bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations in Anatomy and Ultrastructure of Pecan Leaves Treated with Propiconazole during Shoot Expansion
Authors: Wetzstein Hazel Y. , Richardson Elizabeth A. , He Yi
Published: January 2019

Propiconazole, a triazole fungicide, has been reported to inhibit leaf expansion in pecan [Carya illinoensis (Wangenh.) K. Koch] trees when applied under field conditions. This study was conducted to determine the effect of propiconazole on pecan leaf morphology and structure using light and transmission electron microscopy. Mature pecan trees were sprayed once or three times per week from budbreak to pollen maturity. Fungicide sprays resulted in significantly reduced leaf area. Compared to controls, leaves from propiconazole-treated shoots had alterations in cell arrangement characterized by more tightly packed palisade parenchyma cells with fewer intercellular spaces; neither leaf thickness nor palisade or spongy layer thickness were affected. Propiconazole caused modifications in the chloroplasts, with a tendency for internal membranes to be less defined, and for thylakiods to exhibit less stacking. The extent of structural changes was related to fungicide dosage. Results show that propiconazole applications during leaf development can inhibit leaf expansion and modify cellular organization of the mesophyll cells. Chemical name used: 1-[[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl] methyl]-1H-1,2,4-triazole (propiconazole).
Thinning `Fuji' Apple Blossoms with Synthetic Auxins (MCPB-ethyl or NAA) and Ethephon with or without Postbloom Thinning with Carbaryl
Authors: Guak Sunghee , Beulah Michael , Looney Norman E. , Fuchigami Leslie H.
Published: January 2019

Three experiments were conducted at two locations, two at Summerland, British Columbia, Canada and one at Corvallis, Ore., to evaluate synthetic auxins (MCPB-ethyl or NAA) and ethephon as blossom thinners for `Fuji' apple [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.]. These experiments also involved application of carbaryl at 1000 mg·L-1 in the postbloom period. All blossom thinners were sprayed at 85% full bloom while carbaryl was applied at 11-mm fruit diameter. Within these experiments, MCPB-ethyl at up to 20 mg·L-1 or NAA at up to 21 mg·L-1 increased whole flower cluster removal linearly with rate; however, with the Corvallis experiment MCPB-ethyl failed to result in any thinning. Neither auxin treatment consistently reduced fruit set on the remaining clusters, resulting in “clustering”. Bloom-time application of ethephon at 100 mg·L-1 with NAA further reduced crop load. Carbaryl reduced total crop load by increasing both whole cluster removal and number of sites with a single fruit. Return flowering was not improved by the auxin treatments except where there was very excessive crop reduction. Ethephon or carbaryl promoted return flowering with the carbaryl effect being more pronounced. However, this carbaryl effect was significantly countered by the bloom-time auxin whereas ethephon overcame the negative effects of the auxin treatments. The combined use of ethephon and carbaryl was effective in terms of both crop reduction and return flowering benefits. Chemical names used: 1-naphthyl N-methylcarbamate (carbaryl); 2-chloroethylphosphonic acid (ethephon); ethyl 4-(4-chloro-2-methylphenoxy) butanoate (MCPB-ethyl); and 2-(1-naphthyl) acetic acid (NAA).
Herbicidal Actions of Root-Applied Glufosinate Ammonium on Tomato Plants
Authors: You Wenqi , Barker Allen V.
Published: January 2019

The herbicidal action of foliar applications of glufosinate-ammonium (GLA) is due to toxic accumulation of unassimilated NH4+ in leaves; however, the effects of root-applied GLA on NH4+ accumulation and plant growth are unknown. In a dose-response hydroponics experiment, tomato (Lycopersicon esculentum Mill.) plants were grown in nitrate-based solutions with GLA added at 0, 6, 12, 25, or 50 mg·L-1. To observe plant responses to an exogenous NH4+ source with herbicide-induced responses, plants were grown in an NH4+-based solution without GLA addition. At 6 days after treatment (DAT), GLA in solution at 25 mg·L-1 produced partial leaf wilting, chlorosis, and necrosis of foliage, and at 50 mg·L-1, plants were fully wilted and necrotic. Ammonium (NH4+-N) concentration in shoots at 6 DAT increased from 0 to 6 mg·g-1 fresh weight with increasing GLA in the nutrient solution. Ethylene evolution doubled (from 4 to 8 nL·g-1·h-1, fresh weight) with increases in GLA from 0 to 25 mg·L-1 but declined with apparent plant death with GLA at 50 mg·L-1. Other treatments, including NH4+ nutrition, did not induce toxicity symptoms in leaves or give increases in NH4+ accumulation or ethylene evolution during the 6 days of the experiment. In a time-course experiment, tomato plants treated with GLA at 25 mg·L-1 were chlorotic at 4 DAT. Ethylene evolution (fresh weight basis) rose from an initial rate of 2.6 nL·g-1·h-1 to 8.3 nL·g-1·h-1 after 4 days. At 9 DAT, all plants receiving this treatment died. In the time-course experiment, an exogenous NH4+ treatment caused a slight inhibition in shoot fresh weight relative to NO3- nutrition with no GLA but caused no visible symptoms and only slight enhancements in NH4+ accumulation and ethylene evolution over the 9-day period. Following GLA treatment, NH4+ accumulated in the shoots and increased sharply with time, whereas exogenous NH4+ led to NH4+ accumulation primarily in roots. Results suggest that GLA was absorbed by roots and translocated to shoots, where it initiated accumulation of NH4+ and ethylene evolution as indications of herbicidal action. Chemical name used: glufosinate-ammonium, GLA.
Drought Responses among Seven Southwestern Landscape Tree Taxa
Authors: Balok Coye A. , Hilaire Rolston St.
Published: January 2019

