2+ to the nutrient solution; these were caused by osmotic effects, rather than Na+ specifically. Likewise, plant dry mass was negatively correlated with solution EC, suggesting an osmotic effect. Our results indicate that leaf area development, which was inhibited by high EC, is more important for dry matter accumulation than leaf photosynthesis, which was inhibited by high Na+. Adding 20 mM Ca2+ to the 70 mM NaCl solution reduced the Na+ concentration in the leaf from 79 to 24 mg·g-1, which may explain why Ca2+ alleviates Na+ toxicity.
Water Stress and Growth of Native and Introduced Shrub Species as Influenced by Irrigation Regime
Authors: Scheiber Sloane M. , Beeson Richard C. , Bass Heather
Published: February 2019

Native plants are often promoted as an approach for water conservation in urban landscapes. However, information regarding plant water needs is based primarily upon anecdotal observations of plant performance. Direct comparisons between native and introduced species using physiological measures of plant water stress are unavailable to support or refute such recommendations. Ligustrum japonicum and Myrica cerifera, representing an introduced and native species, respectively, were transplanted into a fine sand soil to evaluate establishment rates and growth characteristics under two irrigation regimes. Each species was irrigated either daily or every 3 days and received 1.3 cm of irrigation per event for 8 months after transplant. Predawn, midday, and dusk water potentials were recorded on three consecutive days monthly, with cumulative stress intervals calculated. Height, growth indices, shoot dry mass, root dry mass and leaf area were also recorded. Water potential was significantly influenced by day of water stress level. On days without irrigation, water stress was generally greater and affected growth. Myrica irrigated daily had the greatest growth, yet plants receiving irrigation every 3 days had the least growth and greater leaf drop. In contrast, for Ligustrum there were no differences between irrigation regimes in growth responses except for growth index.
`SuperMac' Apple
Authors: Khanizadeh Shahrokh , Groleau Yvon , Levasseur Audrey , Carisse Odile , Rekika Djamila , DeEll Jennifer , Privé Jean-Pierre , Alli Inteaz , Kemp Henk
Published: February 2019

`SuperMac' (Malus ×domestica Borkh) is being released as a replacement for `Spartan', which is presently being grown in Eastern Canada for its excellent shelf life. However, it is susceptibility to scab [Venturia inaequalis (Cke) Wint.], the most common apple disease. This new cultivar produces larger fruit than `Spartan' and is resistant to apple scab. It is very attractive (Fig. 1), has a pleasant taste and an excellent shelf life, and keeps very well and longer compared with the `Spartan'. `SuperMac' is a `McIntosh'-type apple. The tree is hardy to –30 °C, and the fruit and leaves are resistant to the common races of apple scab resulting from the presence of the Vf gene derived from Malus floribunda 821.
Cloning and Characterization of Glycolate Oxidase and NADH-Dependent Hydropyruvate Reductase Genes in Pachysandra terminalis
Authors: Zhou Suping , Chen Fur-Chi , Nahashon Samuel , Chen Tingting
Published: February 2019

Photorespiration provides a protection mechanism in plants by diverting excessive energy accumulated from photochemical reaction, metabolizing toxic products and producing some protective molecules. The authors report cloning and characterization of a glycolate oxidase gene (GOX; NCBI accession DQ442286) and a NADH-dependent hydroxypyruvate reductase gene (HPR; NCBI DQ442287) from Pachysandra terminallis. The DQ442286 had the predicted GOX-like–Riboflavin-5′-phosphate (FMN) conserved domain and the DQ442287 had the predicted adenosine 5′-(alpha-thio)diphospho-5′-ribofuranosylnicotinamide nicotinamide adenine dinucleotide (NAD) binding domain (2-Hacid_DH_C). C-terminal peroxisome targeting signal was predicted to be -ARL for DQ442286 and –SKL for DQ442287. Both genes encoded enzyme proteins that are located in peroxisome and are involved in the photorespiration process. Real-time quantitative reverse-transcriptase polymerase chain reaction was performed to compare transcript level of the cloned genes after cold treatment. The 18s Ribosomal RNA (rRNA) was included to calibrate the data. The relative cycle threshold values (gene/18s rRNA) were 1.4, 1.5, and 1.5 for GOX and 1.2, 1.3, and 1.3 for HPR in the treatments of 4 °C 4 h, 4 °C 12 h, and control. The data revealed that gene expression was enhanced by only short-term (4-h) cold treatment. A ribulose-1, 5-biphosphate carboxylase/oxygenase (Rubisco) activase gene (DQ 486905) was also cloned and analyzed following the same procedure.
Evaluation of Growth Regulator Inhibitors for Controlling Postbloom Fruit Drop (PFD) of Citrus Induced by the Fungus Colletotrichum acutatum
Authors: Chen Hui-Qin , Dekkers Katherine L. , Cao Lihua , Burns Jacqueline K. , Timmer L. W. , Chung Kuang-Ren
Published: February 2019

