bluuebunny/crossref_metadata_2025 huggingface dataset:
Response to Selection and Associated Changes in Genetic Variance for Soluble Solids and Titratable Acids Contents in Strawberries
Authors: Shaw Douglas V.
Published: January 2019

Parental potential, or breeding value, was evaluated for strawberry (Fragaria × ananassa Duch.) genotypes selected for high, intermediate, or low phenotypic expression of soluble solids content (SSC) and titratable acid content (TA). Progeny means and genetic variance parameters were estimated using seedlings from 40 crosses among these selections, conducted in two factorial sets. Selection response for breeding value was detected for SSC in the upward direction and for TA in both upward and downward directions. Populations created by divergent selection of parents followed by intermating expressed additive genetic variances 2.3 and 9.3 times larger than those estimated for appropriate controls for SSC and TA, respectively. For TA, the response to selection for breeding value was consistent with results for genotypic selection reported earlier. The significant selection response in breeding value obtained for SSC differed from the results of previous clonal tests that had detected no significant genotypic selection response. These results, together with previous assessments, suggest that cumulative genetic gain can be obtained for both SSC and TA. However, gain for SSC will be contingent on selection under conditions that approximate commercial treatment; this will not be necessary for TA, as expression for this trait is stable across test location and cultural treatments.
Somatic Embryogenesis in Three Magnolia Species
Authors: Merkle S.A. , Wiecko A.T.
Published: January 2019

Cultures were initiated from immature seeds of three species of magnolia: sweetbay magnolia (Magnolia virginiana L.), fraser magnolia (M. fraseri Walt.) and yellow cucumbertree [M. acuminata var. cordata (Michx.) Sarg.]. Immature seeds were bisected longitudinally and cultured on a solidified conditioning medium containing 2 mg 2,4-D/liter, 0.25 mg BA/liter, 40 g sucrose/liter, and 1 g casein hydrolysate/liter. Cultures were maintained in the dark at 22C and transferred to fresh medium at monthly intervals. Within 2 months of culture, somatic embryos or proembryogenic masses proliferated from one end of the endosperm mass. Somatic embryos and proembryogenic masses of each species were cultured on a hormone-free version of the conditioning medium to complete maturation and then transferred to the same hormone-free medium, minus casein hydrolysate, to initiate germination. Germinants were transferred to a hormone-free plantlet development medium for conversion. Plantlets of all three species survived transfer to soil mix and continued to grow. Chemical names used: (2,4 -dichlorophenoxy) acetic acid (2,4-D), N- (phenylmethyl)-1H-purin-6-amine (BA).
Comparisons of Temperature Measurements from Local Weather Stations and the Tomato Plant Canopy: Implications for Crop and Pest Forecasting
Authors: Davidson Nita A. , Wilson L. Theodore , Hoffmann Michael P. , Zalom Frank G.
Published: January 2019

Temperatures recorded by weather stations and within the canopy of tomato (Lycopersicon esculentum Mill.) crops were compared in fields near Davis, Calif., during Summer 1983 (60 days) and 1987 (50 days). For both years, the average maximum and minimum temperatures, daily temperature ranges, degree days per day, and total accumulated degree days were compared. In 1983, the mean maximum temperature at the weather station did not differ significantly from that in the canopy, but the mean minimum temperature at the weather station was significantly lower than that in the canopy. In 1987, the mean maximum temperature at the weather station was significantly higher than that in the canopy, but mean minimum temperatures did not differ significantly. Temperature ranges were significantly narrower for the weather station toward the end of the 1983 season, and significantly wider for the weather station at midseason 1987. Comparisons of degree days per day showed significant differences between means at the weather station and in the canopy in 1983, and among those at the weather station and the two degree day calculation methods used for temperatures recorded in the canopy. Total accumulated degree days based on temperature records at the weather station were lower than those in the canopy in 1983 but higher in 1987. In 1987, the single sine degree day calculation method overestimated degree days compared to the 2-hr triangulation method. The phenology of the tomato crop as predicted by weather station temperatures indicated that tomato maturation was underestimated in 1983 and overestimated in 1987. The rate of development for hypothetical populations of Heliothis zea (Boddie) and Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) within the tomato crop was again underestimated in 1983 and overestimated in 1987, as based on temperature data of the weather station.
14Carbon-labeled Photosynthate Partitioning in Ilex crenata `Rotundifolia' at Supraoptimal Root-zone Temperatures
Authors: Ruter John M. , Ingram Dewayne L.
Published: January 2019

Ilex crenata Thunb. `Rotundifolia' split-root plants were grown for 3 weeks with root zones at 30/30, 30/34, 30/38, 30/42, 34/34, 38/38, and 42/42C. The 38C root-zone treatment was the upper threshold for several growth and physiological characteristics. A portion of the root system grown at or near the optimum temperature could compensate, in terms of shoot growth, for part of the root system exposed to supraoptimal root-zone temperatures up to 38C. Higher root-zone temperatures did not affect short-term photosynthetic rates or root : shoot ratios, but altered photosynthate partitioning to various stem and root sinks. Although no differences were found for total 14C partitioned to the roots, partitioning of 14C into soluble and insoluble fractions and the magnitude of root respiration and exudation were influenced by treatment. Heating half of a root system at 38C increased the amount of 14C respired from the heated side and increased the total CO2respired from the nonheated (30C) half. Exposure of both root halves to 42C resulted in membrane damage that increased the loss of 14C-labeled photosynthates through leakage into the medium.
Flower Colors in Common Bean Produced by Interactions of the Sal and V Loci and a Gametophyte Factor Ga Linked to Sal
Authors: Bassett Mark J. , Lin-Bao Xue , Hannah L. Curtis
Published: January 2019