Identification of tree taxa that can thrive on reduced moisture regimes mandated by xeriscape programs of the southwest United States could be facilitated if responses to drought of those taxa are determined. Leaf water relations, plant development, and cuticular wax content of seven taxa maintained as well-irrigated controls or exposed to drought and irrigated based on evapotranspiration were studied. Leaf water potential of drought-stressed Fraxinus velutina Torr. (Arizona ash), Koelreuteria paniculata Laxm. (golden rain tree), Quercus macrocarpa Michx. (bur oak), and Quercus muehlenbergii Engelm. (chinkapin oak) were lower at predawn than the controls. Drought-stressed plants of F. velutina, K. paniculata, and Quercus lobata Née (California white oak) had more negative midday water potential than the control plants. Drought reduced stomatal conductance to as little as 17%, 23%, and 45% of controls in F. velutina, K. paniculata, and Q. macrocarpa, respectively. Drought-stressed plants of F. velutina, K. paniculata, Q. macrocarpa, and Q. muehlenbergii had reduced transpiration rates. Fraxinus velutina had both the highest net assimilation rate (NAR) and relative growth rate (RGR) regardless of irrigation treatment. Mean specific leaf weight (dry weight (DW) of a 1-cm2 leaf disc divided by the weight), trichome density, stomatal density, leaf thickness, and cuticular wax content varied among species but not between irrigation treatments. Leaves of Q. buckleyi Buckl. (Texas red oak) had one of the highest stomatal densities, and also had leaves which were among the waxiest, most dense, and thickest. Abaxial leaf surfaces of F. velutina were the most pubescent. Across species, drought led to lower ratios of leaf surface area to root DW, and leaf DW to root DW. Quercus buckleyi plants subjected to drought had the highest root to shoot DW ratio (3.1). The low relative growth rate of Q. buckleyi might limit widespread landscape use. However, Q. buckleyi may merit increased use in landscapes on a reduced moisture budget because of foliar traits, carbon allocation patterns, and the relative lack of impact of drought on plant tissue water relations.
Field Resistance to Fire Blight in a Diverse Apple (Malus sp.) Germplasm Collection
Authors: Luby James J. , Alspach Peter A. , Bus Vincent G.M. , Oraguzie Nnadozie C.
Published: January 2019

Incidence and severity of fire blight [Erwinia amylovora (Burr.) Winslow, Broadhurst, Buchanan, Krumwiede, Rogers, and Smith] following field infection were recorded using families resulting primarily from open-pollination of Malus sylvestris (L.) Mill. var.domestica (Borkh.) Mansf. cultivars and a few other Malus Mill. sp. The families were structured as three sublines, planted in three successive years (1992 to 1994), of a diverse population of apple germplasm established at HortResearch, Hawkes Bay, New Zealand. The incidence of fire blight varied among the sublines with the oldest planting exhibiting more fire blight. Flowering trees were more likely to be infected than nonflowering trees, in terms of both incidence and severity. Furthermore, the level of fire blight was related to flowering date, with later flowering trees having higher levels. Thus, family means and narrow-sense heritability estimates were computed after first adjusting the fire blight score for flowering date by fitting a linear model. Provenance of origin of the maternal parent explained little variation except that M. sieversii Lebed. families were more resistant than M. sylvestris var. domestica families in one subline. Family means computed using all trees, and those from only flowering trees were highly correlated. Families from open-pollination of M. honanensis Rehder and M. xhartwiggii Koehne females were among the more susceptible. Those from several European M. sylvestris var. domestica cultivars as well as from M. baccata (L.) Borkh. and M. toringoides (Rehder) Hughes females were among the more resistant families. Narrow-sense heritability estimates ranged from 0.05 to 0.85 depending on the subline, with most estimates between 0.12 and 0.36. They were higher in the two older sublines that consisted primarily of open-pollinated families from M. sylvestris var. domestica, and lower in the younger subline that consisted primarily of M. sieversii, due to lower incidence and severity in the latter subline. Breeders who consider potential complications of juvenility, tree size, and flowering date in relation to infection periods should be able to exploit field epidemics to perform effective selection.
Genetic Interactions of Pillar (Columnar), Compact, and Dwarf Peach Tree Genotypes
Authors: Scorza Ralph , Bassi Daniele , Liverani Alessandro
Published: January 2019

A study was conducted to determine genetic control of the columnar or pillar (PI) growth habit, and to evaluate the effects of interactions of various genes that influence peach [Prunus persica (L.) Batsch (Peach Group)] growth habit. The PI habit (brbr) examined in this study was inherited as a monogenic trait expressing incomplete dominance. The heterozygous Brbr derived from crosses between standard (ST) and PI genotypes was recognized as an upright (UP) tree with narrower branch angles than ST trees but wider than PI trees. The combination of brbr and brachytic dwarf (DW) (dwdw) produced dwarf-pillar (DWPI) trees. The effects of the heterozygous Brbr in combination with dw and/or compact (CT) (Ct) could not be recognized by visual observation. Compact pillar (CTPI) trees resulted from the expression of Ct_ brbr. These trees were distinguished from globe-shaped (GL) trees (Ct_Brbr) by the more upright growth habit of the CTPI trees. This genetic study highlights the genetic plasticity of tree growth habit in peach. The investigation of novel growth habits extends our concept of the peach tree. Some growth habits such as PI may have commercial potential for high-density peach production systems. Others, such as DWPI and CTPI may have potential as ornamentals.
Comparative Carotenoid Accumulation and Retention in Near-isogenic rprp and RPRP Inbred Carrot Lines
Authors: Poon W.Y.L. , Goldman I.L.
Published: January 2019

