bluuebunny/crossref_metadata_2025 huggingface dataset:
Root Growth and Water Status of Trickle-irrigated Cucumber and Tomato
Authors: Randall Harold C. , Locascio Salvadore J.
Published: August 2022

Two trickle irrigation experiments were conducted during two successive years with cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) grown on a coarse-textured soil in ground beds in a greenhouse. Several trickle irrigation design characteristics (emitter spacings of 15, 30, and 45 cm and one or two laterals per crop row) and water management variables (2 or 8 liters/hr per emitter water application rates and water quantities equivalent to 0.25- and 0.50-times pan evaporation) were examined for their effect on soil water content, root distribution, and plant water status. Water application rates did not influence root density distributions or plant water status; however, the 8 liters·hr−1 water application rate resulted in higher water content in the top 20 cm of soil than the lower application rate. The higher water quantity resulted in higher soil water content, higher root density, and improved plant water status than with the lower quantity. Mature plants had root systems that were well-adapted to the different soil water distributions. Only the amount of water applied influenced the water status of mature cucumber plants and cucumber fruit yields.
A Degree Day Model for Predicting the Emergence of Swamp Dodder in Cranberry
Authors: Bewick Thomas A. , Binning Larry K. , Yandell Brian
Published: August 2022

A simple model that predicts the onset of swamp dodder (Cuscuta gronovii Willd. ex R. & S. # CVCGR) emergence was developed. The use of growing degree days (GDD) with low-temperature thresholds (LTT) of 3.3° or 0°C had a better fit as a predictor for the beginning of emergence than either air temperature or soil temperature at a depth of 30 mm alone. This model can be used to time preemergence herbicide applications to coincide with the period of maximum dodder sensitivity, thereby increasing herbicide efficacy.
Growth Analysis of Field-grown Strawberry Genotypes Differing in Yield: I. The Matted Row System
Authors: Strik Bernadine C. , Proctor John T.A.
Published: August 2022

Seven field-grown strawberry genotypes (Fragaria × ananassa Duch.) were grown in matted rows and harvested weekly from early spring until the end of harvest. An increase in plant dry weight through the season was due mainly to inflorescence and leaf development. Genotypes differed in the progression of the natural log of plant dry weight and leaf area over time, relative growth rate, absolute growth rate, leaf area ratio, and unit leaf rate. Genotypes differed in growth variables through the season, but only crown dry weight during the fruiting period was correlated with yield among genotypes. Total plant dry weight was not correlated with yield, indicating the importance of the percent dry matter partitioned to the inflorescence.
The Consequences of Inbreeding on Fertility in Vaccinium corymbosum L.
Authors: Krebs Stephen L. , Hancock James F.
Published: August 2022

Seed counts from self- and cross-pollinated highbush blueberry cultivars suggested that fertility in both mating systems is under similar genetic control. Viable seed set following selfing and outcrossing was inversely correlated with zygotic levels of inbreeding, and percentage of seed abortion in both crosses showed a positive association with zygotic F values. Among six genotypes, cross- and self-fertility were highly correlated. Fluorescent microscopy revealed no differences in the frequency of self and foreign pollen tube growth into ovules. Variation in self- and cross-fertility among these cultivars was attributed to differences in zygotic levels of homozygosity and cumulative expression of recessive mutations that promote seed abortion.
Orchard Soil Management Systems Influence Rainfall Infiltration
Authors: Glenn D. Michael , Welker William V.
Published: August 2022

The purpose of this study was to assess the effect of four soil management systems: herbicide strip (H), cultivated strip (C), mowed sod (MS), and killed sod strip (KS) on rainfall infiltration in two young peach [Prunus persica (L.) Batsch] orchards. Soil water content (0- to 0.90-m depth) was measured immediately before a rainfall event and then as soon as possible after the rain. During the first growing season, MS captured more rainfall than KS, H, or C in the spring and summer months. In the fall, when soil water levels were reduced, all of the soil management systems were equally effective in reducing rainfall runoff. During the second and third growing seasons, the KS system often captured as much rainfall as MS and more than H and C, when killed sod residue covered 50% or more of the surface. When < 10% soil cover remained in the KS treatment, it was no more effective in reducing runoff than the H or C treatments. Growth and yield parameters were lowest in the MS due to sod interference. KS generally provided greater growth and yield than the C and H.
Inheritance of Stem Elongation Tendency in Determinate Forms of Common Bean
Authors: Detongnon Jean , Baggett James R.
Published: August 2022