Inheritance of red flower color was investigated in crosses using Lamprecht's lines M0169 and M0056, which are derived from Phaseolus coccineus L., and Univ. of Florida P. vulgaris L. breeding line 5-593. Based on segregation in the F2populations from 5-593 × M0169 and 5-593 × M0056, we hypothesize that the genotypes for flower colors are sal/sal V/V for 5-593 and Sal/Sal v/v for M0169 and M0056. The backcross 5-593 × F, (5-593 × M0056) segregated for four flower colors in about equal frequencies, and F2, F3, and F4progeny tests of the backcross plants provided confirmation of all the genotypes in the digenic model. The two recombinant true-breeding colors/genotypes were white (sal/sal v/v) and china rose (Sal/Sal V/V). We hypothesize that the large deficiency of plants carrying the Sal allele in segregating populations is due to a gametophyte factor linked to Sal. We propose the gene symbol Ga for the gametophyte factor locus, which achieves complete selection for pollen carrying Ga on female plants carrying Ga, i.e., no pollen carrying ga achieves fertilization. The linkage between Ga and the marker locus Sal is 17 CM (centiMorgan).
Fruit Growth and Development of `Ideal' and `Western' Pecans
Authors: Herrera Esteban A.
Published: January 2019

Pecan [Carya illinoensis (Wangenh.) K. Koch] fruit development was evaluated over three growing seasons (1981-83) to determine the seasonal growth patterns in the cultivars Ideal and Western. Gross morphological stages were examined weekly in fruit dissected in cross and longitudinal sections. Free-nucleate endosperm was first observed in mid-July when fruit had grown to 50% of their final length, occurring at 67 days after stigma receptivity (DASR) for `Ideal' and 76 DASR for Western'. Maximum content of free-nucleate endosperm occurred 100 DASR in `Ideal' and 109 DASR in Western' fruit. Ovary wall Signification was completed 119 DASR in `Ideal' and 132 DASR in `Western'. At this time, nut enlargement was complete. Cotyledon thickening required 36 and 43 days for `Ideal' and Western', respectively. The time from stigma receptivity to completion of cotyledon thickening in mid-October was 13 days longer for Western' than for `Ideal'. Because of a cool spring in 1983, all stages required a longer time in 1983 than in the previous 2 years. Most aspects of fruit development were similar between `Ideal' and Western' over the 3-year study.
Calcium-mediated Postharvest Changes in Texture and Cell Wall Structure and Composition in `Golden Delicious' Apples
Authors: Glenn Gregory M. , Poovaiah B.W.
Published: January 2019

Changes in texture, cell wall structure and composition during storage of Ca-treated and untreated `Golden Delicious' apple fruit (Malus domestics Borkh.) were investigated. The cell wall region of Ca-treated fruit showed no swelling during storage and cell-to-cell contact was maintained, whereas regions of the middle lamella in untreated tissue stained lightly, appeared distended, and eventually separated. In control fruit, microfibril orientation was lost in distended regions of the cell wall, especially in the outer wall region adjacent to the middle lamella. Furthermore, the middle lamella was fenestrated and in some cases was completely degraded. These changes during storage of control fruit were accompanied by a decrease in arabinose and galactose moieties of the cell wall and an increase in soluble pectin. Calcium treatment of fruit inhibited solubilization of polyuronide and arabinose moieties and reduced the loss in galactose content during storage. Tensile strength and firmness were positively correlated to Ca content of the fruit cortex. Excessive tensile stress caused tissue failure in control fruit when cells of the cortical tissue separated at the middle lamella. In contrast, cylinders of Ca-treated fruit fractured through cortical cell walls.
Mineral Analysis from Corkspotted and Normal `Anjou' Pear Fruit
Authors: Curtis Dan , Righetti T.L. , Mielke Eugene , Facteau Tim
Published: January 2019

Relationships between mineral content and corkspot in `Anjou' pears (Pyrus communis) were evaluated in 1985 and 1986. Although there were no significant relationships between mean preharvest fruit mineraI content and corkspot incidence, the postharvest mineral concentrations of corkspotted and normal fruit were markedly different. Corkspotted and normal pear fruit had different Ca and N : Ca ratios in all types of subsamples (peels, opposing tangential slices with peels, opposing tangential slices without peels, cortical tissue plugs from the area next to the core, cortical tissue plugs from the area just inside of the peel, and the cores including seed), based on either dry or fresh weight. The dry-weight basis also revealed differences in Mg concentrations in both years and in B and K concentrations in 1986. Peel concentrations correlated with other tissues and were the easiest subsample to process. Corkspot was absent in either year, with a peel N: Ca ratio below 6.3. A computer model used mean Ca concentrations and standard deviations to estimate the percentage of pears in each orchard that were less than a given threshold level. When the overall average percentage of arbitrarily defined low-Ca pears was small (< 10%), it was difficult to predict the actual number of low-Ca pears from mean Ca concentrations. Therefore, it may not be realistic to expect strong correlations between mean Ca concentration and the incidence of disorders commonly encountered in Hood River, Ore. This situation occurred even when Ca concentrations of disordered and normal pears clearly differed.
Endogenous Abscisic Acid Concentrations, Vegetative Growth, and Water Relations of Apple Seedlings following PEG-induced Water Stress
Authors: Robinson Terence L. , Barritt Bruce H.
Published: January 2019

