bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Hydrogel on Physical Properties of Coarse-structured Horticultural Substrates
Authors: Fonteno W.C. , Bilderback T.E.
Published: January 2019

Addition of a polyacrylamide hydrogel to pine bark and pine bark + sand substrates had no effect on total porosity, regardless of incorporation rate. Container capacity was increased with increasing rate of hydrogel in both substrates. Air space in pine bark was slightly increased at the lowest rate but was reduced with higher incorporation rates. Air space in pine bark + sand was reduced with all hydrogel additions. The dry weigh', of hydrogel cubes recovered from both substrates was similar to amounts predicted. This result indicates that blending hydrogel granules into the substrates was uniform and did not contribute to variability in hydrogel studies. After allowing dry hydrogel granules to expand freely in distilled water for 24 hours, hydrogel granules expanded 317 and 372 times their dry weights at the lowest and highest rates, respectively. Reduction of expansion (in water) at higher rates may have been due to physical restriction of expansion. Conversely, recovered hydrogel cubes from substrates watered to drainage (-10% excess) for 6 weeks absorbed 25 to 55 times their dry weight while in the container. Subsequent rehydration of extracted gels in distilled water was greater for hydrogel cubes from the pine bark + sand medium (104 to 130) than in pine bark alone (51 to 88). Because of anomalies in hydraulic conductivity and pressure plate contact, three techniques were used to study unavailable water content in gels expanded in distilled water. Hydrogel cubes placed in direct contact with the pressure plate released ≈95% of their water at pressures ≤ 1.5 MPa. Effectiveness of ployacrylamide gels in coarse-structured substrates is influenced by physical restrictions to expansion in the substrate and hydraulic conductivity between the hydrogel cubes and the surrounding substrate.
Plasma Membrane Physicochemical Changes during Maturation and Postharvest Storage of Muskmelon Fruit
Authors: Lester Gene , Stein Eduardo
Published: January 2019

Changes in the physical and chemical properties of the plasma membrane from hypodermal mesocarp tissue of netted muskmelon (Cucumis melo L. var. reticulatus Naud.) fruit were compared in relation to the permeability changes of the same tissue during fruit maturation and storage at 4 or 24C. As muskmelon fruit progress from immaturity to maturity, and with storage of mature fruit at 4 or 24C, increased permeability of the hypodermal-mesocarp tissue occurs coincident with an increase in the saturation index of the plasma membrane phospholipids. Buoyant density of the plasma membrane from hypodermal mesocarp tissue increased from 1.13 to 1.14 g·cm-3 during fruit maturation. Vanadate-sensitive ATPase (EC 3.6.1.35) activity was highest in mature fruit at harvest. After 10 days of storage, vanadate-sensitive ATPase activity was much lower in fruit kept at 24C than in those kept at 4C. The decrease in vanadate-sensitive ATPase activity in fruit stored at 24C was correlated with increased hypodermal-mesocarp membrane permeability. We suggest that biochemical changes affecting the lipid matrix of the plasma membrane influence fruit membrane permeability and possibly muskmelon storage life.
Antidesiccant Compounds Improve the Survival of Bare-root Deciduous Nursery Trees
Authors: Englert John M. , Warren Keith , Fuchigami Leslie H. , Chen Tony H.H.
Published: January 2019

Desiccation stress during the postharvest handling of bare-root deciduous trees can account for dieback and poor regrowth after transplanting. Desiccation tolerance of three bare-root deciduous hardwood species was determined at monthly harvest intervals from Sept. 1990 through Apr. 1991. Among the three species tested red oak (Quercus rubra L.) was most tolerant to desiccation, followed by Norway maple (Acer platanoides L.) and Washington hawthorn (Crataegus phaenopyrum Medic.). Maximum desiccation tolerance of all three species occurred during the January and February harvests. Of 20 film-forming compounds tested, the antidesiccant Moisturin was the most effective in reducing water loss from bare-root trees during desiccation stress and in improving survival and plant performance during re-establishment in the laboratory, greenhouse, and field. Moisturin-treated plants lost up to 80% less water than untreated plants. Washington hawthorn seedlings treated with Moisturin before severe desiccating conditions had the highest survival, lowest dieback/plant, and highest root growth ratings. The results indicate that Moisturin is an effective means of overcoming postharvest desiccation stress in desiccation sensitive plants, such as Washington hawthorn.
Chilling of Endodormant Peach Propagules: III. Budbreak and Subsequent Growth of Physiologically Dwarfed to Near Normal Seedlings
Authors: Frisby James W. , Seeley Schuyler D.
Published: January 2019

We studied the response of physiologically dwarfed (PD) to near normal peach [Prunus persica (L.) Batsch] seedlings (`Johnson Elberta' seeds) to various chilling treatments. Peach seedlings were obtained by forcing seeds that had been subjected to a brief stratification treatment. Seedlings were divided into four types (groups) according to the length of the primary stem and the presence and size of lateral branches. The seedlings were used in a chilling study with treatments of five durations (20 to 60 days) at four temperatures (2 to 14C). Terminal shoot growth and lateral budbreak were recorded 17 days after forcing. Shoot and leaf dry weight were obtained after seedlings had grown for 64 days. Budbreak and growth improved with the duration of the chilling treatment. Generally, 7C was the best chilling temperature, with 2 or 10C only slightly less effective. Treatment at 14C did not promote budbreak or growth. Budbreak and growth had significant interactions between treatment duration and temperature. The seedling type and treatment duration interaction was significant for terminal shoot length, lateral budbreak, and leaf dry weight, but were probably the result of differences between the seedling types before treatment and not true interactions with the length of the treatment. There was a significant interaction between the seedling type and treatment temperature on terminal shoot growth. Subsequent shoot growth did not differ significantly between the seedling types after similar chilling treatments. Thus, shoot growth was the best indicator of the chilling process of `Johnson Elberta' peach seedlings. Indicators of dormancy removal such as lateral budbreak or terminal shoot growth after 17 days forcing were not good predictors of subsequent seedling growth.
Carbohydrate Metabolism and Possible Mechanisms of Leaf Blackening in Protea neriifolia under Dark Postharvest Conditions
Authors: McConchie Robyn , Lang N. Suzanne
Published: January 2019