The rp allele causes a significant reduction in total carotenoid pigmentation in carrot (Daucus carota L.) roots. The objective was to investigate the effect of rp on the composition, accumulation, and retention of carotenoids in two near-isolines of carrot, W266RPRP and W266rprp, during vegetative growth and postharvest storage. Field experiments were conducted during 1996 and 1997 in which roots were sampled weekly from 62 to 100 days after seed-sowing and biweekly during postharvest storage at 4 °C up to 386 days after sowing. Linear increases in total carotenoid concentration were observed for W266RPRP and W266rprp during vegetative growth. The average daily rate of increase in total carotenoid concentration in W266RPRP and in W266rprp was 12.7 and 1.3 mg·g-1 dry weight, respectively. A linear decrease in carotenoid concentration was measured for W266RPRP but not for W266rprp during postharvest storage. At 100 days after sowing, high-performance liquid chromatography analyses showed W266rprp had 20-fold lower concentrations of a-carotene and 50-fold lower concentrations of β-carotene in root tissue compared to W266RPRP. Levels of β-carotene and lutein in the first true leaves were reduced by ≈50% in W266rprp compared to W266RPRP. Results from this investigation suggest that the rp allele affects the concentration of root and foliage carotenoids, as well as the rate of carotenoid accumulation and degradation in carrot roots. The impact of the rp allele is far greater in root tissue than in foliage, suggesting it may act as a transcription factor or structural gene affecting primarily root carotenoid biosynthesis.
Acclimation of Photosynthetic Activity of Zantedeschia `Best Gold' in Response to Temperature and Photosynthetic Photon Flux
Authors: Funnell Keith A. , Hewett Errol W. , Plummer Julie A. , Warrington Ian J.
Published: January 2019

Photosynthetic activity of individual leaves of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. [syn. Richardia pentlandii Wats.] (`Best Gold'), were quantified with leaf expansion and diurnally, under a range of temperature and photosynthetic photon flux (PPF) regimes. Predictive models incorporating PPF, day temperature, and percentage leaf area expansion accounted for 78% and 81% of variation in net photosynthetic rate (Pn) before, and postattainment of, 75% maximum leaf area, respectively. Minimal changes in Pn occurred during the photoperiod when environmental conditions were stable. Maximum Pn (10.9μmol·m-2·s-1 or 13.3 μmol·g-1·s-1) occurred for plants grown under high PPF (694 μmol·m-2·s-1) and day temperature (28 °C). Acclimation of Pn was less than complete, with any gain through a greater light-saturated photosynthetic rate (Pmax) at high PPF also resulting in a reduction in quantum yield. Similarly, any gain in acclimation through increased quantum yield under low PPF occurred concurrently with reduced Pmax. It was concluded that Zantedeschia `Best Gold' is a shade tolerant selection, adapted to optimize photosynthetic rate under the climate of its natural habitat, by not having obligate adaptation to sun or shade habitats.
Genetic Analysis of the Raffinose Family Oligosaccharides in Common Bean
Authors: McPhee Kevin E. , Zemetra Robert S. , Brown Jack , Myers James R.
Published: January 2019

Common bean (Phaseolus vulgaris L.) is a nutritionally complete food, but contains antinutritional compounds that reduce digestibility. One group of compounds includes the raffinose family oligosaccharides (RFOs) (raffinose, stachyose, and verbascose), which are partly responsible for flatulence after beans are eaten. RFOs stabilize cell membranes during seed desiccation and when the seed rehydrates during germination. While low levels of RFOs are desirable nutritionally, high levels may enhance germination and emergence, particularly in cold, wet soils. Eight landraces selected for high and low sucrose, raffinose, and stachyose content, were crossed in a diallel mating design to investigate genetic control of the RFOs. Derivatized soluble sugars were measured using gas-liquid chromatography. Fructose, sucrose, raffinose, and stachyose were detected. In the F1, fructose varied from 0.1 to 2.5 mg·g-1 dry weight (DW), sucrose from 17.2 to 56.5 mg·g-1 DW, raffinose from 0.1 to 4.1 mg·g-1 DW, and stachyose ranged from 7.6 to 43.7 mg·g-1 DW. Griffing's analysis estimates of general combining ability were on average, 16.5 times larger than specific combining ability for all the RFOs, indicating that additive genetic variance was most important. Significant reciprocal differences were detected in the F1 and F2, but not in the F3. RFO accumulation was partially dominant as indicated by Hayman's analysis. Narrow sense heritability averaged over F2 and F3 generations for sucrose, raffinose, stachyose, total sugar, and total oligosaccharides were 0.22, 0.54, 0.44, 0.17, and 0.27, respectively. Moderate heritabilities indicate that manipulation of RFO accumulation in this set of bean lines would probably need to be done on a progeny row basis with replication.
T4 Lysozyme and Attacin Genes Enhance Resistance of Transgenic `Galaxy' Apple against Erwinia amylovora
Authors: Ko Kisung , Norelli John L. , Reynoird Jean-Paul , Aldwinckle Herb S. , Brown Susan K.
Published: January 2019