In unstressed apple seedlings (Malus domestics Borkh.), concentrations of free abscisic acid (ABA) decreased in order from apical stem sections, immature expanding leaves, mature stem sections, and mature leaves. PEG-induced water stress stimulated a 2- to 10-fold increase in free ABA concentrations 1 day after treatment, depending on the amount of stress and the tissue. By the 3rd day of stress, free ABA concentrations were nearly the same as the unstressed treatment and remained low for the remainder of the 21-day stress period. Bound ABA concentrations were an order of magnitude lower than free ABA and were not influenced dramatically by water stress. Shoot growth rate, leaf expansion rate, and leaf emergence rate were reduced by water stress in relation to the severity of the stress; this reduction was associated with the initial increase in ABA. However, there was no increase in shoot or leaf growth rates associated with the decline in ABA concentrations by day 3 as growth rates remained depressed on water-stressed plants throughout the 21-day stress period. Water stress reduced evapotranspiration rate and midshoot leaf water potential (ψW)after 1 day, but leaf osmotic potential (ψS) adjusted more slowly, resulting in a loss of leaf turgor. The reduction in leaf turgor pressure (ψP) was highly correlated with decreased shoot growth rate and increased ABA concentrations on day 1 after treatment. By the 3rd day of water stress, ψP bad recovered even in the most severe treatment, and the recovery of turgor was associated with the drop in ABA concentrations. However, the increase in midshoot ψP and the decline in ABA were not associated with any increase in shoot growth rate. The continued inhibition of shoot growth was probably not related to ABA or turgor pressure of mature leaves but may have been related to turgor pressure in the growing tip.
Rate and Uniformity of Herbaceous Perennial Seed Germination and Emergence as Affected by Priming
Authors: Samfield Dina Margaret , Zajicek Jayne M. , Cobb B. Greg
Published: January 2019

Seeds of tickseed (Coreopsis lanceolata L.) and purple coneflower [Echinacea purpurea (L.) Moench] were primed in aerated solutions of distilled water or 50 or 100 mM salt (potassium phosphate, pH 7.0) at 16C for 3, 6, 9, or 12 days. Coreopsis seeds primed in the 50 mM buffer germinated the most rapidly and uniformly, and, under stress conditions in the greenhouse, resulted in a faster-growing, more-uniform crop than other treatments. Seeds primed in distilled water and the 50 mM buffer germinated faster and at higher rates at suboptimal temperatures in the laboratory than nonprimed seeds. Priming of Echinacea purpurea seeds for 6 or 9 days in distilled water or in the 50 mM buffer resulted in faster, more-uniform germination than other treatments. Seedling emergence under stress conditions was improved by all priming regimes, with best emergence occurring in treatments that lasted > 3 days. Priming also increased germination rates of E. purpurea at suboptimal temperatures in the laboratory.
Heritability and Correlation of Biomass, Growth Rates, Harvest Index, and Phenology to the Yield of Common Beans
Authors: Scully B.T. , Wallace D.H. , Viands D.R.
Published: January 2019

One-hundred-twelve common bean (Phaseolus vulgaris L.) lines of diverse origin were grown in three environments in 1986 and two environments in 1987. The purpose was to estimate broad-sense heritabilities of nine yield-related traits and the phenotypic, genetic, and environmental correlations among them. The traits and their heritabilities were seed yield (0.90), biomass (0.93), harvest index (0.92), days to maturity (0.96), days to flower (0.98), days of pod fill (0.94), biomass growth rate (biomass/days to maturity) (0.87), seed growth rate (seed yield/days of pod fill) (0.87), and economic growth rate (seed yield/days to maturity) (0.86). These high heritabilities were attributed to the broad genetic diversity and the comparatively small variances associated with the genotype × environment interactions. Genetic correlations of yield were: with biomass, 0.86; harvest index, 0.42; days to maturity, 0.40; days to flower, 0.33; days of pod fill, 0.24; biomass growth rate, 0.92; seed growth rate, 0.84; and the economic growth rate, 0.85. The concomitant phenotypic correlations were mostly equal to the genetic correlations for biomass and the three growth rates, but lower for the phonological traits (days to maturity, flower, and pod fill). Harvest index had the lowest correlations with yield. Correlations were also reported for the other 28 pairwise combinations among these nine traits. Indirect selection was explored with yield as the primary trait and the other eight as secondary traits. Estimates of relative selection efficiency (p) suggested that indirect selection was not a viable option for increasing common bean yields or identifying superior parents.
A New Genotype for White Seed Coat Discovered in `Early Wax' Snap Bean
Authors: Bassett Mark J. , Blom Arie
Published: January 2019