The inheritance of internode length and plant height in bush forms of common bean (Phaseolus vulgaris L.) was studied in crosses of E6211, a bush bean of ‘Blue Lake’ type with elongated internodes, with three lines having a more compact growth habit. Apparent dominance of long internode expressed by the F1 and backcrosses of one cross, E6211 × K19, in both greenhouse and field, was not supported by the F2, which showed additive gene action. For both internode length and plant height, the trend was for slight dominance of either the tall or short parental type in the F1, with the F2 showing more additivity or greater dominance of the short parent than the F1 or backcrosses. Field results supported additive inheritance more than did greenhouse results.
Studies of Three New Genes, Linkage, and Epistasis in Lettuce
Authors: Ryder Edward J.
Published: August 2022

Three new lettuce (Lactuca sativa L.) genes were described and named: shiny green (Sgsg), salmon (Sasa), and apple green (Agag). Plump involucre and male sterile are linked, with p = 0.345. Plump involucre and Early flowering are linked closely, with p approaching zero. Twenty-five gene pairs tested for linkage were independently inherited. In achene color, the order of recessive epistasis is white > yellow > brown. The double-recessive combination vivicd-2cd-2 (virescent and chlorophyll deficient) is phenotypically virescent and partially lethal.
Responses of ‘Bartlett’ Pear to Withholding Irrigation, Regulated Deficit Irrigation, and Tree Spacing
Authors: Mitchell Peter D. , van den Ende B. , Jerie P.H. , Chalmers D.J.
Published: August 2022

Fruit yield was increased, summer pruning decreased, and water saved when regulated deficit irrigation (RDI) and withholding irrigation (WI) were used over 5 years to manage mature ‘Bartlett’ pear (Pyrus communis L.) trees planted at three levels of within-row spacing (0.5, 0.75, and 1.0 m) and trained to a Tatura trellis. Three levels of irrigation, 23%, 46%, and 92% replacement of evaporation from the planting square (Eps), were compared during the RDI period. Weight of summer prunings was positively and linearly related to level of irrigation in each year, including a relatively wet year. When compared between years, the degree of this response on the dried treatment was positively and significantly related to net evaporation (evaporation – rainfall) recorded during the period of rapid shoot growth. Fruit number also tended to be greater on the 23% and 46% Eps treatments in all years. Cumulative yield over 10 years of cropping did not differ between tree spacing, although fruit size was larger at the 1-m spacing. High yields were obtained at all levels of tree spacing. Yield and tree growth responded most to RDI for the 0.5-m-spaced trees.
Hydrology of Horticultural Substrates: I. Mathematical Models for Moisture Characteristics of Horticultural Container Media
Authors: Milks Robert R. , Fonteno William C. , Larson Roy A.
Published: August 2022

Moisture retention data were collected for five porous materials: soil, phenolic foam, and three combinations of commonly used media components. Two mathematical functions were evaluated for their ability to describe the water content–soil moisture relationship. A cubic polynomial function with linear parameters previously used on container media was compared to a closed-form nonlinear parameter model developed to describe water conductivity in mineral soils. In most tests for precision, adequacy, accuracy, and validation, the nonlinear function was superior to the simpler power series. The nonlinear function provides an excellent tool for describing the water content for media with widely varying physical properties.
Permeability of Flexible Polymer Films Used to Wrap Citrus Fruit to the Fumigants Ethylene Dibromide and Methyl Bromide
Authors: Houck Laurie G. , Mackey Bruce E.
Published: August 2022