Genes encoding lysozyme (T4L) from T4 bacteriophage and attacin E (attE) from Hyalophora cecropia were used, either singly or in combination, to construct plant binary vectors, pLDB15, p35SAMVT4, and pPin2Att35SAMVT4, respectively, for Agrobacterium-mediated transformation of `Galaxy' apple, to enhance resistance to Erwinia amylovora. In these plasmids, the T4L gene was controlled by the cauliflower mosaic virus 35S promoter with duplicated upstream domain and the untranslated leader sequence of alfalfa mosaic virus RNA 4, and the attE gene was controlled by the potato proteinase inhibitor II (Pin2) promoter. All transgenic lines were screened by polymerase chain reaction (PCR) for T4L and attE genes, and a double-antibody sandwich enzyme-linked immunosorbent assay for neomycin phosphotransferase II. Amplification of T4L and attE genes was observed in reverse transcriptase-PCR, indicating that these genes were transcribed in all tested transgenic lines containing each gene. The attacin protein was detected in all attE transgenic lines. The expression of attE under the Pin2 promoter was constitutive but higher levels of expression were observed after mechanical wounding. Some T4L or attE transgenic lines had significant disease reduction compared to nontransgenic `Galaxy'. However, transgenic lines containing both attE and T4L genes were not significantly more resistant than nontransgenic `Galaxy', indicating that there was no in planta synergy between attE and T4L with respect to resistance to E. amylovora.
Enhanced Expression of BiP Is Associated with Treatments that Extend Storage Longevity of Primed Tomato Seeds
Authors: Gurusinghe Sunitha , Powell Ann L.T. , Bradford Kent J.
Published: January 2019

While seed priming (hydration in water or osmotic solutions followed by drying) enhances seed germination performance, the longevity of primed seeds in storage often is reduced. Postpriming treatments including a reduction in seed water content followed by incubation at 37 or 40 °C for 2 to 4 h can substantially restore potential longevity in tomato (Lycopersicon esculentum Mill.) seeds. These conditions might induce heat-shock proteins (hsp) that could be involved in the extension of seed longevity. The abundance of BiP (78 kD Binding Protein), hsp70 and class I small hsp in primed seeds subjected to postpriming treatments was examined to assess this possibility. BiP mRNA and protein amounts increased during postpriming heat treatments that extended longevity of tomato seeds. Treatment of primed seeds with the calcium ionophore calcimycin (A21387) enhanced BiP protein accumulation in the absence of heat treatment and also extended potential seed longevity. Changes in the abundance of hsp70 and class I small hsps were not consistently associated with potential seed longevity. Thus, enhanced BiP expression may contribute to the improved longevity of primed seeds following postpriming treatments.
Molecular Tagging of the Ms Locus in Onion
Authors: Gökçe Ali Fuat , McCallum John , Sato Yutaka , Havey Michael J.
Published: January 2019

Cytoplasmic-genic male sterility (CMS) is used to produce hybrid onion (Allium cepa L.) seed. For the most widely used source of onion CMS, male sterility is conditioned by the interaction of the male-sterile (S) cytoplasm and the homozygous recessive genotype at a nuclear male-fertility restoration locus (Ms). Maintainer lines are used to seed propagate male-sterile lines, possess normal (N) male-fertile cytoplasm, and are homozyous recessive at the Ms locus. Due to the biennial nature of onion, it takes 4 to 8 years of crossing and scoring of progeny phenotypes to establish if maintainer lines can be extracted from an uncharacterized population or family. Identification of nuclear markers tightly linked to the Ms locus would allow for molecular-facilitated selection of maintainer lines. We evaluated testcross progenies from a segregating family for nuclear restoration of male fertility over at least three environments. Although segregations in the F2 family fit the expected 1:2:1 ratio (P = 0.973), the proportion of male-sterile testcross progenies showed significant (P < 0.01) year effects and it is therefore imperative to score male-fertility restoration over environments. Too many male-sterile testcross progenies were often observed, indicating that the dominant allele conditioning male-fertility restoration for S cytoplasm may not show complete penetrance. Segregations of amplified fragment length polymorphisms and restriction fragment length polymorphisms (RFLPs) revealed RFLPs flanking the Ms locus at 0.9 and 8.6 cM. An onion cDNA showing highly significant homology to the aldehyde dehydrogenase conditioned by the rf2 locus of maize was identified and mapped to linkage group I, independent of the Ms locus. A sample of commercial onion germplasm was evaluated for putative allelic diversity at the RFLP loci linked to Ms. The genomic region corresponding to the cDNA (AOB272) revealing the closest RFLP to Ms was sequenced to reveal numerous single nucleotide polymorphisms. Single-stranded conformational polymorphisms and single nucleotide extensions were developed that revealed genomic variation at AOB272-EcoRI. The use of these molecular markers to select maintainer lines in onion is discussed.
Shoot and Cluster Thinning Influence Vegetative Growth, Fruit Yield, and Wine Quality of `Sauvignon blanc' Grapevines
Authors: Naor A. , Gal Y. , Bravdo B.
Published: January 2019