The white-seeded snap bean `Early Wax' (Phaseolus vulgaris L.) was crossed with a black-seeded breeding line 5-593. The F2 segregation data are consistent with a three-gene model, in which all three genes must be homozygous recessive to give white seed coat. One of the genes is t because of segregation in F2 for plants with white flowers and partial seed coat coloration. We hypothesize that the genes ers and ers2 in the presence of f block all seed color expression in all genes for partial coloration of seed. The hypothesis of three recessive genes was confirmed in a backcross test involving `Early Wax' x F1. The interaction of ers and ers2 was tested in progeny tests of partly colored BC-F1 plants. One of the erasure genes, ers2, blocks color expression in color zones close to the hilum, but only in the presence of ers. The other erasure gene, ers, blocks color expression only in color zones beyond those close to the hilum in a manner similar to the restr locus of Prakken (1972). The old hypothesis that partly colored seed phenotypes require the presence of a second factor e in addition to t, where the function of e is vague and unspecified, should be discarded for lack of supporting evidence, Under the new hypothesis, soldier series phenotypes (e.g., bipunctata, arcus, virgata, and virgarcus) may express in t ers Ers2 by action of ers or in t Ers Ers2 by action of various genes for partly colored seeds other than ers.
Quantification of Temperature Effects on Stem Elongation in Poinsettia
Authors: Berghage Robert D. , Heins Royal D.
Published: January 2019

Elongation characteristics of each internode on a lateral shoot of poinsettia (Euphorbia pulcherrima Klotz) `Annette Hegg Dark Red' were determined from pinching through anthesis for plants grown with 36 day/night temperature (DT/NT) combinations between 16 and 30C. The Richards function was used to describe the elongation of each internode. The first internode developing on a lateral shoot was longer and matured faster than subsequent internodes. The length of the first internode was a function of the difference between day and night temperatures (DIF = DT - NT). Subsequent internodes elongated uniformly in the absence of flower initiation. In the absence of flower initiation, the length of an internode, after the first, was a function of DIF. Internodes were shorter as proximity to the inflorescence increased. Internode length after the start of short days was a function of DIF and the visible bud index where visible bud index = [(days from pinching to the day an internode began to elongate - days from pinching to the day of the start of flower initiation)/the number of days from pinching to visible bud]. A poinsettia lateral shoot elongation model was developed based on the derived functions for internode elongation. The model predicted lateral shoot length within one standard deviation of the mean for plants grown in a separate validation study with 16 combinations of DT/NT. The model allows the prediction of lateral shoot length on any day from pinching through anthesis based on temperature, the number of nodes on the lateral shoot, the time each internode on the lateral shoot began elongating, and the visible bud index at the start of elongation of each node.
Micro- and Cutting Propagation of Silver Maple. II. Genotype and Provenance Affect Performance
Authors: Preece John E. , Huetteman Carl A. , Ashby W. Clark , Roth Paul L.
Published: January 2019

During 1987, we selected the six fastest-growing seedlings or clones from each of 15 provenances that represented the natural distribution range of silver maple (Acer saccharinum L.). Shoots from all 90 trees were cut into nodal segments, rooted as cuttings, and maintained as clonal stock plants in the greenhouse. Rooting was generally excellent and more than half of the clones rooted ≥90%. At the same time, explants were obtained from these field-grown trees and many were established in vitro as aseptic cultures by first pretreating with benomyl and rifampicin. Single-node explants from the greenhouse-grown clonal stock plants were also established and multiplied in vitro. There was a significant effect of clone within provenance on all in vitro growth characteristics. All clones proliferated axillary shoots, but not all at the same rates. Although statistically significant, low correlation coefficients indicated that micropropagation results were not good predictors of nursery performance of the populations from which the clones were selected, nor of the climatic conditions at the site of origin of the trees. The micropropagation system reported herein, therefore, should be applicable to a wide variety of silver maple genotypes. Chemical name used: methyl [1-[butylamino)carbonyl]-1H-benzimidazol-2-yl]carbamate(benomyl).
Cold Hardiness of Various Provenances of Flame, Roseshell, and Swamp Azaleas
Authors: Pellett Norman E. , Rowan Nancy , Aleong John
Published: January 2019

Florets of eight provenances representing three native North American azalea species [Rhododendron calendulaceum (Michx.) Torr., R. prinophyllum (Small) Millais, and R. viscosum (L.) Torr.] being grown in Burlington, Vt., were compared during three seasons for cold hardiness by laboratory freezing during cold acclimation. There was a large variability in the number of florets killed within an inflorescence in response to freezing temperatures. Cold hardiness of florets of the three species ranked, from most to least hardy, were R. viscosum, R. prinophyllum, and R. calendulaceum. Some differences were noted in cold hardiness of florets of provenances, but these were not necessarily related to latitude or elevation of origin. Cold hardiness of most provenances showed a significant linear relationship with the daily mean temperature of the 3 days preceding freezing tests. Ambient temperatures just before subfreezing test temperatures may affect winter injury more than provenance differences for these species.
The Role of Temperature and Photoperiod on Liatris spicata Shoot Development
Authors: Espinosa Ignacio , Healy Will , Roh Mark
Published: January 2019

Shoot emergence of cold-treated Liatris spicata Willd. corms was inhibited by SC soil, delayed at 10 or 15C (7 and 5 days, respectively), and promoted at 20, 25, or 30C. Within 15 days after planting, soil at 20C promoted the highest percentage of shoot emergence (81%). Plants were grown during the first 35 days after emergence under a combination of temperature and long or short days. Flowering shoot length was increased by either short days (8 hours; SD) at 13 or 15C or a 4-hour incandescent night interruption (NI) at 18C. When planted in May, a NI at 15 or 18C decreased the time to harvest by up to 14 days, whereas in November increasing the temperature to 18C, regardless of photoperiod, decreased the days to harvest by 16 days. Plants grown during the first 35 days after emergence under natural days at 15C then placed at 13, 15, or 18C under NI until harvest did not respond to the increasing temperature. Temperature and photoperiod influence Liatris development primarily during the first 35 days of development.
Pecan Cultivar Susceptibility to Sooty Mold Related to Leaf Surface Morphology
Authors: Sparks Darrell , Yates I.E.
Published: January 2019

