bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Diversity in Muscadine and American Bunch Grapes Based on Randomly Amplified Polymorphic DNA (RAPD) Analysis
Authors: Qu Xianping , Lu Jiang , Lamikanra Olusola
Published: January 2019

Two morphologically distinct types of grapes belonging to the subgenera Euvitis and Muscadinia in the genus Vitis are cultivated in the United States. The former is commonly called bunch grapes while the latter is usually called muscadine. Genetic diversity among these grapes was investigated using RAPD markers. Sixteen grape cultivars, with parentage including V. rotundifolia Michx., V. vinifera L., and several American Vitis species, were used for the RAPD analysis. A total of 156 RAPD markers was produced from 19 random primers, over 90% of which was polymorphic among the muscadine and the bunch grapes. Polymorphisms were lower within each subgenus. Relationships between these two subgenera were estimated based on band-sharing and cluster analysis. The average genetic distance between the bunch and the muscadine grape cultivars was 0.45. The results based on DNA analysis agree with isozyme data obtained from a separate study, which demonstrated that muscadine grapes share very few common alleles with American bunch grapes and European grapes.
A Codominant Randomly Amplified Polymorphic DNA (RAPD) Marker Useful for Indirect Selection of Bean Golden Mosaic Virus Resistance in Common Bean
Authors: Urrea Carlos A. , Miklas Phillip N. , Beaver James S. , Riley Ronald H.
Published: January 2019

Bean golden mosaic virus (BGMV) is a devastating disease of common bean (Phaseolus vulgaris L.) in tropical America. The disease is effectively controlled by combinations of genetic resistances. The most widely deployed source of resistance to BGMV is a recessive gene (bgm-1) derived from the dry bean landrace cultivar Garrapato (Mexico) that conditions a nonmosaic partial resistance response to the pathogen. To expedite introgression of partial resistance into snap bean for southern Florida and other susceptible dry bean market classes for the Caribbean and Central American regions, a RAPD marker tightly linked to bgm-1 has been identified. Two contrasting DNA bulks, one consisting of five BGMV-resistant and the other five susceptible F6 recombinant inbred lines, were used to screen for polymorphic fragments amplified by 300 decamer primers in the polymerase chain reaction. RAPDs generated between the bulks were analyzed across F2 populations segregating for the marker and the gene. One codominant RAPD marker (R2570/530) tightly linked to the recessive resistance gene bgm-1 was found. The 530-base pair (bp) fragment was linked in repulsion with bgm-1 and the other 570-bp fragment was linked in coupling. No recombinants between R2570/530 and bgm-1 were observed among 91 F2 progeny from one dry bean population, and there were two recombinants (4.2 cM) observed among 48 F2 progeny combined across four snap bean populations. Assays of R2570/530 across susceptible germplasm and lines likely to have the `Garrapato'-derived partial resistance to BGMV have revealed that the codominant marker is gene-pool nonspecific and maintains its original linkage orientation with the recessive bgm-1 gene through numerous meioses. The codominant marker is useful for rapidly introgressing partial resistance to BGMV into susceptible germplasm.
Effect of pH and 1H-indole-3-butyric acid (IBA) on Rooting of Apple Microcuttings
Authors: Harbage James F. , Stimart Dennis P.
Published: January 2019

Involvement of pH and IBA on adventitious root initiation was investigated with Malus domestica Borkh. microcuttings. The pH of unbuffered root initiation medium (RIM) increased from 5.6 to 7 within 2 days. Buffering with 2[N-morpholino] ethanesulfonic acid (MES) adjusted to specific pHs with potassium hydroxide prevented pH changes and resulted in a 2-fold higher root count at pH 5.5 compared to pH 7 or unbuffered medium. As pH decreased, lower concentrations of IBA were required to increase root counts. Colorimetric measurement of IBA in buffered RIM showed greater IBA loss and higher root count were associated with lower pH levels in all cultivars. This suggests that IBA loss from RIM depends on medium pH, which affects root count. Root count differences between easy-to-root through difficult-to-root cultivars were not consistent with amount of IBA loss from RIM. Cultivar differences in root count could not be explained solely by IBA loss from RIM.
Responses of Two Somaclonal Variants of Quince (Cydonia oblonga) to Iron Deficiency in the Greenhouse and Field
Authors: Bunnag Sumonthip , Dolcet-Sanjuan Ramon , Mok David W.S. , Mok Machteld C.
Published: January 2019

Somaclonal quince (Cydonia oblonga Mill.) variants IE-1 and IE-2 (Dolcet-Sanjuan et al., 1992) were more tolerant to Fe-deficient conditions in vitro than the original clone Quince A. The tolerance was evidenced by higher chlorophyll concentrations in leaves, higher Fe(III) reduction in roots, and increased acidification of the medium. In Summers 1993 and 1994, the two variants and Quince A were compared in the greenhouse, grown in normal potting soil (pH 5) and in soil obtained from an Fe-deficient orchard, with and without the addition of lime and KHCO3 solution to increase the pH (up to pH 8.3) and intensify Fe stress. In both years, the variants had significantly higher leaf chlorophyll concentrations than Quince A when grown in high-pH soils. The Fe+2 concentrations in leaves were also higher in the variants. Under field conditions at IRTA Reus, Spain, IE-1 and IE-2 had higher chlorophyll concentrations than the controls at some, but not all, analysis dates. These results suggest that IE-1 and IE-2, when grown as young plants in the greenhouse, have higher tolerance to Fe deficiency than Quince A, as observed in vitro, but that the tolerance is more variable under uncontrolled conditions in the field.
Modeling the Peach Sugar Contents in Relation to Fruit Growth
Authors: Génard Michel , Souty Michel
Published: January 2019