Effects of two shoot densities (14 and 44 shoots/vine) and two crop levels (one and two fruit clusters per shoot) on yield, pruning weight, crop load, and juice and wine quality of field-grown `Sauvignon blanc' grape (Vitis vinifera L.) were studied in a factorial experiment over 3 years. Main shoot length, lateral shoot length and number, shoot diameter, leaf area per shoot, and specific leaf weight were greater at the lower compared with the higher shoot density for all years whereas pruning weight was significantly increased only in the third year. Crop yield increased proportionally with the number of clusters, up to 44 clusters per vine, by both shoot and cluster thinning; a lower rate of yield increase was apparent when the number of clusters per vine was increased further, probably because of increasing source limitation. Berry maturation was delayed in the 44 shoots per vine treatment. Unchanged soluble solids, higher total acidity, and lower pH in the 44-shoot vine treatment in the third year indicated that the effect of cluster number on the must quality was not due to delayed maturation. No effect of cluster number per shoot on vegetative parameters was apparent. Berry size and number were affected by cluster thinning only in the 44 shoot/vine treatment. Both the number of shoots per vine and the number of clusters per shoot affected wine sensory attributes. Herbaceous aroma scores increased with increasing pruning weight. The wine sensory evaluation score decreased with increasing crop load. Total wine sensory scores decreased with decreasing leaf area to fruit weight ratio below ≈18 cm2·g-1, whereas a critical value of the crop to pruning weight ratio, for wine quality, was not apparent. Crop load expressed as crop to pruning weight ratio (kg·kg-1) was highly correlated with fruit weight to leaf area ratio (g·cm-2) (r2 = 0.86), providing a biological rationale for the relevance of crop load and wine quality relations.
Role of Gibberellins in Chrysanthemum Growth under Far Red Light-deficient Greenhouse Environments
Authors: Maki Sonja L. , Rajapakse Sriyani , Ballard Robert E. , Rajapakse Nihal C.
Published: January 2019

Plants grown in far red (FR) light deficient environments are typically shorter because of short internodes, resembling plants treated with GA biosynthesis inhibitors. The role of GAs in the reduction of stem elongation of `Bright Golden Anne' chrysanthemum [Dendranthem ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum ×morifolium Ramat.)] grown in FR light deficient (-FR) environment was investigated by following the response of chrysanthemums grown in - FR environment to exogenous application of GA1, GA19, or GA20, and the metabolism of GA12 and GA19 in -FR or +FR environment. FR light deficient environment resulted in 25% to 30% shorter plants than in +FR environment. Final height of GA1- and GA20-treated plants followed a quadratic pattern while that of GA19 treated plants followed a linear pattern as the dosage increased from 0 to 50 μg/apex. The response to GA1 was the greatest followed by GA20 and GA19, regardless of the light environment. Application of GA1 (50 μg/apex) increased final height by 65% compared with no GA (0 μg/apex) application under either +FR or -FR light environment, suggesting the response to GA1, which is the active form, remained the same. Responses to GA19 and GA20 declined under -FR light. [14 C]GA12 and [14C]GA19 metabolized slowly in the -FR environment suggesting that the turnover of GAs may have caused in part the lower response to GA19. Although metabolism of GA1 under -FR environments was not investigated, observations with GA1 application experiments support that -FR environment may have enhanced inactivation of GA1. Chemical name used: gibberellic acid (GA).
Effect of Apple Rootstocks on Average `Gala' Fruit Weight at Four Locations after Adjusting for Crop Load
Authors: Marini Richard P. , Barden John A. , Cline John A. , Perry Ronald L. , Robinson Terence
Published: January 2019

The influence of rootstock on average fruit weight was evaluated for a subset of data from a multilocation NC-140 apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] rootstock trial. Data for eight dwarf rootstocks were collected at four locations for 2 years. Analysis of covariance was used to evaluate the effect of rootstock on average fruit weight when crop density or number of fruit per tree was included in the linear model as a covariate. When number of fruit harvested per tree was used as a covariate, average fruit weight was not affected by rootstock in either year in Ontario. In Michigan and Virginia, rootstock and number of fruit per tree, but not the rootstock × number of fruit interaction, were significant, so common slopes models were used to estimate least squares means for average fruit weight. In general, trees on M.27 and P.1 produced the smallest fruit, and trees on B.9, M.9 EMLA, and Mac.39 produced the largest fruit. In New York the interaction of rootstock × number of fruit was significant, so least squares means were estimated at three levels of number of fruit per tree. Both years, at all levels of number of fruit, trees on M.26 EMLA produced the smallest fruit and trees on M.27 EMLA produced the largest fruit. Average fruit weight was most affected by number of fruit per tree when Mark was the rootstock. In general, results were similar when crop density was used as the covariate, except that trees on M.27 EMLA did not produce small fruit in Michigan and Ontario.
A Detached Leaf Technique for Studying Race-specific Resistance to Cladosporium caryigenum in Pecan
Authors: Conner Patrick J.
Published: January 2019

A detached leaf screening technique was developed for studying specific interactions between pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars and isolates of the pecan scab fungus, Cladosporium caryigenum. Monoconidial isolates were obtained from leaf scab lesions on `Wichita', `Desirable', `Cape Fear', and `Elliot'. Each isolate was then inoculated onto detached leaves of each of the four cultivars and fungal growth was observed under the microscope after eight days. `Wichita', `Desirable', and `Cape Fear' isolates produced subcuticular hyphae at a much higher frequency when inoculated back onto the cultivar from which they were isolated in comparison to the other cultivars. The `Elliot' isolate was able to produce a high frequency of subcuticular hyphae when inoculated onto `Elliot' and `Cape Fear', but not when inoculated onto `Desirable' and `Wichita'. Field inoculations conducted with the `Wichita' and `Desirable' isolates validated the detached leaf protocol. The results obtained indicate that pecan scab is composed of multiple races with a high degree of specificity for host cultivars. A rapid whole-leaf staining system is presented which appears to have wide applicability to assessing fungal growth in leaves.
Responses of `Bing' and `Rainier' Sweet Cherries to Ethylene and 1-Methylcyclopropene
Authors: Gong Yiping , Fan Xuetong , Mattheis James P.
Published: January 2019