Sooty mold washed from leaves of four cultivars of pecan [Carya illinoensis (Wangenh.) C. Koch] was quantified. The amounts of sooty mold accumulation differed significantly (P ≤ 0.05) among the cultivars. Leaf surface morphology of each cultivar was examined. A higher incidence of sooty mold was associated with cultivars having a rough, granulated leaf topography than those with smoother leaf surfaces. Characteristics of leaf surface morphology may be useful in selecting germplasms with reduced susceptibility to sooty mold accumulation.
Starch and Sugar Accumulation in Two Accessions of Lycopersicon cheesmanii
Authors: Garvey T. Casey , Hewitt John D.
Published: January 2019

A study using Lycopersicon cheesmanii Riley LA 1449 (typicum), a low soluble solids content (SSC) accession, and L. cheesmanii f. minor LA 528 (minor), a high SSC accession, was undertaken to characterize the accumulation of starch, sugar, and total SSC. Fruit of each accession was sampled throughout development to identify differences in SSC, starch accumulation, and sugar distribution. Osmetric analysis indicated that the minor race had higher SSC content throughout the ontogeny of fruit development than the typicum. Typicum contained more starch than minor, and both accessions showed a rapid decline in percent starch as the fruit ripened. Sucrose remained low throughout all stages of fruit development for both accessions. Glucose increased in the minor and declined in the typicum. Fructose increased in both accessions. Total reducing sugar content at the full ripe stage was higher in minor than the typicum.
Force to Shear the Stalk, Stalk Diameter, and Yield of Broccoli in Response to Nitrogen Fertilization and Within-row Spacing
Authors: Kahn Brian A. , Shilling Phillip G. , Brusewitz Gerald H. , McNew Ronald W.
Published: January 2019

Broccoli [Brassica oleracea L. (Italica Group)] crops may be rejected by wholesale buyers due to unacceptably tough stalks. Four experiments were conducted to examine the effects of various N levels and two within-row spacings (15 and 30 cm) on force to shear the stalk, stalk diameter, and yield of transplanted `Premium Crop' broccoli. Shear was not affected by within-row spacing, and average stalk diameter was decreased only 3 mm by reducing spacing from 30 to 15 cm. Although the 15-cm spacing sometimes produced the greatest total number of marketable, heads, this spacing resulted in higher cull head production, lower average marketable head weight, delayed maturity, and a lower percentage of field-planted transplants producing marketable heads than the 30-cm spacing. Increasing N fertilization decreased force to shear the stalk in only one experiment, when plants were exposed to water deficits and high temperatures. Nitrogen affected stalk diameter only when very low rates (37 and 74 kg·ha-1) were included. Yield of marketable-quality heads often showed no significant response to rates of applied N >112 kg·ha-1, particularly at the 30-cm spacing. Hollow stem was negligible in all experiments.
A Study of Triploid Tomato Fruit Attributes
Authors: Kagan-Zur V. , Yaron-Miron D. , Mizrahi Y.
Published: January 2019

A spontaneous tomato (Lycopersicon esculentum Mill.) triploid was studied with a view to its commercialization. Fruits induced by auxin contained 50% more DNA and 30% more protein than their diploid counterpart. The fruits were 50% larger than those of the diploid counterpart and were juicy but seedless. All fruit quality characteristics checked (polygalacturonase activity, reducing sugars content, electrical conductivity, pH, titratable acidity, pigment content, and shelf life) were comparable to the diploid except for ethylene evolution rate, which was lower than that of the diploid counterpart, and flavor, which was superior. The line seems suitable for agricultural cultivation.
Soil Management Affects Shoot and Root Growth, Nutrient Availability, and Water Uptake of Young Peach Trees
Authors: Glenn D.M. , Welker W.V.
Published: January 2019

We determined how differences in peach tree water use and shoot and root growth due to ground cover treatments are affected by tree response and soil conditions in the adjacent soil environment. Ground cover combinations of bare soil (BS), a killed K-31 tall fescue sod (KS), a living Poa trivialis sod (PT), and a living K-31 tall fescue sod (LS) were imposed on 50% of the soil surface in greenhouse studies. The ground cover on 50% of the soil surface influenced root and top growth of the peach trees [Prunus persica (L) Batsch], water use, and NO3-N levels in the opposing 50%, depending on the competitiveness of the cover crop (LS vs. PT and KS) and characteristics of the soil (BS vs. KS). Tree growth was allometrically related to root growth.
Developmental Light Environment and Net Gas Exchange of Cocoyam (Xanthosoma sagittifolium)
Authors: Valenzuela Hector R. , O'Hair Stephen K. , Schaffer Bruce
Published: January 2019

The effects of shade during leaf development on photosynthetic activity of cocoyam [Xanthosoma sagittifolium (L.) Schott] were investigated. Net gas exchange and N and chlorophyll concentrations were determined for cocoyam leaves growing in 30%, 50%, or 100% sunlight. Net CO2 assimilation (A) and water use efficiency (WUE) were greater for plants grown in 100% sunlight than for plants grown in less sunlight. Substomatal CO2 concentration increased with increased shading. Stomatal conductance (gs) and transpiration (E) did not vary significantly among treatments. Diurnal paterns for A were positively correlated with gs, lamina temperature, relative humidity, and photosynthetic photon flux (PPF). Lamina N concentrations, determined on lamina dry weight and lamina area bases, increased with increased PPF. Shade plants (30% and 50% sunlight) had greater chlorophyll: N ratios (dry-weight basis) and greater lamina area: lamina dry weight ratios than 100% sunlight-grown plants, which indicates increased photosynthate and N allocation to leaves of shade plants and maximization of light interception.
Development of a Seedling-applied Antitranspirant Formulation to Enhance Water Status, Growth, and Yield of Transplanted Bell Pepper
Authors: Nitzsche Peter , Berkowitz' Gerald A. , Rabin Jack
Published: January 2019