The edible quality of peaches (Prunus persica L. Batsch) to a great extent depends on their sweetness, which is related to sugar composition. Our objective was to develop a model to predict carbon partitioning within fruit flesh and to predict the sucrose, sorbitol, glucose, and fructose contents. The model is dynamic and deterministic and was designed to be driven by the flesh dry-weight growth curve, flesh water content, and temperature data. It uses differential equations where the state of the system is defined by variables that describe how much carbon is present as each form of sugar and as other compounds (acids and structural carbohydrates). The rates of change of these amounts of carbon depend on the current values of corresponding variables and on the transfer functions between them. These functions are defined by rate constants or by functions of degree-days after full bloom. The model was calibrated and tested using data sets from treatments that covered several leaf: fruit ratios. The predictions of the model were in fairly good agreement with experimental data. A sensitivity analysis was performed to identify the most influential transfer function parameters. Carbon flows between sugar forms were analyzed. Sucrose, which was the most abundant sugar, and fructose, which is the sweetest, contributed most to fruit sweetness. Simulations were performed to study the effects of changes in fruit growth-curve parameters on sugar contents and concentrations.
Index of Injury Compared to Tissue Ionic Conductance for Calculating Freeze Damage of Cabbage Tissues
Authors: Manley Reeser C. , Hummel Rita L.
Published: January 2019

The index of injury (It) and tissue ionic conductance (gTi) formulas for analyzing electrolyte leakage data from freeze-stressed tissues of cabbage (Brassica oleracea L. Capitata group) were compared. The two formulas produced similar results in calculating the relative freezing responses of stem pith, lamina, and petiole tissues. Disagreement occurred only with lamina tissues when the magnitude of ion leakage was low. Vital staining of pith and petiole tissues with triphenyl tetrazolium chloride indicated that the tissue TK50 (the temperature resulting in 50% injury), derived from It data, was a reliable indicator of the freeze-killing point. These results support the use of the simpler It method for analyzing electrolyte leakage data in studies of cabbage freezing tolerance.
Light Intensity and Spectral Quality Affect Fruit Growth and Shelf Life of Greenhouse-grown Long English Cucumber
Authors: Lin W.C. , Jolliffe P.A.
Published: January 2019

The importance of light intensity and spectral quality on fruit color and shelf life of long English cucumber (Cucumis sativus L.) was studied in four greenhouse experiments. The intensity of cucumber greenness was measured nondestructively by video imaging, and shelf life was measured by visual observation of incipient yellowing. In the summer, filters were used to cover individual fruit to reduce light intensity reaching the fruit surface. The lower the light intensity incident on a cucumber, the shorter its shelf life. The average shelf life was 8, 5, or 1 days for cucumbers receiving 100%, 66%, or 31% of natural daylight, respectively. The fruit that were covered with a filter transmitting red (R) light were greener (low grey level via video imaging) than those with a far-red (FR) filter. In the fall, fruit receiving spectral R lighting from fluorescence tubes were greener and had a longer shelf life than those receiving FR lighting from incandescent bulbs. In the winter, high-pressure sodium (HPS) lighting was necessary to supplement natural daylight for crop growth and production. Under HPS, R and FR lighting produced the same fruit greenness and shelf life. In the spring, R-lighted fruit had longer shelf life than FR-lighted ones, although fruit color at harvest was similar. In these four experiments, postharvest shelf life of long English cucumber was generally related to fruit greenness upon harvest. The data suggest the importance of an open canopy in improving fruit greenness and shelf life of greenhouse-grown cucumbers.
Effects of Low-oxygen Atmosphere on Ethanolic Fermentation in Fresh-cut Carrots
Authors: Kato-Noguchi Hisashi , Watada Alley E.
Published: January 2019

Carrot (Daucus carota L.) root shreds were stored under a continuous flow of 0.5% and 2% O2 (balance N2) or in air for 7 days at 5 and 15 °C to study the regulation of ethanolic fermentation metabolism. Low-O2 atmospheres of 0.5% and 2% caused increases in ethanol and acetaldehyde concentrations and the activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) compared to air. By day 3, ethanol increased 38-, 25-, 13-, and 9.5-fold; acetaldehyde increased 20-, 13-, 7.7-, and 5.6-fold; ADH increased 7.6-, 6.3-, 3.8-, and 2.7-fold; and PDC increased 4.2-, 3.9-, 2.3-, and 2.2-fold in samples at 0.5% O2 at 15 or 5 °C and at 2% O2 at 15 or 5 °C, respectively, compared with corresponding samples in air. These results indicate that ethanolic fermentation was accelerated more in the 0.5% than in the 2% O2 atmosphere and more at 15 °C than at 5 °C. The acceleration of ethanolic fermentation may allow production of some ATP, which may permit the carrot tissues to survive.
Respiratory Changes Associated with Growth-regulator-delayed Leaf Yellowing in Easter Lily
Authors: Franco Rosanne E. , Han Susan S.
Published: January 2019

Senescence of excised Easter lily leaves is typically marked by a rise in respiration without a concomitant production of ethylene. Treating excised leaves with 500 mg·L-1 of gibberellic acid (GA3) or benzyladenine (BA) significantly delayed the onset of leaf yellowing, lowered the respiration rates by one-third to one-half, and markedly delayed the respiratory rise. Similar effects on respiration were detected in leaves treated with BA or GA3 before a 4-week period of cold storage and in leaves treated after chlorosis had initiated. Results of this study indicate that excised Easter lily leaves respond to the growth regulators with a significant decrease in respiration rate.
Water Relations and Drought Tolerance of Four Turfgrasses
Authors: Qian Yaling , Fry Jack D.
Published: January 2019