`Bing' and `Rainier' sweet cherry (Prunus avium L.) fruit treated with 1-methylcyclopropene (1-MCP) were stored at 20 °C in air or 35 μL·L-1 ethylene. Ethylene production by both `Bing' and `Rainier' fruit stored in air was transiently stimulated following 1-MCP treatments, however, there were no significant effects of 1-MCP on respiration rate. Exogenous ethylene stimulated respiration regardless of prior treatment with 1-MCP. Although 1-MCP treatment reduced the increase in `Bing' respiration induced by ethylene, the reduction was less than reported previously for climacteric fruit. These results suggest that stimulation of sweet cherry fruit respiration by ethylene occurs via a process that may be independent of receptors to which 1-MCP binds. Postharvest changes in fruit color and development of stem browning were not altered by 1-MCP treatment, and exogenous ethylene accelerated the development of stem browning regardless of prior treatment with 1-MCP.
PCR-based Single-strand Conformation Polymorphism (SSCP) Analysis to Clone Nine Aquaporin Genes in Cucumber
Authors: Xie Jiahua , Wehner Todd C. , Conkling Mark A.
Published: January 2019

Combining the use of PCR and single-strand conformation polymorphisms (SSCP), nine sequences from the cucumber genome were successfully identified and cloned that encoded two well-conserved asparagine-proline-alanine (NPA) domain homologues to aquaporin genes. The sensitivity and detection efficiency of SSCP and restriction enzyme analysis for detecting DNA sequence variation were evaluated using similar-sized DNA fragments. The SSCP analysis was more sensitive and efficient for discriminating different clones than restriction enzyme analysis, although some sequence variation inside similar-sized DNA fragments could be identified by restriction analysis. Consideration of the results of SSCP analysis with DNA sequence information indicated that one or two base pair changes in the amplified regions could be detected. Moreover, the SSCP analysis results of genomic DNA PCR products that were amplified by degenerate primers can provide rough information about the number of member genes. If the SSCP bands of a cloned fragment (such as CRB7) did not have the corresponding bands from genomic DNA PCR products, that fragment might be a misamplified product. The PCR-based SSCP method with degenerate oligonucleotide primers should facilitate the cloning of member genes.
Combining Ability Analysis of Yield Components in Cucumber
Authors: López-Sesé Ana I. , Staub Jack
Published: January 2019

Three U.S.-adapted Cucumis sativus var. sativus L. lines and one C. sativus var. hardwickii (R.) Alef.-derived line were crossed in a half-diallel design to determine their combining ability for several yield-related traits (yield components). Six F1 progenies were evaluated in a randomized complete block design with eight replications in 1999 and 2000 for fruit number and length/diameter ratio (L:D), lateral branch number, number of female flowering nodes, and days to anthesis. Combining ability was significantly influenced (p < 0.05) by year for most of the horticultural traits examined. General combining ability (GCA) was significant for all traits in each year. Specific combining ability (SCA) was significant in magnitude and direction for only fruit number and days to anthesis. Data indicate that the C. sativus var. hardwickii-derived inbred line WI 5551 possessed SCA for yield component traits, and thus maybe useful for improving fruit yield in commercial cucumber.
Analysis of Apple Germplasm in Northwestern Spain
Authors: Pereira-Lorenzo Santiago , Ramos-Cabrer Ana M. , Ascasíbar-Errasti Javier , Piñeiro-Andión Juan
Published: January 2019

Spain is the 15th largest apple (Malus ×domestica Borkh.) producer in the world with production depending mainly on foreign cultivars. During the 1970s, a germplasm bank of local cultivars was established in Galicia with the aim of preserving the local resources of northwestern Spain. A total of 408 accessions were studied using 89 morphological characters, with 15 corresponding to phenology, 46 to fruit, 7 to flowers, 11 to leaves, 6 to pests and 4 to diseases. Three variable isoenzymes, PGM E.C.5.3.1.9, PGI E.C.2.7.5.1 and EST E.C.2.7.5.1, were analyzed for 405 accessions and 27 commercial cultivars. The main objectives of this work were 1) to evaluate the inter- and intracultivar variability using morphological characters and isoenzymes, 2) to classify the accessions according to the main sources of variability, and 3) to identify repetitions in the germplasm bank. Principal component analysis (PCA) revealed six main sources of variability in the following order: size of fruit, color of skin, acidity, sweetness, harvest time, and attractiveness. The PCA analysis across 350 accessions produced 42 morphological groups. The 3 isoenzymes produced 190 genotype clusters. Combining morphological classification with the isoenzyme genotypes, we found 31 groups of synonyms involving 82 accessions and 8 more possible groups involving 17 accessions. This result allows the elimination of 53 repetitive accessions from the germplasm bank. Six commercial cultivars were identified as the progenitors of eighteen accessions: `Reineta Blanca' of seven, `Reina de Reinetas' of two, `Reineta de Caux' of eight and `Golden Delicious', `Golden 4187' or `Ozark Gold' of one each. Because inter- and intracultivar variability was high and names given by the growers were not reliable, the suggested selection strategy is to select individual clones among and within cultivars to exploit both the inter- and intracultivar genetic variability.
Effects of 1-Methylcyclopropene and Heat Treatments on Ripening and Postharvest Decay in `Golden Delicious' Apples
Authors: Saftner Robert A. , Abbott Judith A. , Conway William S. , Barden Cynthia L.
Published: January 2019