During a 7-day dark postharvest period, Protea neriifolia R.Br. leaf blackening was significantly reduced on floral stems treated with a 24-h 20% sucrose pulse compared with continuous holding in a 0.5% sucrose vase solution or removal of the flowerhead. Leaf blackening on vegetative stems was similar to that on the 20% sucrose-pulsed floral stems. Leaf starch and sucrose concentration profiles demonstrated that stems with reduced leaf blackening maintained higher levels of those carbohydrates during the early postharvest period. Conversely, leaf starch and sucrose reserves were quickly depleted in stem treatments that resulted in early blackening symptoms. Starch concentrations in all treatments of stems dropped 70% to 82% within 24 h of harvest, suggesting that leaf blackening may be initiated during shipping. Ethylene production was not associated with leaf blackening in any treatment. Lipid peroxidation did not differ among floral treatments nor did it increase over the postharvest interval. Oxidized glutathione (GSSG) concentration increased only with the 20% pulsed stems and was not related to leaf blackening. After an initial decrease, leaf respiration rate was generally maintained regardless of treatment. Collectively, these data are consistent with the hypothesis that carbohydrate depletion is the initiating factor in leaf blackening and is accelerated by inflorescence sink demand. We suggest that membrane degradation does not necessarily precede leaf blackening.
Blueberry Germplasm Screening at Several Soil pH Regimes. I. Plant Survival and Growth
Authors: Finn Chad E. , Luby James J. , Rosen Carl J. , Ascher Peter D.
Published: January 2019

Thirty-three seedling progenies from crosses among Vaccinium corymbosum L., V. angustifolium Ait., and V. corymbosum/V. angustifolium hybrid-derivative parents, and `Northblue', `Northsky', and `Northcountry' were grown for 2 years at three soil pH levels at Becker, Minn. Iron sulfate and lime were incorporated to amend the soil to pH levels of 4.0 and 6.5, respectively; the native soil, pH 4.5, was the third pH regime. The plants grew well in the low pH regime, poorly in the high pH regime, and intermediately in the native pH regime. Variation among populations was significant for all traits except vitality 18 months after being planted, and pH treatment affected all traits. The pH regime × population interactions were not significant for any of the plant performance characteristics. Nondestructive subjective and objective measurements were positively and highly correlated with total plant dry weight. Therefore, populations could be effectively evaluated for tolerance to higher pH without destroying the plant. Vaccinium angustifolium was not a general source of tolerance to higher pH, but some populations derived from V. angustifolium were tolerant of high soil pH.
Blueberry Germplasm Screening at Several Soil pH Regimes. II. Plant Nutrient Composition
Authors: Finn Chad E. , Rosen Carl J. , Luby James J. , Ascher Peter D.
Published: January 2019

Seedlings from crosses among Vaccinium corymbosum L., V. angustifolium Ait, and V. corymbosum/V. angustifolium hybrid-derivative parents, and micropropagated `Northblue', `Northsky', and `Northcountry' plants, were grown for 2 years at Becker, Minn., in low (5.0) and high (6.5) soil pH regimes. Nutrient composition expressed as a concentration and total content was determined for P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B in the aboveground portion of the plant. Except for Fe, the pH regime effects on aboveground plant nutrient concentration and total content were much larger than population or population × pH regime interaction effects. Population × pH regime interactions were detected for all nutrients expressed as a concentration, except for P. Generalizations about plant performance and nutrient concentration of the plant could only be made in the context of a given pH regime. At low pH, P and Mn tissue concentrations increased and Ca, Mg, and B concentrations decreased as the percentage of lowbush ancestry increased. At high pH, K, Cu, and B concentrations decreased as the percentage of lowbush ancestry increased. Overall plant performance on the higher pH soils appeared to be positively correlated to aboveground tissue concentrations of Mn, K, and Cu. When expressed as total content, population × pH regime effects were only significant for tissue Mn. Differences in total nutrient content attributed to soil pH were primarily related to differences in plant dry weight.
Climate Influences Vegetative and Reproductive Components of Primocane-fruiting Red Raspberry Cultivars
Authors: Privé Jean-Pierre , Sullivan J.A. , Proctor J.T.A. , Allen O.B.
Published: January 2019