Postbloom fruit drop (PFD) of citrus is incited by the fungus Colletotrichum acutatum J. H. Simmonds and may result in young fruit drop and severe yield losses. Previous studies suggested that imbalance of growth regulators such as auxin, ethylene, and jasmonic acid (JA) plays an essential role in young fruit abscission. In this work, we determined the factors associated with fungal-induced fruit drop by testing compounds inhibitory to hormonal transport or biosynthesis. As assessed on sweet orange (Citrus sinensis Osbeck) and grapefruit (C. paradisi Macf.) for 4 years, we found that many auxin transport and action inhibitors such as 2,3,5-triiodobenzolic acid (TIBA), 2-(4-chlorophenoxy)-2-methyl-propionic acid (clofibrate), or quercetin and JA biosynthesis inhibitors such as salicylic acid (SA) and aspirin (methyl-SA) applied 7 d after C. acutatum infection resulted in higher percentages of young fruit retention compared with the water controls. The commercial products ReZist and Actigard, widely used as systemic acquired resistance (SAR) agents, also improved fruit retention. Furthermore, application of gibberellic acid (GA3) on sweet orange, regardless of C. acutatum infection, significantly increased fruit retention. These commercial products may be very useful in managing this destructive disease of citrus in the field.
Foliar Chlorosis in Field-Grown Red Maples
Authors: Altland James
Published: February 2019

Franksred red maple (Acer rubrum `Franksred') trees were sampled from nursery fields in 2003 and 2004 to determine the cause of a common foliar chlorosis. Plots in 21 and 39 different nurseries were identified in 2003 and 2004, respectively. A single plot from each nursery was sampled in June of each year, whereas two to four plots per nursery were sampled in September. Each plot consisted of 20 consecutive trees in a single row. From each plot, a foliar tissue sample was analyzed for the complete range of essential nutrients. Plant height, stem diameter, leaf chlorophyll content, and a subjective plant quality rating were also recorded. From each plot, a soil sample was collected and analyzed for pH, EC, organic matter, and a range of essential nutrients. The foliar chlorosis was determined to be incited by manganese (Mn) deficiency. Tissue Mn was highly correlated with soil pH. Chlorotic plants were smaller with less stem diameter than nonchlorotic plants. Sufficiency ranges for tissue and soil tests were determined and are provided for red maple nursery production.
`Sterling' Dieffenbachia
Authors: Henny R. J. , Chen J. , Norman D.J.
Published: February 2019

Species and cultivars of Dieffenbachia Schott. (Araceae Juss.) have been important ornamental foliage plants for many decades. Their attractive foliar variegation, adaptability to interior environments, and ease of production are major reasons for their importance as ornamental foliage plants. Approximately 20 cultivars are commercially produced in Florida. Previously, most new cultivars were clones introduced from the wild or chance mutations of existing cultivars. Currently, cultivars are introduced into production from plant breeding programs (Henny 1995a, b; Henny and Chen, 2003; Henny et al., 1987). The hybrid Dieffenbachia `Sterling' was developed by the tropical foliage plant breeding program at the Mid-Florida Research and Education Center.