The objective of this research was to develop an effective antitranspirant formulation for reducing transplant shock (transitory water stress) in bell pepper (Capsicm annuum L.) seedlings. A formulation with a paraffin wax emulsion (Folicote at 5%) and a spreader/sticker type surfactant (Biofilm at 0.5%) was effective as an antitranspirant. This formulation was less phytotoxic than other formulations tested. Application of the formulation led to increased leaf water potential (Ψ w) i in transplanted seedlings for several days as compared with untreated transplants. When this, (relatively) nonphytotoxic formulation was used in a field study for 1 year, increased seedling Ψ w during a period of imposed water stress led to less leaf abscission and increased plant growth throughout the growing season. Chemical names used: alkylarylpolyethoxyethanol (Biofilm).
Physiological Responses in Potato Plants under Continuous Irradiation
Authors: Cao Weixing , Tibbitts Theodore W.
Published: January 2019

The physiological responses of four potato (Solanum tuberosum L.) cultivars to continuous irradiation were `determined in a controlled environment. Under a constant 18C and a constant photoperiod of 470 μmol·s-1·m-2 of photosynthetic photon flux, `Denali' and `Haig' grew well and produced large plant and tuber dry weights when harvested 56 days after transplanting. `Kennebec' and `Superior' were severely stunted, producing only 10% of the plant dry matter produced by `Denali' and `Haig'. The differences in leaf chlorophyll concentration and stomatal conductance were not consistent between these two groups of cultivars. The leaf net CO2 assimilation rates in `Kennebec' and `Superior' were lower, and intercellular CO2 partial pressures were higher than in `Denali' and `Haig'. These results indicate that inhibition of net CO2 assimilation in `Kennebec' and `Superior' was not due to a limiting amount of chlorophyll or to CO2 in the leaf tissues. Concentrations of starch in leaflets of `Kennebec' and `Superior' plants were only 10% of those in `Denali' and `Haig' plants, although soluble sugar concentrations were similar in the four cultivars. Therefore, the lower net CO2 assimilation rates in stunted `Kennebec' and `Superior' plants were not associated with an excess carbohydrate accumulation in the leaves.
Relationship of Flowering Time, Rate of Seed Germination, and Time of Leaf Budbreak and Usefulness in Selecting for Late-flowering Apples
Authors: Mehlenbacher Shawn A. , Voordeckers Anna M.
Published: January 2019

The relationship between dormancy of seeds and buds of apple (Malus × domestica Borkh.) might provide breeders with an early opportunity to select for delayed development. Seeds of late-flowering genotypes require much longer exposure to chilling temperatures than those of early flowering” genotypes, and they germinate over a much longer period. In three progenies that exhibit much variation for the two traits, seed germination time was correlated with time of leafing-out of the resulting seedlings, and could be used to select for delayed budbreak. However, selection would be ineffective when little genetic variation for seed germination and budbreak is present. Leafing-out ratings in the nursery in the 2nd year were highly correlated with those in the 3rd year, indicating that selection for late leafing in the nursery during the 2nd year would be more effective than selection based on seed dormancy, especially in progenies exhibiting little genetic variability for this trait. Breeders can effectively use both relationships by first eliminating early germinating seeds and then eliminating early leafing seedlings.
Dwarf Flower Stalk in Onion: Characterization, Genetic Control, and Physiological Response to Ethephon and Gibberellic Acid
Authors: Rabinowitch Haim D. , Friedlander Batya , Peters Ross
Published: January 2019

Recently, a dwarf scape mutant was found in `Autumn Beit-Alpha' onion (Allium cepa L.). The development of dwarf scape in onion, the genetic control of this attribute, and its response to external application of ethephon and GA3 were studied. Data from segregating populations conclusively showed that a single recessive gene, designated dw1, controls scape dwarfness in onions. Its expression is slightly modified by minor genes. Relatively slow growth and early cessation of cell elongation are the characteristics associated with scape dwarfness. A similar developmental pattern characterized emerging normal flower stalks treated with ethephon. GA3 application at 50 ppm had no effect on scape elongation of dwarf plants. In each of 3 years, dwarf genotypes always produced scapes about half the length of normal ones. The marked expression stability of the dw1 gene will facilitate its introduction into onion cultivars. Providing there is no negative pleiotropic effect, the dwarfness gene is expected to reduce lodging and, thus, improve mechanical harvest of onion seed. Chemical names used: 2-chloroethyl phosphoric acid (ethephon), gibberellic acid (GA3).
Effects of Nitrogen Fertilization and HPS Supplementary Lighting on Vegetable Transplant Production. II. Yield
Authors: Masson Jean , Tremblay Nicolas , Gosselin André
Published: January 2019