Permeability to the postharvest fumigants ethylene dibromide (EDB) and methyl bromide (MB) varied among 10 plastic films tested on grapefruit (EDB) and oranges (MB). Permeability was determined by comparing fumigant residue levels in fumigated film-wrapped citrus fruit and fumigated nonwrapped fruit. Some films restricted passage of the fumigants to the fruit, and residue levels in fruit wrapped with these films were lower than in fumigated, nonwrapped fruit. Residue levels in fruit wrapped with other films were equal to those in fumigated, nonwrapped fruit and these films were judged to be highly permeable to the fumigants. EDB and MB residues were slightly higher in fruit wrapped with three of the films than those in nonwrapped fruit, indicating that these films were slightly less permeable to EDB and MB than to other films tested, and also that desorption of the fumigants from the fruit during post-fumigation aeration was slowed by these three films. The permeability of flexible polymer films to fumigants such as EDB and MB should be a prime consideration when selecting films for wrapping citrus fruit in quarantine situations.
Yield and Quality of ‘Redblush’ Grapefruit on Twelve Rootstocks
Authors: Fallahi Esmaeil , Moon John W. , Rodney D. Ross
Published: August 2022

Effects of 12 rootstocks on yield and quality of ‘Redblush’ grapefruit (Citrus paradisi Macf.) were measured under the arid climate of southwestern Arizona. Trees on ‘Palestine’ sweet lime (C. aurantifolia L.) and ‘Volkamer’ lemon (C. limon Burm. f.) produced high cumulative yield, but small fruit. Trees on macrophylla (Alemow) (C. macrophylla) produced higher yields 5 years after planting, and had significantly higher mean yield efficiency than trees on other rootstocks; trees on ‘Cleopatra’ mandarin (C. reticulata Blanco.) and ‘Taiwanica’ (C. taiwanica) had a relatively lower production 9 years after planting. Fruit of trees on ‘Carrizo’ and ‘Troyer’ citranges [Poncirus trifoliata (L.) Raf. × C. sinensis (L.) Osbeck] were largest. Trees on ‘Savage’ citrange (P. trifoliata × C. sinensis) had lowest yield, thinnest peel, and highest levels of total soluble solids content and soluble solids : acid ratio. Fruit of trees on ‘Swingle’ citrumelo or C.P.B. 4475 (C. paradisi × P. trifoliata) rootstock consistently had higher percentage acid than those on other rootstocks. Considering yield and/or various quality factors, ‘Volkamer’ lemon, rough lemon (C. limon Burm. f.), ‘Palestine’ sweet lime, ‘Oklawaha’ sour orange (C. aurantium L.) and, particularly, ‘Carrizo’ citrange, are suitable for ‘Redblush’ grapefruit in the arid regions of the southwestern United States. ‘Savage’ citrange, ‘Ichang’ pummelo (C. ichangensis hyb.), and ‘Swingle’ were poor-yielding rootstocks for ‘Redblush’ grapefruit and are thus undesirable for planting under the standard spacing (7 × 7 m) of this experiment. ‘Savage’ and ‘Swingle’ might be good choices at higher densities because they increased yield efficiency and quality.
Propagation and Subsequent Growth of Rhododendron Cuttings: Varied Response to CO2 Enrichment and Supplementary Lighting
Authors: French Christopher J.
Published: August 2022