Climatic elements (solar radiation, daylength, water supply, growing degree days (GDD), corn heat units (CHU), soil, and air temperatures) were monitored to determine which elements could account for the variability in yield of primocane-fruiting red raspberry (Rubus idaeus L.) cultivars. The climatic elements were classed as either having a major or minor influence on the vegetative and reproductive components, based on the frequency of the significance of the multiple regression coefficients. Soil temperature and water supply had a major influence, while daylength, solar radiation, and aboveground temperature (i.e., air, GDD, or CHU) had a lesser influence on these components. Soil temperature had the largest influence during April and May, while water supply was equally influential at all times during the season. Air temperature and solar radiation had their largest influence during the period of flower initiation and development (i.e., June and July), while daylength was most influential from June to October. Berry count, weight, and yield had the highest frequency of associations among the climatic elements, indicating the complexity of the association between these yield components and climate. Total number of nodes/cane, length of the fruiting section/cane, and the harvest period showed the fewest number of associations. Not all cultivars responded similarly to changes in their yield components. `Autumn Bliss' was less sensitive to climatic variation than either `Heritage' or `Redwing'. When `Redwing' was the anomaly, it was usually related to air or soil temperatures.
Genetic Variance Components and Heritabilities of Several Avocado Traits
Authors: Lavi Uri , Lahav Emanuel , Degani Chemda , Gazit Shmuel , Hillel Jossi
Published: January 2019

Genetic variance components for avocado (Persea americana Mill.) traits were estimated to improve avocado breeding efficiency. The additive and nonadditive genetic variance components were calculated from the variances between and within crosses. In all nine traits examined, i.e.-anise scent, fruit density, flowering intensity, fruit weight, harvest duration, inflorescence length, seed size, softening time, and tree size-a significant nonadditive genetic variance was detected. Additive genetic variance in all traits was lower and nonsignificant. The existence of major nonadditive variance was indicated also by narrow-sense and broad-sense heritability values estimated for each trait. Therefore, parental selection should not be based solely on cultivar performance. Crosses between parents of medium and perhaps even low performance should also be included in the breeding program.
Consumer Tastes, Preferences, and Behavior in Purchasing Fresh Tomatoes
Authors: Brumfield Robin G. , Adelaja Adesoji O. , Lininger Kimberly
Published: January 2019

Face-to-face interviews of produce customers at Kings Super Markets in New Jersey yielded data on consumers' tastes and preferences, quantities purchased, and prices paid for fresh tomatoes (Lycopersicon esculentum Mill.). Purchase behavior indicated that during the local season, consumers preferred tomatoes grown in New Jersey to tomatoes from other origins. Data were fitted to demand equations to determine the factors affecting demand for fresh tomatoes. Tomato origin significantly influenced consumer purchases. Consumer perceptions of product characteristics such as color, freshness nutrition, and appearance do not appear to significantly influence tomato purchase patterns. However, prices of the) tomatoes or substitutes and income were important determinants of quantity purchased of both New Jersey grown and other tomatoes. New Jersey grown tomatoes were generally perceived to be of superior quality.
Forecasting the Harvest Date and Yield of Sweet Corn by Complex Regression Models
Authors: Lass L.W. , Callihan R.H. , Everson D.O.
Published: January 2019

Predicting sweet corn (Zea mays var. rugosa Bonaf.) harvest dates based on simple linear regression has failed to provide planting schedules that result in the uniform delivery of raw product to processing plants. Adjusting for the date that the field was at 80% silk in one model improved the forecast accuracy if year, field location, cultivar, soil albedo, herbicide family used, kernel moisture, and planting date were used as independent variables. Among predictive models, forecasting the Julian harvest date had the highest correlation with independent variables (R2 = 0.943) and the lowest coefficient of variation (cv = 1.31%). In a model predicting growing-degree days between planting date and harvest, R2 (coefficient of determination) = 0.85 and cv = 2.79%. In the model predicting sunlight hours between planting and harvest, R2 = 0.88 and cv = 6.41%. Predicting the Julian harvest date using several independent variables was more accurate than other models using a simple linear regression based on growing-degree days when compared to actual harvest time.
Gas Exchange and Chlorophyll Content of `Tifblue' Rabbiteye and `Sharpblue' Southern Highbush Blueberry Exposed to Salinity and Supplemental Calcium
Authors: Wright Glenn C. , Patten Kim D. , Drew Malcolm C.
Published: January 2019

`Tifblue' rabbiteye blueberry (Vaccinium ashei Reade) and `Sharpblue' southern highbush blueberry (primarily V. corymbosum) were treated with 0, 25, or 100 Mm Na+ as Na2SO4 or NaC1, and 0, 1, 3, or 10 Mm supplemental Ca2+ in sand culture in the greenhouse. Greatest stomatal conductance (gs) and net assimilation (A) occurred in unsalinized `Tifblue' plants not given additional Ca2+. Stomatal conductance, A, transpiration (E), and xylem water potential(Ψ)of `Tifblue' and `Sharpblue' plants were all lowered as salinity increased, and these effects were more pronounced with NaCl than with Na2SO4. After 63 days, for plants given 100 Mm Na+ as NaCl, gs and net assimilation rate were reduced to only 10% of the unsalinized controls, while for plants salinized with 100 mm Na+ as Na2SO4, gs and A were 35% and 43%, respectively, of unsalinized controls. Leaf necrosis was more extensive on `Sharpblue' plants given NaCl than on `Tifblue' plants. Neither Ca2+ nor Na+ treatments led to severe chlorosis; reductions in leaf chlorophyll content were mainly due to necrosis. The Na+- induced reduction in gas exchange was associated with negative Ψw Ca2+ deficiency, or a combination of these factors. Additional factors leading to inhibition of gas exchange in NaCl- stressed plants include Cl- toxicity and leaf necrosis. Calcium supplements were unable to ameliorate NaCl damage in `Tifblue' or `Sharpblue' plants, possibly because of the inability of Ca2+ to counter Cl- entry and toxicity. In contrast, additional Ca2+ improved gs, A, Ψw, and leaf chlorophyll content of `Tifblue' plants that received Na2SO4. For plants treated with 25 mm Na+ as Na2SO4 and 1 mm Ca2+, gs was 1.5 to 2.5 times higher than in plants without added Ca2+. Low (1 mm) concentrations of Ca2+ were more effective in ameliorating the effects of 100 mm Na+ as Na2SO4. than were 3 or 10 mm Ca2+ supplements, possibly because higher Ca2+ concentrations damaged the metabolism of the calcifuge blueberry.
Phytotoxic Response of `Dancy' Tangerine to High-temperature, Moist, Forced-air Treatment for Fruit Fly Disinfestation
Authors: Shellie Krista C. , Firko Michael J. , Mangan Robert L.
Published: January 2019