Greenhouse studies were conducted on three warm-season turfgrasses, `Midlawn' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy], `Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and `Meyer' zoysiagrass (Zoysia japonica Steud.), and a cool-season turfgrass, `Mustang' tall fescue (Festuca arundinacea Schreb.) to determine 1) water relations and drought tolerance characteristics by subjecting container-grown grasses to drought and 2) potential relationships between osmotic adjustment (OA) and turf recovery after severe drought. Tall fescue was clipped at 6.3 cm once weekly, whereas warm-season grasses were clipped at 4.5 cm twice weekly. The threshold volumetric soil water content (SWC) at which a sharp decline in leaf water potential (ψL) occurred was higher for tall fescue than for warm-season grasses. Buffalograss exhibited the lowest and tall fescue exhibited the highest reduction in leaf pressure potential (ψP) per unit decline in ψL during dry down. Ranking of grasses for magnitude of OA was buffalograss (0.84 MPa) = zoysiagrass (0.77 MPa) > bermudagrass (0.60 MPa) > tall fescue (0.34 MPa). Grass coverage 2 weeks after irrigation was resumed was correlated positively with magnitude of OA (r = 0.66, P < 0.05).
Nitrogen Availability and Fruiting Influence Nitrogen Cycling in Strawberry
Authors: Archbold Douglas D. , MacKown Charles T.
Published: January 2019

As the primary nutrient applied to and used by strawberry, N allocation and cycling within the plant may play an important role in determining plant vigor and productivity. Our objectives were to determine 1) how N availability and fruit production affect N and fertilizer N (FN) partitioning among and within the vegetative tissues of `Tribute' strawberry (Fragaria ×ananassa Duch.) and 2) if the root N pool is temporary storage N. Plants were fed 15N-depleted NH4NO3 (0.001 atom percent 15N) for the initial 8 weeks, then were grown for 12 weeks with or without NH4NO3 with a natural 15N abundance (0.366 atom percent 15N), and were maintained vegetative or allowed to fruit. The vegetative tissues were sampled at 6 and 12 weeks. Neither N availability or fruiting had consistent effects on dry mass (DM) across all tissues at 6 or 12 weeks. At 6 weeks, the total N content of all tissues except the roots were higher with continuous N than with no N. Nitrogen availability was the dominant treatment effect on all plants at 12 weeks; continuous N increased leaflet, petiole, and total vegetative DM and total N of all tissues. Insoluble reduced N (IRN) was the major N pool within all tissues at 6 and 12 weeks regardless of treatment. Fruiting inhibited root growth and N accumulation at 6 weeks but had little effect at 12 weeks. The roots were a strong dry matter and N sink from 6 to 12 weeks. The FN pools, from the 15N-depleted FN supplied during the initial 8 weeks, exhibited changes similar to those of total N in plants not receiving N, in contrast to plants receiving continuous N where total leaflet and petiole N content increased while FN content declined. Total FN per plant declined nearly 26% over 12 weeks; the decline was greater in plants receiving N continuously than in those not receiving N, but the magnitude of the decline was not affected by fruiting. Increasing atom percent 15N values, primarily in plants receiving continuous N after the initial 8 weeks of receiving 15N-depleted FN, indicated that N cycling occurred through all tissues and N pools, proportionally more in the soluble reduced N pool but quantitatively more in the IRN pool. The root N pool was not a “temporary” N storage site available for re-allocation to other tissues, although N cycling through it was evident. Rather, leaflet N was primarily remobilized to other tissues.
Effects of Chilling on Respiration and Induction of Cyanide-resistant Respiration in Seedling Roots of Cucumber
Authors: Reyes Eleazar , Jennings Paul H.
Published: January 2019

The effects of chilling stress on respiration and induction of the alternative pathway (AP) were investigated with roots of 3-day-old cucumber seedlings (Cucumis sativus L.) grown at 26 °C and then chilled at 2, 10, or 15 °C for 24, 48, 96, 144, or 192 hours. Oxygen uptake by roots exposed to 2 °C was significantly lower than by 10 or 15 °C-treated roots, and the inhibition of oxygen uptake in the presence of SHAM (salicylhydroxamic acid) increased from 29% in unchilled tissue to 60% after 96 hours of treatment. At 10 and 15 °C, the capacity of the AP was nearly double that of the unchilled control and the 2 °C-treated seedlings. A 24 hours, postchilling treatment at 26 °C resulted in greater oxygen uptake at all temperatures as treatment time increased up to 96 hours. At 2 °C, the capacity of the AP was significantly reduced below the level of the 10 and 15 °C-treated tissue and the untreated control. The activity of the AP became fully activated by 96 hours in roots chilled at 2 °C. Results suggest that the capacity of the AP can be affected by low-temperature treatments, and exposure to 2 °C for up to 96 hours leads to a significant loss in capacity of the AP.
Year-to-year Consistency of Harvest Data in Raspberry Breeding Plots
Authors: Moore Patrick P.
Published: January 2019