CO2 mist (1100 μl CO2/liter) during fall propagation inhibited rooting of Rhododendron ‘Anna Rose Whitney’ (R. griersonianum × ‘Countess of Derby’) and had no effect on R. ‘Vulcan’ (‘Mars’ × R. griersonianum), R. ‘Unique’ (R. campylocarpum hybrid), R. ‘Anah Krushke’ (R. ponticum seedling), or R. ‘Pink Bountiful’ (R. williamsianum × ‘Linswegeanum’). Supplementary lighting from high-pressure sodium lamps (HPS) for 16 hr/day (0400 to 2000 hr) had no effect on rooting of any cultivar. There was an interaction between CO2 mist and HPS exposure on rooting in R. ‘Floriade’ (‘Britannia’ hybrid). CO2 mist inhibited and HPS stimulated shoot development during propagation. CO2 mist during propagation inhibited subsequent development of ‘Anna Rose Whitney’ and ‘Vulcan’. HPS during propagation inhibited subsequent growth of ‘Floriade’ and ‘Vulcan’. CO2 enrichment of stock plants prior to propagation did not affect rooting of R. ‘Sonata’, whereas CO2 mist during propagation was inhibitory. In ‘Anna Rose Whitney’, there was an interaction between CO2 enrichment before and during propagation. Application of supplementary HPS for 16 hr/day following propagation stimulated subsequent growth of both cultivars. CO2 mist during spring propagation stimulated rooting of ‘Pink Bountiful’ and ‘Vulcan’ and had no effect on R. ‘Matador’ (R. griersonianum × strigillosum), R. ‘Martha Isaacson’ (R. occidentale × Ostbo seedling No. 70), or R. ‘Elizabeth’ (R. forestii var repens × griersonianum). Supplementary HPS had no effect on rooting. A low irradiance night break treatment from incandescent lamps (2000 to 0400 hr) had no effect on rooting of ‘Vulcan’. There was an interaction between night break lighting and CO2 mist on rooting in ‘Unique’. CO2 mist and HPS during spring propagation had minor effects on subsequent growth of ‘Matador’, ‘Martha Isaacson’, ‘Pink Bountiful’, and ‘Elizabeth’. CO2 mist and supplementary HPS have little value in production of Rhododendron.
Water Quantity and Time of N and K Application for Trickle-irrigated Tomatoes
Authors: Locascio S. J. , Olson S. M. , Rhoads F. M.
Published: August 2022

Tomatoes (Lycopersicon esculentum Mill.) were grown during two seasons at two locations on fine sands and fine sandy loam soils to study the influence of water quantity, frequency of water application, and timing of N and K application for polyethylene-mulched, trickle-irrigated fresh-market tomatoes. Water quantities were 0.50 and 1.0 times pan evaporation applied one or three times daily. Nitrogen and K were applied 100% preplant or 40% applied preplant and 60% applied with trickle irrigation. Higher tomato leaf tissue N and K concentrations in one of the two seasons and higher fruit yields were obtained with 0.5 than with 1.0 time pan water evaporation on a fine sand at Gainesville, Fla. On a fine sandy loam soil at Quincy, fruit yields were higher in a relatively dry season with the higher water quantity and not influenced by the water quantity applied in the second relatively wet season. The number of daily water applications (one vs. three) at both locations had no effect on N and K uptake or fruit yields. Time of N and K applications had no effect on early yields, but total yields were higher with split than all preplant-applied N and K on the fine sandy soil. Split applications of fertilizer resulted in greater yields of extra-large fruit at mid-season and of extra large and large fruit at late harvest than all preplant-applied fertilizer. On the fine sandy loam soil, time of fertilizer application had no effect on yield.
Sweet Corn Plant Responses to P and K in the Soil and to Band-applied Monoammonium Phosphate, Potassium Sulfate, and Magnesium Sulfate
Authors: Peck Nathan H. , MacDonald George E.
Published: August 2022

Responses of sweet corn plants (Zea mays L. var. rugosa cv. Jubilee) to levels of residual P and K in a fine sandy loam soil from previous broadcast applications of concentrated superphosphate (CSP) and potassium chloride (KCI) and to band-applied monoammonium phosphate (MAP), potassium sulfate (K2SO4), and magnesium sulfate (MgSO4) at planting were studied. Fourteen years after no applications of broadcast CSP or KCI fertilizers, responses of sweet corn plants to levels of residual P were greater than to residual K in the soil. Increasing the level of residual P in the soil increased dry weight per seedling from 1.5 to 7.7 g, fresh weight per ear from 278 to 358 g, the concentration of P from 2.9 to 4.6 mg·g−1 dry weight, but decreased K, Ca, and Zn in the leaves. Increasing the level of residual K in the soil did not affect the dry weight of the seedlings or the fresh weight of the ears, but increased the concentration of K from 16.7 to 28.1 mg·g−1 dry weight and decreased Ca and Mg in the leaves. Banded MAP, especially at low levels of residual P in the soil, increased the dry weight of the seedlings and the fresh weight of the ears. Banded K2SO4 did not affect the weight of the seedlings or ears, but increased the concentration of K and decreased Ca and, especially, Mg in the leaves. Banded MgSO4, with or without high residual K in the soil and/or banded K2SO4, did not affect weight of the seedlings or ears, but decreased the concentration of K and increased Mg in the leaves of the sweet corn plants.
Cytokinin and Soluble Carbohydrate Concentrations in Xylem Sap of Apple during Dormancy and Budbreak
Authors: Young Eric
Published: August 2022