Early season degreened `Dancy' tangerines (Citrus reticulata Blanco) were size graded and subjected to high-temperature, moist, forced-air (HTMFA) treatments using air at 45, 46, or 48C for 0, 1, 2, 3, or 4 hours. The phytotoxic response of fruit to the beat treatments was evaluated immediately after treatment and weekly during 3 weeks of cold (4C) storage. Mortality of nonfeeding, third instar Mexican fruit fly [(Anastrepha ludens (Loew)] larvae was estimated for each time-temperature heat treatment combination in water baths that simulated the heating and cooling profiles of heat-treated fruit. Unacceptable phytotoxic symptoms, such as inferior flavor and darkened flavedo tissue, were observed when fruit was treated at 46 or 48C. Fruit heated with 45C forced moist air had flavedo color change(ΔL*)percent juice yield, soluble solids concentration, and flavor ratings that were statistically similar to ratings for unheated, control fruit. An HTMFA treatment of 3 or 4 hours at 45, 46, or 48C and subsequent cooling was sufficient to kill 100% of naked larvae in water baths. Market quality of fruit was maintained after a 4-hour HTMFA treatment at 45C, and 100% mortality of naked larvae occurred after 3 hours at 45C.
Short-term Controlled Atmosphere Storage Improved Quality of Several Apple Cultivars
Authors: Drake S.R.
Published: January 2019

Controlled atmosphere (CA) storage for 30 or 60 days reduced quality losses for `Jonagold', `Golden Delicious', `Delicious', `Granny Smith', and `Fuji' apples (Malus domestica Borkh.). After 30 days `Jonagold' and `Golden Delicious' from CA were firmer, had higher acidity, and were less yellow (more green) than apples from regular atmosphere (RA) storage. `Delicious' and `Granny Smith' were firmer after 60 days of CA storage than fruit from RA. In addition, `Granny Smith' from CA had more acid and were greener than apples from RA. After 8 days of ambient storage, little loss in firmness and no loss in acid content occurred with `Jonagold' or `Golden Delicious' from CA compared to the significant loss in firmness and acid when stored in RA. After ambient storage for 8 days, `Jonagold', `Golden Delicious', and `Granny Smith' retained a freshly harvested apple color with more green and less yellow development when stored in CA rather than RA. In `Fuji', the treatments had no effect except for improved acid retention if stored in CA. A combination of 30 days CA followed by 30 days RA produced `Jonagold', `Golden Delicious', and `Delicious' that were superior in quality to apples from 60 days RA.
Production Characteristics of the United States Pecan Industry
Authors: Wood Bruce W.
Published: January 2019

The cyclic, alternate bearing and correlative aspects of U.S. produced pecan [Carya illinoinensis (Wangenh.) K. Koch] nuts are characterized. An attempt to forecast production using stepwise autoregressive techniques identified a national level biennial cycle for cultivar (CV) and seedling (SC) class nuts and a novemennial (9 year) cycle for SG class nuts. The intensity of the biennial cycle at the national level has generally been low to moderate over the last 50 years for CV and SG class nuts with no clear time trend being expressed. During the most recent years (1979-1991), national production of CV class nuts has not exhibited pronounced bienniality, whereas that of SG class nuts exhibited a moderate bienniality. The nature of the the irregularity of cycling of U.S. and state production appears to nullify the use of univariate polynomial equations as a practical tool for accurately forecasting nut production. Nut production within individual states was also cyclic, with 2-, 3-, 5, 6-, 10-, 12-, 14-, 15-, and 16-year cycles, depending on state and nut class. The most intense contemporary biennial cycles for CV class nuts were from Oklahoma, South Carolina, and North Carolina, whereas cycling of SG class nuts was most intense in Texas and Oklahoma. Correlations of production within and among states indicated that most interrelationships are relatively weak; however, national production of CV class nuts are highly correlated (r = 0.96) with the production of CV class nuts in Georgia, whereas that of SG class nuts is most correlated with that of Louisiana.
Pattern of Seasonal Water Use of Asian Pears Determined by Lysimeters and the Heat-pulse Technique
Authors: Caspari Horst W. , Behhoudian M. Hossein , Chalmers David J. , Renquist A. Richard
Published: January 2019