Prestorage heat, CA storage, and pre- and poststorage treatments with the ethylene action inhibitor, 1-methylcyclopropene (MCP), were tested for their efficacy at inhibiting fungal decay and maintaining quality in `Golden Delicious' apples [Malus sylvestris (L.) Mill. Yellow Delicious Group] stored 0 to 5 months at 0 °C and 7 days at 20 °C. Before storage in air at 0 °C, preclimacteric fruit were treated with either MCP at a concentration of 1 μL·L-1 for 17 hours at 20 °C, 38 °C air for 4 days, MCP plus heat, or left untreated. Some sets of untreated fruit were stored in a controlled atmosphere of 1.5 kPa O2 and 2.5 kPa CO2 at 0 °C while other sets were removed from cold storage in air after 2.5 or 5 months, warmed to 20 °C, and treated with 1 μL·L-1 MCP for 17 hours. Prestorage MCP, heat, MCP plus heat treatments and CA storage decreased decay severity caused by wound-inoculated Penicillium expansum Link, Botrytis cinerea Pers.:Fr., and Colletotrichum acutatum Simmonds (teleomorph Glomerella acutata J.C. Guerber & J.C. Correll sp.nov.). Poststorage MCP treatment had no effect on decay severity. Both prestorage MCP treatment and CA storage delayed ripening as indicated by better retention of green peel color, titratable acidity, and Magness-Taylor flesh firmness, and the reduced respiration, ethylene production rates, and volatile levels that were observed upon transferring the fruit to 20 °C. The prestorage MCP treatment delayed ripening more than CA storage. Following 5 months cold storage, the prestorage MCP treatment maintained the shape of the compression force/deformation curve compared with that of fruit at harvest, as did CA storage, but at a lower force profile. The heat treatment had mixed effects on ripening: it hastened loss of green peel color and titratable acidity, but maintained firmness and delayed increases in respiration, ethylene production and volatile levels following cold storage. The MCP plus heat treatment inhibited ripening more than heat treatment alone but less than MCP treatment alone. In one of 2 years, the MCP plus heat treatment resulted in superficial injury to some of the fruit. Results indicated that MCP may provide an effective alternative to CA for reducing decay severity and maintaining quality during postharvest storage of `Golden Delicious' apples. Prestorage heat to control decay and maintain quality of apples needs further study, especially if used in combination with MCP.
Relationship between Flesh Firmness and Ground Color in Peach as Influenced by Light and Canopy Position
Authors: Lewallen Kara Senger , Marini Richard P.
Published: January 2019

The influence of photosynthetic photon flux (PPF) on peach [Prunus persica (L.) Batsch] fruit quality and the relationship between ground color and flesh firmness was studied by performing three experiments. Fruit with varying ground colors were sampled from different canopy positions with varying PPF. Fruit skin color was measured with a tristimulus colorimeter and values for L* (lightness), chroma (brightness), and hue angle (numerical values for color) were calculated for each fruit. Fruit from the canopy exterior generally were larger, had more surface area colored red, had higher soluble solids concentrations, and were darker, duller, and redder than fruit harvested from interior positions. In all three experiments, the relationship between hue angle and fruit firmness was affected by PPF, but the nature of the relationship (linear vs. curvilinear) and the influence of position was not consistent. When fruit were covered with aluminum foil or a section of the fruit surface was covered with duct tape to prevent light-induced red coloration of the skin, the relationship between hue angle and fruit firmness was similar for different canopy positions. Therefore, the relationship between ground color and fruit firmness is influenced by the light environment in which a fruit develops, and not by canopy position. Ground color does not seem to be a good indicator of fruit firmness because fruit with the same hue angle had greatly differing firmnesses.
Differentiation of Race Specific Resistance to Phytophthora Root Rot and Foliar Blight in Capsicum annuum
Authors: Oelke Lisa M. , Bosland Paul W. , Steiner Robert
Published: January 2019

Despite extensive breeding efforts, no pepper (Capsicum annuum L. var. annuum) cultivars with universal resistance to phytophthora root rot and foliar blight (Phytophthora capsici Leon) have been commercially released. A reason for this limitation may be that physiological races exist within P. capsici, the causal agent of phytophthora root rot and phytophthora foliar blight. Physiological races are classified by the pathogen's reactions to a set of cultivars (host differential). In this study, 18 varieties of peppers were inoculated with 10 isolates of P. capsici for phytophthora root rot, and four isolates of P. capsici for phytophthora foliar blight. The isolates originated from pepper plants growing in New Mexico, New Jersey, Italy, Korea, and Turkey. For phytophthora root rot, nine of the 10 isolates were identified as different physiological races. The four isolates used in the phytophthora foliar blight study were all determined to be different races. The identification of physiological races within P. capsici has significant implication in breeding for phytophthora root rot and phytophthora foliar blight resistance.
Orchard Floor and Nitrogen Management Influences Soil and Water Quality and Tart Cherry Yields
Authors: Sanchez Jose E. , Edson Charles E. , Bird George W. , Whalon Mark E. , Willson Thomas C. , Harwood Richard R. , Kizilkaya Kadir , Nugent James E. , Klein William , Middleton Alan , Loudon Theodore L. , Mutch Dale R. , Scrimger Joseph
Published: January 2019