Harvest data from the first and second harvest seasons were compared for 264 plots in six red raspberry (Rubus idaeus L.) plantings established from 1987 to 1992 to determine year-to-year consistency of harvest data. Midpoint of harvest had the largest correlation coefficient (r = 0.81, n = 264), followed by fruit mass (r = 0.76) and fruit firmness (r = 0.47). The relationship between the first and second harvest seasons was weaker for yield (r = 0.33) and percent fruit rot (r = 0.24). Basing the correlation coefficients on genotype means did not greatly improve the consistency of data. Inconsistency of harvest data suggests that selections should not be discarded because of low yields after a single harvest season but should be evaluated for at least 2 years.
Genetic Studies in Peach: Inheritance of Sweet Kernel and Male Sterility
Authors: Werner Dennis J. , Creller Michael A.
Published: January 2019

Inheritance of the sweet kernel trait was studied in F1 and F2 families generated by crossing `Summer Beaut' nectarine (sweet kernel) with `Ellerbe' and `Biscoe' peach. F1 plants showed bitter kernel. Segregation in the F2 fit a 3 bitter : 1 sweet phenotypic ratio, suggesting that sweet kernel is controlled by a single recessive gene, for which the symbol sk is proposed. Sweet kernel (sk) was linked to nectarine (g) at a map distance of 12 cM. Seed bitterness phenotype is controlled by the genotype of the maternal tree and not the genotype of the individual embryo. Inheritance of male sterility derived from plant introduction (PI) 240928 and allelism of male sterile genes found in `Chinese Cling' and `White Glory' were investigated. Analysis of F1, F1 open-pollinated, and BC1 families derived from crossing PI 240928 with six different wild-type cultivars showed that male sterility in PI 240928 is controlled by cytoplasmic factors. Allelism studies showed that the male-sterile gene found in `White Glory' is not allelic to ps found in `Chinese Cling', and hence is designated ps2.
Changes in Alternative Pathway and Mitochondrial Respiration in Avocado in Response to Elevated Carbon Dioxide Levels
Authors: Lange Diana L. , Kader Adel A.
Published: January 2019

Partially ripened avocado [Persea americana (Mill.) cv. Hass] fruit harvested in either June or Aug. 1994 were kept at 10 °C in air (21% O2), 20% CO2 (17% O2, balance N2), or 40% CO2 (13% O2, balance N2) for 7 to 12 days and then were transferred to air at 10 °C for 2 to 3 days. Mitochondrial respiration was stimulated in response to elevated CO2 treatments at 10 °C. A shift to alternative pathway (Alt) respiration occurred on day 4 in experiments using avocados from both harvest dates, with a return to initial levels in only the 20% CO2-treated fruit (June-harvested fruit after return to air). Elevated CO2 at 20 °C decreased the in vitro O2 consumption of isolated mitochondria compared to mitochondria kept in air. The Alt pathway contributed less to the total O2 uptake of CO2-treated mitochondria compared to mitochondria kept in air. The respiratory control ratios of the CO2-treated fruit and mitochondria were higher and lower, respectively, than the air controls. Induction of 33 to 37 kD proteins (corresponding to the size of the alternative oxidase proteins) occurred in avocados after 4 days in 40% CO2. These results indicate that elevated CO2 has various effects depending on concentration, duration and temperature of exposure, and mitochondrial function of avocado fruit, such as increased and altered respiratory oxidation and up-regulation of alternative oxidase proteins.
The Effect of High Carbon Dioxide at Low Temperature on Ribulose 1,5-Biphosphate Carboxylase and Polygalacturonase Protein Levels in Cherimoya Fruit
Authors: Escribano María I. , Del Cura Begoña , Muñoz Teresa , Merodio Carmen
Published: January 2019

The effect of short-term high CO2 on maintaining postharvest cherimoya (Annona cherimola Mill.) fruit quality during storage at low temperature was analyzed. Pretreatment with an atmosphere of 20% CO2 and 20% O2 for 3 days retained fruit firmness and prevented an increase in the immunodetected levels of polygalacturonase-related protein during storage at 6 °C. Color scale values, chlorophyll content, and levels of the immunoreactive large subunit of ribulose 1,5-biphosphate carboxylase protein were higher in treated than in air-stored fruit. Short-term high CO2 treatment had a long residual effect at low temperature and improved storage life by preventing fruit softening and delaying senescence-like responses in green peel of cherimoya fruit tissues.
Genetic Linkage with the Shiny Pod Character (ace) in Common Bean
Authors: Bassett Mark J.
Published: January 2019

Linkage relationships between the locus for shiny pods (ace) and the loci for reclining foliage (rf) and pink (vlae) or white (v) flower color were studied in several crosses among common bean (Phaseolus vulgaris L.) parents. Florida dry bean breeding line 5-593 (Ace Rf V.) was crossed with F3 ace/ace Rf/rf V/vlae, and data were taken in F2. Selections from the previously mentioned F2, viz., F3 ace Rf V, F3 ace rf vlae plant no. 1 and F3 ace rf vlae plant no. 2, were backcrossed to 5-593. Data were taken in F2 on segregation for pod, foliage, and flower characters. Linkage between Ace and V was 37 map units (cM), and linkage between Ace and Rf was 31 cM. A revised estimate for the linkage between Rf and V was 11 cM. The map orientation for linkage group VII is ace -31-rf-11-V.
Relationship between Leaf Water Potential and Gas Exchange Activity at Different Phenological Stages and Fruit Loads in Peach Trees
Authors: Marsal Jordi , Girona Joan
Published: January 2019