Seasonal water use data are presented for 4-year-old Pyrus serotina Rehder cv. Hosui growing in drainage lysimeters and trained onto a Tatura trellis. Weekly water use (WU) was calculated using the mass balance approach. For 8 consecutive weeks during late summer, instantaneous WU was also measured by the compensation heat-pulse technique for measuring sap flow. Although good agreement was found between the two methods for 4 weeks after probe installation, discrepancies increased after this time. Water use was highest in early to mid-January in New Zealand, averaging ≈8 liters/tree per day, or 2 liters·m-2 canopy surface area/day. Total water use over the growing season was 1070 liters/tree, or 245 liters·m-2 canopy surface area. The correlation coefficient between weekly WU and evaporation from a nearby Class A pan was 0.81 for the season. Weekly crop coefficients thus calculated for the well-watered trees ranged from 0.15 to 0.55 and 0.20 to 0.83 when calculated using canopy surface area and projected ground area, respectively. Low values were due to low values of canopy leaf area early in the season. Withholding irrigation during three periods resulted in a gradual decline in water use. Water-stressed trees had a lower predawn water potential than fully irrigated trees. This pattern was followed by a more-rapid decline during the morning, and a slower recovery during late afternoon and early evening. Midday leaf water potential never fell below -2.5 MPa.
Patterns of Soil and Tree Water Status and Leaf Functioning during Regulated Deficit Irrigation Scheduling in Peach
Authors: Girona J. , Mata M. , Goldhamer D.A. , Johnson R.S. , DeJong T.M.
Published: January 2019

Seasonal patterns of soil water content and diurnal leaf water potential (LWP), stomatal conductance(gs), and net CO2 assimilation (A) were determined in a high-density peach [Prunus persica(L) Batsch cv. Cal Red] subjected to regulated deficit irrigation scheduling. The regulated deficit irrigation treatment caused clear differences in soil water content and predawn LWP relative to control irrigation treatments. Treatment differences in midday LWP, gs, and A were also significant, but not as distinct as differences in predawn LWP. Leaves on trees subject of the deficit irrigation treatment were photosynthetically more water-use-efficient during the latter part of the stress period than were the nonstressed trees. Midday LWP and gs, on trees that received the regulated deficit irrigation treatment did not recover to control treatment values until more than 3 weeks after full irrigation was resumed at the beginning of state III of fruit growth, because of water infiltration problems in the dry soil caused by the deficit irrigation. The regulated deficit irrigation treatment caused only a 8% reduction in trunk growth relative to the control, but resulted in a 40% savings in irrigation requirements.
The Role of Phosphorus as an Abscission-inducing Agent for Olive Leaves and Fruit
Authors: Banno Kiyoshi , Martin George C. , Carlson Robert M.
Published: January 2019

Citrate-phosphate buffer induced olive (Olea europaea L.) leaf abscission at pH 3, 5, or 7. Of several sources of P-induced leaf abscission, NaH2PO4 was the most effective. Sensitivity to P was shown by leaf abscission, leaf desiccation, or both among 32 species representing 22 genera. Applied P accumulates in petioles, but its effect on abscission does not seem to depend on ethylene production. The low P content in the ethephon molecule may have an additive effect in ethephon-induced abscission. Stem-fed NaH2PO4 or ethephon resulted in total leaf and fruit abscission. Of the chemicals applied as a foliar treatment, only NaH2PO4 caused fruit abscission with minimal leaf loss. Adding Al2O3 to adsorb P in treatment solutions delayed the abscission effect of ethephon and NaH2PO4. Adding glycerol to NaH2PO4 increased fruit abscission from 50% to ≈80% and leaf abscission from ≈9% to 18%. The presumed effect of glycerol is from slowing the drying rate and thereby increasing P penetration into the fruit abscission zone. The pedicel-fruit cavity is a collection basin for spray accumulation that is not present in the leaf petiole attachment to the stem. This morphological difference probably leads to greater absorption of abscission-inducing materials by fruit. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
Auxin-induced Ethylene Synthesis during Rooting and Inhibition of Budbreak of `Royalty' Rose Cuttings
Authors: Sun Wen-Quan , Bassuk Nina L.
Published: January 2019

Single-node `Royalty' rose (Rosa hybrida L.) cuttings were used to examine the relationship between adventitious root formation, budbreak, and ethylene synthesis following IBA treatment. IBA was applied as a lo-second basal quick dip before rooting, and AIB, GA3, STS, and ethephon were applied either as basal dips or foliar sprays. IBA application increased rooting and inhibited budbreak of cuttings. IBA 2 600 mg·liter-1 greatly inhibited budbreak during 4 weeks of rooting. IBA treatment stimulated ethylene synthesis, which was inversely correlated with budbreak of cuttings. Ethephon also significantly inhibited budbreak. Budbreak of rose cuttings was completely prevented by repeated ethephon sprays used to maintain high endogenous ethylene levels during the first 10 days. Treatment with STS, an ethylene-action inhibitor, improved budbreak. The inhibition of budbreak by IBA treatment resulted primarily from elevated ethylene levels. Root initiation and root elongation of cuttings initially inhibited budbreak, but later promoted budbreak. Chemical names used: indole-3-butyric acid (IBA); gibberellic acid (GA3); silver thiosulfate (STS); AIB, aminoisobutyric acid (AIB); (2-chloroethyl)-phosphoric acid (ethephon).
Growth, Fruit Yield, and Ion Concentration in Tomato Genotypes after Pre- and Post-emergence Salt Treatments
Authors: Bolarín M.C. , Pérez-Alfocea F. , Cano E.A. , Estañ M.T. , Caro M.
Published: January 2019