Transplants of celery (Apium graveolens L.), lettuce (Lactuca sativa L.), broccoli (Brassica oleracea italica L.), and tomato (Lycopersicon esculentum Mill.) grown in multicellular trays under natural light or with supplementary lighting of 100 μmol·s-1·m-2 (PAR) in factorial combination with four rates of N fertilization (100, 200, 300, and 400 mg•liter-1) were tested for productivity under field conditions. Celery was seeded once, lettuce twice, and broccoli and tomato three times. Broccoli and tomato were transplanted at two sites, celery and lettuce at one. Supplementary lighting had no effect on yields of celery, lettuce, and broccoli, but significantly increased yields of early seeded tomato. High rates of N fertilization (300 and 400 mg·liter-1) applied at the transplant stage improved yields for all the species.
Growth Dynamics following Planting of Cultivars of Juniperus chinensis
Authors: Gilman Edward F. , Kane Michael E.
Published: January 2019

Shoot and root growth were measured on Chinese juniper (Juniperus chinensis L. `Torulosa', `Sylvestris', `Pfitzeriana', and `Hetzii') 1, 2, and 3 years after planting from 1l-liter black plastic containers. Mean diameter of the root system expanded quadratically, whereas mean branch spread increased linearly. Three years after planting, root spread was 2.75 times branch spread, and roots covered an area 5.5 times that covered by the branches. Percentage of total root length located within the dripline of the plants remained fairly constant for each cultivar during the 3 years following planting. Root length density increased over time but decreased with distance from the trunk. During the first 2 years after planting, shoot mass increased faster than root mass. In the 3rd year, the root system increased in mass at a faster rate than the shoots. Root length was correlated with root weight. Root spread and root area were correlated with trunk cross-sectional area, branch spread, and crown area.
Soil Disinfection and Monoammonium Phosphate Fertilization Increase Precocity of Apples on Replant Problem Soils
Authors: Neilsen G.H. , Yorston J.
Published: January 2019

In an apple (Malus domestica Borkh.) orchard with a severe replant problem, tree size was increased by the 2nd year and number of fruit by the 3rd year by treating the planting hole soil with formalin or mancozeb plus monoammonium phosphate (MAP) fertilizer. Growth increases were evident each year for 4 years only for the MAP + formalin treatment. In a second orchard, with a less severe replant problem, planting-hole treatment with formalin or dazomet + MAP increased tree size by year 2. Number of fruit in year 2 was increased by formalin and mancozeb + MAP treatments, although this effect persisted in year 3 only for mancozeb + MAP. Leaf P concentrations were increased to high values in the first year by MAP fertilization but declined in subsequent years. Leaf Mn concentration also increased in one orchard, a consequence of fertilizer-induced acidification of planting hole soil and Mn uptake from the fungicide mancozeb. Chemical names used: tetrahydro-3,5-dimethyl-2 H -l,3,5-thiadiazine-2-thione (dazomet); 37% aqueous solution formaldehyde (formalin); Zn, Mn ethylene dithiocarbamate (mancozeb).
Broadleaf Weed Control in Strawberries with Postemergence-applied Diphenyl Ether Herbicides
Authors: Caylor A.W. , Dozier W.A. , Wehtje G. , Himelrick D.G. , McGuire J.A. , Pitts J.A.
Published: January 2019

The postemergence-active herbicides lactofen, fomesafen, and acifluorfen were applied to established matted-row strawberry plants (Fragaria × ananassa) and evaluated for broadleaf weed control and foliar phytotoxicity. Strawberries were evaluated for yield and fruit quality. Treatments were applied following June renovation. All herbicide treatments resulted in acceptable control of broadleaf weeds present at the time of application; however, sicklepod (Cassia obtusifolia) germinated after herbicide application. All treatments caused foliar injury within 3 days after application. No injury symptoms were evident 21 days after treatment due to new foliage development. Fomesafen and acifluorfen were the only herbicides to suppress runner count. Yields the following year were not reduced by herbicide treatments. Chemical names used: (±)-2-ethoxy-l-methy1-2-oxoethyl 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzate (lactofen); 5-[2-chloro-4-(trifluoromethyl)phenoxy] -N -(methylsu1fonyl)-2-nitrobenzamide (fomesafen); 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (acifluorfen).
Enhanced Vegetative Growth and Development of Processing Tomato by DCPTA Treatment of Seed
Authors: Keithly J.H. , Kobayashi H. , Yokoyama H. , Gausman H.W.
Published: January 2019

Application of DCPTA as a pregermination seed treatment (DCPTA plants) increased the seedling vigor, relative growth rate, harvestable yield, and yield quality of processing tomato (Lycopersicon esculentum Mill. cvs. UC82, VF6203, H100). When compared with controls, the growth rates of roots and shoots of 30 μm DCPTA plants were increased significantly (P = 0.05) during seed germination and midexponential growth. At fruit harvest, greenhouse-grown 30 μm DCPTA plants showed a 2- to 3-fold increase in leaf, stem, and root dry weight compared with that of controls. Improvements in the uniformity of fruit maturation significantly increased the harvestable fruit yields of greenhouse-grown DCPTA plants compared with that of controls. The total soluble solids (oBrix), glucose, fructose, and carotenoid contents of red-ripe fruits harvested from greenhouse- and field-grown DCPTA plants were significantly increased compared with controls. Chemical name used: 2-(3,4-dichlorophenoxy)triethylamine (DCPTA).
Water Relations of Salvia splendens `Bonfire' as Influenced by Potassium Nutrition and Moisture Stress Conditioning
Authors: Eakes D. Joseph , Wright Robert D. , Seiler John R.
Published: January 2019