Relationships between midday (Ψmd) and predawn (Ψpd) leaf water potential, stomatal conductance (gs), and net CO2 assimilation rate (A) were determined at different fruit growth stages and for 2 years with different fruit loads in a `Sudanell' peach [Prunus persica (L) Batsch] plot subjected to two regulated deficit irrigation (RDI) strategies plus a control irrigation treatment. A postharvest RDI (PRDI) treatment was irrigated at 0.35 of the control after harvest. The second treatment (SPRDI) applied RDI during Stage II, the lag phase of the fruit growth curve, at 0.5 of the control and postharvest at 0.35 of the control. The control treatment and the PRDI and SPRDI when not receiving RDI were irrigated at 100% of a modified Penman crop water use calculation (ETo) in 1994, a full crop year, and 80% in 1995, a year of nearly zero crop. In 1995, with 80% of the 1994 irrigation rate and no crop, the Ψmd was higher, probably because of the lower crop load, while Ψpd was lower, probably because less water was applied to the soil. The relationship of gs and A with Ψmd during Stage II was steeper than during postharvest. Low Ψmd was not indicative of a depression in gs and A in Stage III. Osmotic leaf water potential at turgor loss (Ψπ0) as derived from pressure-volume curves was more negative during Stage III and postharvest (about -2.9 MPa) than in Stage II (about -2.7 MPa). The Ψmd measurements together with Ψπ0 determinations seemed to be more useful to characterize peach tree water status than Ψpd under soil water deficits because of their better relationship to midday stomatal closure.
Composts from Various Municipal Solid Waste Feedstocks Affect Vegetable Crops. II. Growth, Yields, and Fruit Quality
Authors: Roe Nancy E. , Stoffella Peter J. , Graetz Donald
Published: January 2019

Compost (biosolids and yard trimmings at 134 t·ha-1) was applied to a sandy field soil with fertilizer at 0%, 50%, or 100% of the grower's standard rate (71N-39P-44K kg·ha-1 broadcast and 283N-278K kg·ha-1 banded in bed centers). Raised beds were constructed and covered with polyethylene mulch, and `Elisa' bell peppers (Capsicum annuum L.) were transplanted into the plots. Foliage samples taken at early harvest indicated that leaf N concentrations increased and Cu concentrations decreased with increasing fertilizer rates. Leaf concentrations of P, K, Ca, and Mg increased and Cu decreased in plots amended with compost. Marketable pepper yields from plants grown in plots amended with compost were 30.3, 35.7, and 31.1 t·ha-1 in plots with 0%, 50%, and 100% fertilizer rate, respectively. Without compost, yields were 19.8, 31.1, and 32.0 t·ha-1 with 0%, 50%, and 100% fertilizer rate. `Valient' cucumbers (Cucumis sativus L.) were seeded through the same polyethylene mulch into the previous pepper plots. Marketable cucumber yields were not affected by residual fertilizer, but were higher (26.8 t·ha-1) in plots amended with compost than without compost (22.7 t·ha-1). In a second experiment, a biosolids-yard trimming-mixed waste paper (MWP) compost and a biosolids-yard trimming-refuse-derived fuel (RDF) compost were applied at 0 or 134 t·ha-1 with fertilizer at 0%, 50%, or 100% fertilizer rates, respectively. With no fertilizer, total yields from pepper plants were higher in plots amended with composts than without composts. In 50% fertilizer plots, yields were similar between compost treatments. At 100% fertilizer rate, yields with MWP compost were significantly higher than yields with RDF compost or with no compost. In plots without fertilizer or with 50% fertilizer rates, mean fruit size (g/fruit) was largest with MWP compost, intermediate with RDF compost, and smallest without compost. With 100% fertilizer, mean fruit size was larger with either compost than without compost. Composts combined with low rates of fertilizer generally produced higher pepper yields than other treatments. Residual compost increased yields of a subsequent cucumber crop. Yields from pepper plants without fertilizer were higher when soil was amended with composts with added MWP or RDF, but, with fertilizer, yields were similar or only slightly increased.
Effect of Applied Iron Concentration on Growth and Phylloclade Marginal Chlorosis of Holiday Cactus (Schlumbergera sp.)
Authors: Ramirez Dario , Lang Harvey J.
Published: January 2019

Two studies were conducted to determine the effect of applied Fe concentration on the occurrence of phylloclade marginal chlorosis in holiday cactus. Schlumbergera sp. `White Christmas', `Twilight Tangerine', `Christmas Charm', and `Lavender Doll' were grown in either solution culture or a peat-based medium and supplied with a nutrient solution containing Fe-EDTA at either 0, 0.18, 0.36, 0.54, or 0.72 mm. Growth decreased while marginal chlorosis increased on all cultivars as Fe-EDTA treatment levels increased. Phylloclade marginal chlorosis developed more severely and consistently in plants grown in peat-based media versus solution culture. Marginal chlorosis and accumulation of Fe in the potting medium occurred very slowly, and first symptoms were not observed until after about 2 months of treatment. Symptomatic phylloclade tissue had a greater Fe concentration than corresponding asymptomatic phylloclade tissue. Cultivars varied in tissue Fe concentration and symptom severity across Fe-EDTA treatments. There were no significant correlations in other tissue micronutrient concentrations with either Fe treatment or symptom development. The pH of either the culture solution or peat-based medium leachate did not change significantly throughout either study, and there were no significant amounts of Fe+2 detected in solution. Chemical name used: ferric ethylenediaminetetraacetic acid, monosodium salt (Fe-EDTA).
Androgenesis in Capsicum annuum L.—Effects of Carbohydrate and Carbon Dioxide Enrichment
Authors: Dolcet-Sanjuan Ramon , Claveria Elisabet , Huerta Agustin
Published: January 2019