The effects of increasing salinity on dry weight and ion concentration of shoots at various growth stages and on fruit yield in four tomato (Lycopersicon esculentum Mill.) genotypes were assessed. The salt treatments (35, 70, and 140 mm NaCl) were applied pre-emergence (seed sowing) (pre-E) and post-emergence (four-leaf stage) (post-E) and maintained during plant growth. Genotype salt tolerance, measured as shoot dry weight in response to increases in salt concentration, varied depending on plant growth stage and salt application time. When salt was applied pre-E, salt tolerance increased with plant age, whereas when applied post-E, 45-day-old plants were the most salt tolerant. Mature plants were similarly salt tolerant independent of the growth stage at which the salt treatments began. However, fruit yield of all genotypes was higher when salt was applied pre-E than post-E. Shoot dry weight decreased as shoot Cl and Na ion concentrations increased. During early growth stages, pre-E salt-treated plants had the highest Cl-and Na+ concentrations and the lowest shoot dry weights. However, at the advanced stages, shoot Cl- and Na Concentrations were equal for both salt application times. These results show that the plants must adapt to salinity during a period that allows them to develop a mechanism to regulate internal Cl- and Na+ concentrations and, thus, grow under high salinity.
Comparison of Greenhouse Methods for Assessing Resistance to Bacterial Leaf Spot in Plum
Authors: Topp B.L. , Sherman W.B. , Stall R.E. , Minsavage G.V. , Wilcox C.J.
Published: January 2019

Four greenhouse leaf inoculation methods for screening Japanese plum (Prunus salicina L. and hybrids) for resistance to Xanthomonas campestris pv. pruni (Smith) Dye were compared for repeatability, ability to differentiate among plant genotype responses, and correlations with field ratings. Clonally propagated trees were inoculated artificially in a greenhouse by immersing leaves in 2.5 × 108 cfu/ml inoculum (DIP), rubbing the adaxial side of leaves with a slurry of 2.5 × 108 cfu/ml inoculum and Carborundum powder (CARB), infiltrating leaves with 5 × 105 cfu/ml inoculum using a needle-less syringe (INFS), and infiltrating with 5 × 106 cfu/ml inoculum (INF6). No greenhouse method was superior in all assessment categories. The CARB method was most repeatable (t = 0.78) but had a low Spearman's correlation (rs = 0.29), indicating that greenhouse rankings did not correspond closely with field rankings. The INF6 method was unsuitable because it did not differentiate between plant genotypes. The DIP method appeared most suitable, having moderate repeatability (t = 0.46) for four observations per leaf and moderate Spearman's correlation with field performance (rs = 0.56). The INF5 method may be appropriate for identifying bacterial spot resistance that is associated with resistance in the leaf mesophyll.
Evaluation of Brown Rot Resistance and its Relation to Enzymatic Browning in Clingstone Peach Germplasm
Authors: Gradziel T.M. , Wang Dechun
Published: January 2019

Rate of brown rot lesion development following inoculation with Monilinia fructicola (Wint.) honey varied within clingstone peach (Prunus persica (L.) Batsch) germplasm evaluated in 1990 and 1991. High levels of resistance were identified in selections derived from the Brazilian clingstone peach cultivar Bolinha. Resistance appeared to be limited to the epidermal tissue. No relation was detected between brown rot resistance and concentration of phenolic compounds or polyphenol oxidase activity in the susceptible California germplasm. An inverse relation was observed between disease severity and rating for phenolic-related discoloration when `Bolinha' derived selections were analyzed. A moderate positive correlation was observed for all germplasm tested between genotype means for phenolic content and enzymatic browning. Any causal relationship, if it exists, between phenolic content and brown rot resistance is obscured by an array of physical and chemical changes in the maturing fruit.
Production, Growth, and Nut Quality in Pecans under Water Stress Based on the Crop Water Stress Index
Authors: Garrot Donald J. , Kilby Michael W. , Fangmeier Delmar D. , Husman Stephen H. , Ralowicz Andrew E.
Published: January 2019

The crop water stress index (CWSI), based on the relationship between the canopy temperature of a well-watered plant in full sunlight and the atmospheric water content, numerically quantifies water stress. A 4-year study was established to determine the long-term effect of water application levels on production, nut quality characteristics, and growth of pecans [Carya illinoinensis (Wangenh.) C. Koch cv. Western Schley]. Highest yields were attained when trees were relatively nonstressed (CWSI ≤ 0.08). Trees subjected to moderate water stress before irrigation (CWSI ≥ 0.20) showed reduced yield, nut weight, and tree growth, although water-use efficiency increased. With water management practices resulting in maximum yield, nut size, and tree growth (CWSI ≤ 0.08), tree water use varied up to 44% in the same orchard, depending on crop load and yearly climatic variations.
Root-medium Nutrient Concentration and Growth of Poinsettia at Three Fertilizer Concentrations and Four Leaching Fractions
Authors: Yelanich Mark V. , Biernbaum John A.
Published: January 2019

`V-14 Glory' poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) were fertilized at every irrigation with solutions containing 7, 14, or 28 mol N/m3 at four leaching fractions (LFs) of 0, 0.1 to 0.2, 0.3 to 0.4, or 0.5 to 0.6 or with subirrigation. The N applied ranged from 44 to 464 mmol/pot applied over 12 to 25 irrigations. Medium NO3-N and K concentrations and electrical conductivity were highest at the highest fertilizer concentration and lowest LF throughout cropping. Phosphorous concentration in the medium declined until week 12, when phosphoric acid was added for pH adjustment. Subsequently, medium P concentration was highest in treatments with the highest LF. Final shoot height, plant dry mass, and leaf area decreased as fertilizer concentration increased. Highest fresh mass, bract area, and shoot: root ratio were obtained with 14 or 28 mol N/m3 and a 0.55 LF or with 7 mol N/m3 and a 0.15 LF. Leaf N concentration was lower with subirrigation than with surface application. Leaf P and Mg were lower at higher LFs or with subirrigation, but leaf K was not influenced by the treatments.
Training Systems Affect Canopy Light Exposure and Shelf Life of Long English Cucumber
Authors: Klieber A. , Lin W.C. , Jolliffe P.A. , Hall J.W.
Published: January 2019