Designing and implementing more productive, nutrient-efficient, and environmentally sound orchard management systems requires a better understanding of plant and soil responses to more biologically driven management practices. This study explored the effect of orchard floor and N management on soil organic C and N, populations of nematodes, NO3 leaching, and yields in tart cherry (Prunus cerasus L. `Montmorency') production. A baseline conventional orchard system consisting of an herbicide-treated tree row and a full rate of N fertilizer was compared to two modified-conventional and ten alternative orchard floor and N management systems. Living ground cover and the use of mulch with or without composted manure increased total C and the active C and N pools in the soil. For instance, supplemental mulch or mulch applied using a side-delivery mower increased soil C by >20% above the conventional baseline. The size of the active C pool increased 45% and 60% with the use of the species mix 2 ground cover and compost, respectively. Increases in the active N pool ranged from a low of 25% in the soils using mulch or a ground cover mix to a high of 60% when compost was used. As a result, the ability of these soils to provide N to growing plants was enhanced. Total soil N increased in the treatment using natural weeds as ground cover and the full rate of N fertilizer. It is likely that weeds were able to convert significant amounts of fertilizer N into organic forms. Increasing the active C and N pools stimulates microbial activity, and may favor populations of nonplant parasitic nematodes over plant parasitic species. Using a trunk-to-trunk cover crop mix under the cherry trees reduced NO3 leaching by >90% compared to a conventional, herbicide treated soil, even when N fertilizer was used at full rate. Nitrate leaching also dramatically diminished when N fertilizer was fertigated at a reduced rate or when compost was used as N source. Alternative orchard floor and N management did not reduce yields when compared to the baseline conventional treatment.
An Integrated Microstructural and Sensory Approach to De scribe Apple Texture
Authors: Allan-Wojtas P. , Sanford K.A. , McRae K.B. , Carbyn S.
Published: January 2019

The apple industry worldwide would benefit from an improved and standardized description of fresh-apple textural quality. The description proposed here is unique in that it integrates structural, sensory, and consumer information. To demonstrate its benefits, 24 apple cultivars [Malus ×sylvestris (L.) Mill. var. domestica (Borkh..) Mansf.] were sampled over two harvest seasons and analyzed using microstructural and sensory techniques. Cultivars were selected to cover a range of known sensory textures, and microstructural profiles were compiled in parallel with sensory and instrumental studies. Each cultivar was pre pared for conventional scanning electron microscopy (SEM) observation using standard methods. Representative fruit from each cultivar were photographed at three magnifications to visualize fruit architecture, tissue relationships, and size, shape, and arrangement of cells within layers to compile the microstructural profile. A trained sensory panel evaluated the cultivars for crispness, surface coarseness, sponginess, hardness, juiciness, degree of melting, mealiness, and skin toughness while a consumer panel rated liking. This information was compiled into a texture profile. The microstructural and texture profiles were then combined into a cultivar profile for each sample. Cultivar profiles were collected to form a database; subtle similarities and differences among the 28 market-quality samples were interpreted and noted. With this technique, those structures with similar sensory properties can be identified with some form of microscopy. Clarifying and predicting the parameters that are related to textural quality in new cultivars will streamline the introduction process.
Quality Determination of Red Radish by Nondestructive Root Color Measurement
Authors: Schreiner Monika , Krumbein Angelika , Schonhof Ilona , Widell Stefanie , Huyskens-Keil Susanne
Published: January 2019

A new approach for nondestructive quality assessment based on color measurement was developed for red radishes (Raphanus sativus L.). Postharvest changes in hue angle corresponded with changes in soluble and insoluble pectic substances linked to textural characteristics in `Nevadar' radishes. Changes in glucosinolates were related to changes in chroma and were associated with radish flavor. However, monosaccharides were not related to root color during the 4 days of postharvest period. Nevertheless, the data suggest that root color may be used as a rapid, inexpensive and reliable indicator of quality during the postharvest distribution of radish.
Peach Tree Response to Single and Combined Regulated Deficit Irrigation Regimes under Shallow Soils
Authors: Girona Joan , Mata Mercè , Arbonès Amadeu , Alegre Simó , Rufat Josep , Marsal Jordi
Published: January 2019

Productive and vegetative tree responses were analyzed during 3 consecutive years in peach [Prunus persica (L.) Batsch cv. Sudanell] plots subjected to three regulated deficit irrigation (RDI) strategies plus a control irrigation treatment. A postharvest RDI treatment (RDI-P) was irrigated at 0.35 of control after harvest. A Stage II RDI treatment (RDI-SII) was irrigated at 0.5 of control during the lag phase of the fruit growth curve. The third treatment (RDI-SII-P) applied RDI during Stage II at 0.5 of control and postharvest at 0.35 of control. The control treatment, like RDI-P and RDI-SII-P when not receiving RDI, was irrigated at 100% of a water budget irrigation scheduling in 1994 and 1996, full crop years, and 80% of the budget in 1995, an off year with a very small crop. A carry-over effect of deficit irrigation was highly significant in all parameters measured during the third year of the experiment. The general effect of water stress during Stage II did not affect return bloom and fruit set, whereas water stress during postharvest apparently reduced both parameters. As a consequence, fruit counts and fruit load manifested marked differences between treatments, which were also correlated to changes in fruit size. The RDI-II, which had the highest fruit yield, also had the smallest fruit size, whereas RDI-P manifested the lowest yield and largest fruit size. Vegetative growth (shoot elongation and trunk cross sectional area) was significantly reduced during the first 2 years of the experiment in accordance with the amount of the irrigation reduction. However, in 1996 growth was strongly governed by fruit load. The use of RDI-SII-P represented an intermediate cropping effect between the opposite bearing behavior of RDI-SII and RDI-P, while not expecting distinctive fruit yield or size reductions and offering remarkable water savings of 22% of the control applied water.