A new and simple protocol for androgenesis in bell pepper is described. The initial medium, a modification of Nitsch and Nitsch's H medium, consisted of a two-phase system of semi-solid and liquid medium and contained maltose as carbon source. The total number of embryos formed was greater with maltose at 40 g·L-1, but embryos developed better at 10 to 20 g·L-1. Depending on the genotype, the number of embryos and plants recovered ranged from 3 to 750 and 0.25 to 8, respectively, per 100 flowers. Further increases in the number of embryos (up to 3561 per 100 flowers) and plants (up to 23 per 100 flowers) could be attained by flushing cultures with air enriched with CO2 at 900 μL·L-1. The ploidy level and the microspore origin of the recovered plants were determined by flow cytometry and zymograms for isocitrate dehydrogenase. Nearly 65% of the acclimated plants had undergone spontaneous doubling of the chromosome number, as confirmed by flow cytometry of leaf nuclei. Isocitrate dehydrogenase zymograms demonstrated that plants originated from microspores and that the two parental alleles were equally represented among the haploid and dihaploid plants.
Sensitivity of Shoots and Roots of Young Watermelon Plants to End-of-day Red and Far-red Light
Authors: Graham Heather A. Hatt , Decoteau Dennis R.
Published: January 2019

The sensitivity of shoots and roots to end-of-day (EOD) red (R) or far-red (FR) light on growth of `Sugar Baby' watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] was investigated. Plants were grown in full-strength Hoagland solution and treated for 14 days to 15 minutes EOD light in trial 1 and in half-strength Hoagland solution and treated for 10 days to EOD light in trial 2. Exposing shoots to EOD FR resulted in elongated petioles of leaves 1 to 3 (as counted from the cotyledons), internodes 1 to 3, and total stem length in both trials. Exposure to EOD FR resulted in increased stem and petiole dry mass in trial 1, whereas EOD FR resulted in increased root and leaf dry mass in trial 2. EOD FR exposure of roots increased the length of petiole 4 in trial 1. In general, shoots were more responsive than roots to the growth-regulating effects of EOD FR.
Using Isozyme Polymorphisms for Identifying and Assessing Genetic Variation in Cultivated Pawpaw [Asimina triloba (L.) Dunal]
Authors: Huang Hongwen , Layne Desmond R. , Peterson R. Neal
Published: January 2019

The utility of isozyme phenotypes for identifying and determining genetic variation in pawpaw cultivars was studied using isoelectric focusing in thin-layer polyacrylamide gels. Based on a sample of 32 clones (cultivars and advanced selections) and 23 enzyme systems, 7 enzymes were found to be polymorphic, involving 9 polymorphic loci [acid phosphatase (ACP), dihydrolipoamide dehydrogenase (DDH), malic enzyme (ME), phosphoglucoisomerase (PGI), phosphoglucomutase (PGM), peroxidase (PRX), and shikimate dehydrogenase (SKD)]. Altogether these 9 loci and 32 clones yielded 28 multi-locus isozymic phenotypes useful for cultivar identification; 24 of the 32 clones were uniquely identified. The allozyme variation in these clones has the average of other long-lived woody perennials of widespread geographic range in temperate regions with insect-pollinated outcrossing breeding systems, secondary asexual reproduction, and animal-dispersed seed. Genetic differentiation among these pawpaw clones, measured by Nei's distance, D, was substantial: 496 pairwise comparisons of genetic distance among the 32 clones indicated that they differed on average of D = 0.068 ± 0.04 and ranged from 0 to 0.188. Cluster analysis (UPGMA) produced a most likely division of the 32 clones into 7 groups; however, these groups did not conform to known pedigree relations. Additional polymorphic enzymes are needed for accurate allozyme-based genetic discrimination.
Dibutylurea Reduces Photosynthesis, Growth, and Flowering of Petunia and Impatiens
Authors: van Iersel Marc W. , Bugbee Bruce
Published: January 2019

Dibutylurea (DBU), a breakdown product of benomyl, may be partially responsible for the previously reported phytotoxicity of the fungicide Benlate DF. We quantified the effect of DBU on the growth of two popular bedding plant species, petunia (Petunia × hybrida) and impatiens (Impatiens wallerana Hook. f.). DBU reduced photosynthesis of both species, and its effect strongly depended on the amount of DBU applied. The effects of DBU were most apparent 2 to 4 days after treatment, at which time 1.20 g·m-2 (corresponding to 10% DBU in Benlate DF at maximum labeled drench rate) inhibited photosynthesis completely. DBU also decreased flower number and caused marginal necrosis. DBU effects were more pronounced in low relative humidity. Benlate DF containing 3.1% DBU and an equivalent amount of reagent grade DBU had similar effects on photosynthesis and petunia necrosis. Our results showed that DBU is responsible for at least part of the phytotoxic symptoms that can be caused by Benlate DF. However, other ingredients or breakdown products may also contribute to the phytotoxic symptoms of Benlate DF.
Low Oxygen and Elevated Carbon Dioxide Atmospheres Inhibit Ethylene Biosynthesis in Preclimacteric and Climacteric Apple Fruit
Authors: Gorny James R. , Kader Adel A.
Published: January 2019