Various stem-training systems were applied to greenhouse-grown `Mustang' cucumber (Cucumis sativus L.) plants at two production stages. Training systems determined the number of stems per plant, orientation of laterals, and leaf: fruit ratio. Training systems permitting high canopy light penetration resulted in darker fruit and a longer shelf life. Shelf life was positively related to rapid fruit growth in Expt. 1 but not in Expt. 2. Training systems to achieve a long shelf life of greenhouse-grown long English cucumber are described.
Amelioration of Chilling Injury in Phaseolus vulgaris L. by GLK-8903
Authors: Flores-Nimedez Agnes A. , Li Paul H. , Shin Charles C.
Published: January 2019

GLK-8903, an experimental product whose main ingredient is produced by hydrogenation of a primary alcohol extracted from plants, showed significant potential in protecting bean (Phaseolus vulgaris L.) plants from chilling injury. The GLK-8903 protection mechanism was assessed by examining several physiological and biochemical responses. The decline in leaf water potential and the increase in osmotic potential caused by chilling exposure to 4C (day/night) were minimized by the application of GLK-8903. Chilling causes an increase in electrolyte leakage, an indication of chilling injury of the plasma membrane. Increased electrolyte leakage was reduced significantly in the GLK-8903-treated plants during chilling. This minimized leakage may be due to less damage of the plasma membrane. Plasmolysis and deplasmolysis studies of the epidermal cells suggest that GLK-8903 is able to reduce the plasma membrane perturbation in the chilling environment, as evident by: 1) the lower permeability coefficient to urea at 4C, and 2) the swelling of protoplasts in the cells of untreated tissues after chilling exposure with no swelling of the protoplast being observed in the GLK-8903-treated cells. Malondialdehyde (MDA), a product of lipid peroxidation, increased more in untreated controls than in treated plants exposed to 4C. Plasma membrane ATPase activity decreased less in GLK-8903-treated plants than in untreated controls after 3 days at 4C. The mechanism of GLK-8903-alleviated chilling injury is discussed.
Allozyme Inheritance in Tetraploid Sour Cherry (Prunus cerasus L.)
Authors: Beaver J.A. , Iezzoni A.F.
Published: January 2019

Inheritance for seven enzyme loci was determined in seeds produced from crosses and self-pollinations involving four sour cherry parents and one open-pollinated ground cherry (P. fruticosa Pall.) parent. Segregation data were used to identify allozymes and determine whether sour cherry is a naturally occurring allo- or autotetraploid. Three allozymes were identified at the 6-Pgd-1 locus, and two were identified at each of the following loci: Pgi-2, Lap-1, Adh-1, Idh-2, Pgm-2, and 6-Pgd-2. Segregating allozyme patterns for the diagnostic loci Idh-2, Pgm-2, 6-Pgd-1, and 6-Pgd-2 tit disomic inheritance models and thus confirmed the allotetraploid hypothesis for sour cherry. Chi-square tests of independence between loci indicated that Pgi-2, Adh-1, Idh-2, 6-Pgd-1, and 6-Pgd-2 were not linked.
Improved Survival of in Vitro-stored Rubus Germplasm
Authors: Reed Barbara M.
Published: January 2019

Medium-term in vitro cold storage of Rubus germplasm was investigated using various temperatures, photoperiods, and storage containers. Shoot cultures of several Rubus taxa were grown either in tissue-culture hags or 20 × 150-mm glass tubes. Cultures stored at 10C in darkness were in poor condition after 6 months. Overall survival and condition ratings were significantly better for bags than tubes when cultures were kept at 4C. Contamination was present in 14% of the tubes, but only 3% of the bags. Addition of a 12-hour photoperiod to 4C storage significantly improved both condition ratings and survival percentages of many individual genotypes. Evaluation of the 250-accession germplasm collection after 12 months at 4C (dark) showed 92% of accessions in bags and 85% in tubes in suitable condition to remain in storage. Storage of cold-sensitive genotypes in tissue-culture bags at 25C with a 16-hour daylength was extended to 9 months when the MS-medium nitrogen level was reduced to 25% of standard concentration. Survival of `Mandarin' raspberry stored for 9 months improved from 40% at 4C (100% N) to 90% at 25C (25% N). Results of these studies suggest that most Rubus germplasm can be stored safely at 4C with 12 hours of light. Plastic tissue-culture bags are preferred over tubes due to higher survival and lower contamination rates. Storage at 25C on reduced-nitrogen medium is an alternative method for cold-sensitive genotypes.
Identifying Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] Cultivar Breeding Lines Using Random Amplified Polymorphic DNA (RAPD) Markers
Authors: Wu Lin , Lin Hong
Published: January 2019