The influence of K nutrition (25, 75, 150, 300, 450, and 600 mg K/liter) and moisture stress conditioning (MSC) (exposing plants to four sublethal dry-down cycles) on leaf water relations, evapotranspiration, growth, and nutrient content was determined for salvia (Salvia splendens F. Sellow `Bonfire'). Potassium concentration and MSC had an interactive influence on osmotic potential at full (π100) and zero (π0) turgor. Differences in osmotic potential between MSC and non-MSC plants for π100 and π0 increased with increasing K concentration. Increasing K concentration and MSC resulted in active osmotic adjustment and, consequently, increased cellular turgor potentials. Foliar K content increased with increasing K concentration and MSC. High K concentrations and MSC both reduced plant evapotranspiration on a per-plant and per-unit-leaf-area basis. Greatest shoot dry weight occurred for plants grown with 300 mg K/liter and non-MSC. Total leaf area increased with increasing K concentration, but MSC had little effect.
Inheritance of Resistance to Colletotrichum Species in Strawberry
Authors: Gupton Creighton L. , Smith Barbara J.
Published: January 2019

Experiments were conducted to estimate the relative importance of additive and dominance genetic variances and non-allelic interactions in the inheritance of resistance to Colletotrichum spp. in strawberry (Fragaria × ananassa Duch.). Progeny of 40 parents crossed in a Comstock and Robinson Design II Mating scheme were inoculated with three isolates of C. fragariae and one isolate of C. acutatum. Disease development on each plant was rated visually. Variance components were estimated and converted to genetic variances. Estimates of were six to 10 times higher than those for Within-family variance not accounted for by equaled 35% and 38% of the total genetic variance in females and males, respectively, indicating probable epistatic effects. The frequency distribution of disease severity ratings was bimodal in both experiments, suggesting major gene action. Narrow-sense heritability estimates were 0.37 and 0.26, and broad-sense heritability estimates were 0.87 and 0.85 for females and males, respectively. Narrow-sense heritability estimates are probably sufficient to produce gains from recurrent selection. Gains from selection of clonal value should be possible because of the high broad sense heritability estimates. It appears feasible to establish a broad genetic-based population resistant to Colletotrichum spp. from which selections could be evaluated per se and/or recombined to produce improved populations.
Genotype × Environmental Effects on Food Quality of Common Bean: Resource-efficient Testing Procedures
Authors: Shellie Krista C. , Hosfield George L.
Published: January 2019

Genetic and environmental interactions for bean cooking time, water absorption, and protein content were estimated with 10 dry bean (Phaseolus vulgaris L.) cultivars grown at three locations in Rwanda, Africa, during five consecutive harvests. The genotypic variance component was larger than genotype × environment variance components for the cooking time index and percent water absorption. No significant genotypic effect was observed for seed protein content. The phenotypic correlation (-0.37) between the cooking time index and percent water absorption was not strong enough to justify the use of water absorption as an indirect selection method for cooking time. The most efficient allocation of resources to evaluate the cooking time of common bean cultivars with a 25-pin bar-drop cooker was four field replications over two harvests at two locations. Water absorption was evaluated most efficiently with four field replications over two harvests at a single location.
Conservation of Citrus Germplasm in Vitro
Authors: Marin M.L. , Duran-Vila N.
Published: January 2019

A study was conducted to evaluate the potential of in vitro techniques for genetic conservation of citrus. A tissue culture system was developed using explants of juvenile `Pineapple' sweet orange. It consisted of: a) establishment of primary cultures from nodal stem segments followed by the recovery of plants in vitro; and b) successive cycles of secondary cultures consisting of the culture of nodal stem segments from in vitro-grown plants, rooting of shoots obtained from nodal stem segments, and recovery of whole plantlets. Two parameters, K and K', based on the multiplication factors of the different stages of primary and secondary cultures are proposed to monitor the system as a potential tool for genetic conservation of citrus. The system also can be successfully used for the conservation of juvenile tissues of two sweet orange varieties [Citrus sinensis (L.) Osb.], trifoliate orange [Poncirus trifoliata (L.) Raf.], Mexican lime [C. aurantifolia (Christm.) Swing.], and `Eureka' lemon [C. limon (L.) Burro. f.]. Chemical names used: 6-benzylaminopurine (BA); α- naphtbaleneacetic acid (NAA).
Improved Methods of Mechanically Thinning Peaches at Full Bloom
Authors: Baugher Tara A. , Elliott Kendall C. , Leach David W. , Horton B.D. , Miller Stephen S.
Published: January 2019

Studies were conducted on peach [Prunus persica (L.) Batsch] during 1988 to 1990 to test the performance of a tree-width rope-curtain bloom thinner and a rotating rope-curtain thinner. Six trips over the tree canopy were required with the tree-width rope curtain, and only one trip was required with the rotating curtain to thin to a spacing of about one flower per 9 cm of fruiting shoot length. Based on the number of flowers per square centimeter of branch cross-sectional area (CSA) immediately following thinning and the number of fruit per square centimeter of CSA following June drop, rope-curtain thinning was equal to hand-thinning at full bloom (FB). Rope-curtain thinning reduced hand-thinning time by 40% and increased harvest fruit weight by 10% to 20%. Research on various modifications in tree training/pruning indicated that performance of the mechanical thinner was negatively correlated with shoot density. Thinning was maximum on open-center-trained trees on which detailed pruning had been conducted to eliminate overlapping shoots.