Autocatalytic C2H4 biosynthesis in preclimacteric apple fruit (Malus domestica Borkh. `Golden Delicious') was prevented by storage in atmospheres of 20% CO2-enriched air (17% O2 + 63% N2) or 0.25% O2 (balance N2). In preclimacteric fruit, both treatments inhibited C2H2 biosynthesis by suppressing expression of ACC synthase (ACC-S) at the mRNA level. ACC oxidase (ACC-O) mRNA abundance and in vitro enzyme activity also were impaired by these treatments. However, the conversion of ACC to C2H4 never became the rate limiting step in C2H4 biosynthesis. C2H4 biosynthesis also was effectively inhibited in climacteric apple fruit kept in air + 20% CO2 or 0.25% O2. Climacteric apples also exhibited suppressed expression of ACC-S at the mRNA level, while ACC-O transcript abundance, enzyme activity, and protein abundance were reduced only slightly. ACC-S is the key regulatory enzyme of C2H4 biosynthesis and is the major site at which elevated CO2 and reduced O2 atmospheres inhibit C2H4 biosynthesis, irrespective of fruit physiological maturity. Chemical names used: 1-aminocyclopropane-1-carboxcylic acid (ACC).
Influences of Cross- and Self-pollination on Peroxidase Activities, Isozymes, and Histological Localization during `Sharpblue' Blueberry Fruit Development
Authors: Huang Y.H. , Lang G.A. , Johnson C.E. , Sundberg M.D.
Published: January 2019

Five-year old `Sharpblue' southern highbush blueberry plants (Vaccinium corymbosum L.) were self- and cross-pollinated (`O'Neal') to study peroxidase (POD) activity, isozyme patterns, and histological localization during fruit development. Cross-pollination resulted in larger and earlier-ripening fruit. Activities of soluble and bound POD were very high during fruit growth period I, with peaks at 10 and 20 days after self- and cross-pollination. Activity was much higher for cross-pollinated fruit. During fruit growth period II, POD activities were low in both pollination treatments. During ripening, soluble POD increased, then declined in both treatments. Bound POD activities increased during the color transition from blue to dark blue, with the increase greater in self-pollinated fruit. Banding patterns of soluble and bound POD isozymes and their histological localization varied by pollination treatment as well as fruit developmental stage. During fruit ripening, soluble POD activity appeared to be associated with color transition from light blue to blue, while bound POD activity appeared to be associated with color transition from blue to dark blue.
Pollen Sources Influence Early Fruit Growth of Southern Highbush Blueberry
Authors: Huang Y.H. , Johnson C.E. , Lang G.A. , Sundberg M.D.
Published: January 2019

Ovule abortion occurred between 5 and 10 days after pollination (DAP) in self- and cross-pollinated `Sharpblue' blueberry (Vaccinium corymbosum L.) fruit. More ovule abortion occurred with self-pollination (35%) than with cross-pollination (22% for `Sharpblue' × `O'Neal' and 29% for `Sharpblue' × `Gulfcoast'), and there were more poorly developed ovules with self-pollination (88.1%) than with cross-pollination (× `O'Neal', 33.6%; × `Gulfcoast' 50.8%). The increase in ovule area correlated exponentially with fruit growth during early developmental stages, regardless of pollination treatment. However, cross-pollination resulted in significantly greater ovule area and fruit mass during early fruit development as well as at ripening. Ovule area was maximum at 25 to 30 DAP for both pollination treatments, followed by exponential fruit growth (stage III). Cross-pollination resulted in greater fruit growth and a shorter stage III. At 10 DAP, ovules from cross-pollination were larger than those from self-pollination, suggesting that cross-pollination initiated ovule growth immediately after fertilization. This research suggests that southern highbush blueberry fruit growth and development is intimately associated with ovule growth and development, which is affected by pollen sources.
Floral Morphology and Development of `Sharpblue' Southern Highbush Blueberry in Louisiana
Authors: Huang Y.H. , Johnson C.E. , Sundberg M.D.
Published: January 2019

Floral morphology and differentiation of `Sharpblue' southern highbush blueberry (Vaccinium corymbosum L.) were studied under natural growing conditions. There was no rest period during floral development of `Sharpblue' blueberry in Louisiana. Basal florets were already present within a racemic inflorescence in early September. All floral and reproductive organs were clearly visible in early December. Microspores and pollen grains were observed in mid- and late-January, respectively. Megasporocytes, two-cell, four-cell, and seven-cell embryo sacs were found to be simultaneously present in developing ovules in late January, suggesting that megasporogenesis and megagametogenesis in `Sharpblue' blueberry are asynchronous.
Response to Family Selection for Field Resistance to Verticillium dahliae in California Strawberries
Authors: Shaw Douglas V. , Gubler W. Douglas , Hansen John , Larson Kirk D.
Published: January 2019

Strawberry genotypes were retained from biparental progenies previously identified as either relatively susceptible or resistant to wilt caused by Verticillium dahliae based on a phenotypic resistance score. Runner plants from these selected genotypes were inoculated with a conidial suspension containing a mixture of five isolates obtained from symptomatic strawberry plants at 106 conidia/mL, then scored for disease symptoms. Genotypes from resistant progenies had significantly higher phenotypic resistance scores (1 = severe symptoms, 5 = no detectable symptoms) than those from susceptible progenies (4.15 vs. 2.23), and there also was a correlated selection response for the percent plants severely stunted or dead (26.4 and 69.1 for resistant and susceptible selections, respectively). Comparisons of the resistance scores for selected groups with those for the original parents (2.76) indicated that selection had changed relative resistance significantly in both directions and that realized response had been 24% to 43% larger than predicted for selection in both directions. Although several of the selections from resistant progenies were highly susceptible, five of the 21 resistant selections had resistance scores outside the range of the original parents, representing possible transgressive segregants. This comparison is limited by the precision with which individual resistance scores are estimated and by the scope of the disease symptoms in this trial. Detecting genotypes with sufficient resistance ultimately will depend on development of screening methods with greater sensitivity than those used here.
Storage-temperature-dependent Time Separation of Softening and Chlorophyll Loss from the Autocatalytic Ethylene Pathway and Other Ripening Events of `Anjou' Pears
Authors: Gerasopoulos D. , Richardson D.G.
Published: January 2019