The polymerase chain reaction (PCR) and RAPD fragments are potentially useful methods for identifying turfgrass cultivar breeding lines. RAPD markers were studied in 25 vegetatively propagated buffalograss lines using oligonucleotide random primers and agarose-gel electrophoresis to determine their potential for identifying cultivar breeding lines. The variation of RAPD markers was extensive. The RAPD markers produced by one random primer were sufficient to separate the 25 buffalograss lines. Cluster analysis baaed on' the RAPD markers produced by two random primers revealed that the 25 buffalograss lines generally fell into two groups: diploid and hexaploid. Three DNA extraction methods—sarcosyl lysis-chloroform extraction-isopropanol precipitation, sodium dodecyl sulfate (SDS) lysine-isopropanol precipitation, and boiling in the presence of Chelex-100 resin—and fresh or oven-dried tissues were tested for reproducibility of RAPD markers. The three DNA extraction methods, using dry or fresh plant tissues, produced highly comparable RAPD marker profiles. More than 80%1 of the RAPD markers was consistently detected in six replicate analyses. The above studies demonstrate that small quantities (5 mg) of oven-dried leaf tissue and several DNA extraction methods can be used for buffalograss fingerprint studies.
Protein Changes in Peach Seeds during Chilling Are Not Associated with Breaking Dormancy
Authors: Mahhou Ahmed , Dennis Frank G.
Published: January 2019

Siberian C peach (Prunus persica L.) seeds were stratified at 5 and 20C. DWs and soluble protein content remained constant regardless of stratification temperature and duration. Seed extracts subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a decrease in the intensity of nine polypeptides in the cotyledons of seeds held at 5C during weeks 5 through 8, coinciding with an increase in germination capacity. These changes were confined to cotyledons held at 5C, and were observed only when the seeds were able to germinate. The effects of stratification and the imbibition degree on changes in the protein content of seeds of two additional peach biotypes (`Farouki' and `Maloussi') were also evaluated. Germination of fully imbibed seeds at 20C increased steadily as stratification time at 5C increased. Partially imbibed seeds (25 % or 50% of full imbibition) did not germinate regardless of stratification time. However, when these seeds were soaked in water after stratification, their germination paralleled that of fully imbibed seeds. Thus, dormancy was broken, even though the seeds could not germinate. Changes in protein profiles in fully imbibed seeds confirmed those previously reported for Siberian C seeds. Similar changes occurred in cotyledons of partially imbibed seeds during stratification at 5C, but at a slower rate. Those changes were, however, delayed by partial imbibition, whereas germination capacity (ability to germinate when fully imbibed) was not. Changes in cotyledon protein profiles were not affected by removing the embryonic axis before stratification, a result indicating that such changes are not controlled by the axis. Gibberellic acid (GA3 induced 35 % to 40% germination of nonchilled seeds. It hastened the loss of protein band intensity in `Farouki' but not in `Maloussi'. However, GA3-treated seeds germinated before any visible changes occurred in protein profiles. We conclude that the effects of chilling on breaking dormancy are independent of its effects on the protein changes observed in this study.
Separating the Effects of Low Temperature, Ripening, and Light on Loss of Scald Susceptibility in Apples before Harvest
Authors: Barden Cynthia L. , Bramlage William J.
Published: January 2019

`Cortland' and `Delicious' apples (Malus domestics Borkh.) were exposed to an increasing number of hours below 10C before sequential harvests in each of 3 years. In separate experiments, `Cortland' apples were a) sprayed with ethephon to induce ripening at moderate temperatures and b) bagged in late August to produce ripening at low light intensities. Scald development was determined after 4 to 5 months of storage at 0C. Significant negative relationships with scald development occurred for hours below 10C, harvest date, and ripening indexes at harvest; however, the regressions with percentage scald were stronger for hours below 10C than for either harvest date or ripening. When ethephon-induced ripening occurred in the absence of low temperature, scald development decreased only slightly. Bagging fruit significantly delayed the loss of scald susceptibility with increasing hours below 10C. We conclude that low temperature was most responsible for rapid, substantial loss of scald susceptibility, and that light and ripening were secondary factors in this loss, interacting with the effects of temperature. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).
Copper Compounds Influence in Vitro Rooting of Birch Microcuttings
Authors: Arnold Michael A. , Lineberger R. Daniel , Struve Daniel K.
Published: January 2019

The effects of woody plant medium (WPM) with various formulations and concentrations of Cu+2 on in vitro rooting and subsequent shoot growth of microcuttings of a Betu pubescens × papyrzfera (birch) clone were monitored for 28 days. Adventitious root initiation and elongation were reduced in magnitude and slowed in development by moderate to high Cu (as CuSO4·5H2O) concentrations, with near zero root regeneration occurring at 157 μm Cu. Shoot growth was also inhibited by 157 μM Cu as cupric sulfate. Copper-toxicity symptoms (senescent leaves, necrotic stems, and bulbous and stunted roots) were significantly increased by moderate to high levels (≥ 79 μm) of Cu as cupric sulfate. Microcuttings responded differently to Cu+2 applied as cupric chloride (CuCl2·2H2O). Root initiation, root elongation, and root branching were increased by moderate concentrations of Cu as cupric chloride. Shoot growth was slightly stimulated by cupric chloride at moderate levels. No significant increase in Cu-toxicity symptoms was observed at concentrations up to 157 μm Cu as cupric chloride. Cupric acetate [Cu(CH3 COO);H2O] and cupric carbonate [CuCO3·Cu(OH)2] produced more severe Cu-toxicity symptoms than cupric sulfate. Root regeneration and shoot growth were inhibited and increased Cu-toxicity symptoms were apparent even with low concentrations (39 μm) of Cu as cupric acetate or cupric carbonate. There was little or no effect on root regeneration when the Cu+2 in cupric sulfate was replaced by different cations, i.e., magnesium sulfate (MgSO4·7H2O), calcium sulfate (CaSO4·2H2O), and sulfuric acid (H2SO4), a result suggesting that the observed responses could be attributed to the Cu+2 concentration. Changes in media pH did not correspond to Cu-toxicity symptoms or alterations in root or shoot growth by the Cu compounds.