Mature `Anjou' pears (Pyrus communis L.) continuously stored at 20 °C or -1 °C before transfer to 20 °C exhibited differences in the sequence of ripening events up to 100 days. Pears continuously held at 20 °C showed little change in ripening characteristics (chlorophyll, firmness, titratable acidity) for 14 to 28 days, then these characteristics decreased at a daily rate of 1.4% thereafter. A 40% increase in soluble polyuronides paralleled the firmness loss, while ACC did not exceed 0.5 nmol·g-1 until the 84th day, and internal ethylene did not exceed 0.2 μL·L-1 until after 90 days, whereas ACC oxidase activity (and total protein) peaked after 63 days. `Anjou' pears stored at -1 °C showed no changes in chlorophyll, firmness, protein, or total polyuronides for at least 84 d. Despite essentially no change in firmness during -1 °C storage, there was a slow but steady increase (≈15 %) in soluble polyuronides. ACC oxidase activity, expressed as ethylene production, rose to 71 nL·g-1·h-1 and the ACC content increased to almost 1.0 nmol·g-1 by the 84th day. Internal ethylene slowly increased and levelled to 1 μL·L-1 by the 56th day. Satisfaction of a chilling requirement thus appears to favor the development of ethylene synthesis capacity, which on transfer from cold storage to higher temperatures results in enough internal ethylene to rapidly drive the associated ripening mechanisms. Fruit for which the chilling requirement (≥70 days at -1 °C) was met softened in response to accelerated internal ethylene production on transfer to 20 °C for 7 days. However, pears that were not chilled or partially chilled did not sustain the increased ACC levels or ACC oxidase activity. Chemical name used: 1-aminocyclopropane-1-carboxylate (ACC).
Allelism Tests Involving Two Genes, ers and ers-2, that Restrict Partly Colored Seedcoat Expression in Common Bean
Authors: Bassett Mark J.
Published: January 2019

An inheritance study was conducted with genetic stocks constructed in the genetic background of the recurrent parent 5-593, a Florida dry bean (Phaseolus vulgaris L.) breeding line with black seeds and purple flowers and genotype P T Z l+. The genetic stocks, t ers ers-2 BC3 5-593 (pure white seeds), t virgarcus BC3 5-593, and t BC2 5-593 self-colored were constructed by backcrossing selected recessive alleles for partly colored seedcoats into 5-593. The cross t ers ers-2 BC3 5-593 × t BC2 5-593 self-colored was studied in F1, F2, and F3. The observed data supported the hypothesis that ers is a synonym for z and that ers-2 is a synonym for a new allele (lers) at the L locus. The cross t ers ers-2 BC3 5-593 × t virgarcus BC3 5-593 was studied in F1 and F2 progeny, and the results confirmed the hypothesis of allelism between ers and z. `Thuringia' (pure white seedcoats) with genotype P t z L was crossed with t ers ers-2 BC3 5-593, t virgarcus BC3 5-593 and t BC2 5-593 self-colored. The cross `Thuringia' (P t z L) × t ers ers-2 BC3 5-593 was studied in F1 and F2 and supported the hypothesis that lers is an allele at L. The results of the other two test crosses are discussed. The gene ers-2 is a new recessive allele at L, for which the new symbol lers is proposed. Thus, the dominance order at the L locus is L > l+ > lers, where l+ is the null allele at L found in 5-593. The l+ allele does not restrict the colored area of a partly colored seedcoat and is hypothetically the wild-type allele at L.
Pollination Requirements of Three Highbush Blueberry (Vaccinium corymbosum L.) Cultivars
Authors: MacKenzie Kenna E.
Published: January 2019

The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.
Factors and Time of Sample Collection for Correlating Storage Potential of `McIntosh', `Spartan', and `Golden Delicious' Apples
Authors: Wolk William D. , Lau O.L. , Neilsen G.H. , Drought Brian G.
Published: January 2019

A study was undertaken to identify key factors associated with storage disorders in three commercially important apple cultivars in British Columbia and to determine how early in the season associations could be measured. Fruit mass, density, and concentrations of N, P, K, Ca, Mg, and dry matter were determined for `McIntosh', `Spartan', and `Golden Delicious' apples (Malus ×domestica Borkh) from ≈30 commercial orchards 9, 6, 3, and 0 weeks before harvest. Storage samples were collected at commercial harvest and evaluated for the development of internal breakdown (`McIntosh' and `Spartan') or bitter pit (`Golden Delicious') after 4 and 6 months of 0 °C air storage. Mass and [Ca] and the mass/[Ca] and [K]/[Ca] ratios were the factors most often significantly correlated with storage disorders within each year for all three cultivars. Correlations were as frequently significant 6 and 3 weeks before harvest as they were at harvest. Mass of `McIntosh' and `Spartan' was the only variable consistently related with breakdown in all 3 years of the study. There were no variables with a consistent relationship to bitter pit in `Golden Delicious'. Fruit [Ca] was associated with the relative levels of disorders within years but could not be associated with specific levels of disorders across all years.