Xylem sap from three apple (Malus domestica Borkh.) rootstocks was vacuum-extracted during and after artificial chilling and during forcing of chilled and unchilled trees. Sap was assayed for cytokinins by immunoassay and for soluble carbohydrates (sorbitol, glucose, fructose, and sucrose) by enzymatic assays. Xylem cytokinin increased after 10 days of forcing at 21/18C regardless of chilling treatment. Cytokinin levels decreased significantly as budbreak occurred in fully chilled trees, but not in unchilled trees with very little budbreak. Xylem sucrose, glucose, and fructose concentrations decreased upon exposure to 21/18C, then increased after 30 days in both chilled and unchilled trees. Sorbitol level remained low and unchanged throughout growth. Full chilling was not necessary in apple for adequate cytokinin and carbohydrates to be transported to the developing buds via the xylem stream. Sorbitol apparently is not used in carbohydrate transport from reserve, as it is in photosynthesis.
Germination and Seedling Growth of Perennial Ryegrasses in Soluble Salts
Authors: Horst Garald L. , Dunning Nancy B.
Published: August 2022

A laboratory experiment was conducted with seeds of perennial ryegrass (Lolium perenne L.) cultivars germinating and growing on floating mats in saline hydroponic solutions. This study was done to determine the relative intraspecific salt resistances of 48 perennial ryegrasses during germination and seedling growth in saline solutions. Total germination, germination rate, leaf blade length, root length, and total seedling fresh and dry weight were measured after 21 days. Test solutions prepared from deionized water and equal quantities of NaCl and CaCl2 by weight consisted of 11.6 (low), 19.5 (medium), and 23.5 dS·m−1 (high) salinity. Cultivars had highly significant total germination and germination rate responses to salt stress. Seedling growth responses as measured by blade and root length and weights were also significant. A hydroponic medium with a salt concentration of 23.4 dS·m−1 should provide a suitable stress level for screening ryegrass genotypes for improved germination and seedling salt resistance. At the high salinity level, cultivars that average less than a 50% reduction in growth parameters relative to high-yielding cultivars should be considered. Broad-sense heritability estimates indicate that seedling dry and fresh weight and germination rate would be valuable criteria for use in selection of perennial ryegrasses for salt resistance.
Stigma-Pollen Interactions in Pecan
Authors: Wetzstein Hazel Y. , Sparks Darrell
Published: August 2022

Early pollen-stigma responses were observed microscopically in controlled pollinations of pecan [Carya illinoensis (Wangenh) C. Koch]. Receptive stigmatic surfaces have rounded, basally attached projecting papillae with an irregularly patterned, noncopious exudate. Polarly flattened pollen, characteristic of grains at anthesis, becomes rounded and hydrated by 1 hr after pollination. Pollen tube emergence is visible within 3 hr of pollination, and extensive pollen tube growth on the stigma is apparent after 8 to 12 hr. Tube growth generally occurs along the stigmatic surface and between adjacent cells. Stigmatic cells collapse after pollen hydration and germination, with collapse extensive 24 hr after pollination. By 48 hr after pollination, stigmatic cells are flattened, and pollen grains and emerged pollen tubes have contents discharged with a similar collapse.
‘Riesling’ Grapes Respond to Cluster Thinning and Shoot Density Manipulation
Authors: Reynolds Andrew G.
Published: August 2022

Five-year-old ‘Riesling’ grape (Vitis vinifera) vines growing in the Okanagan Valley of British Columbia were subjected to three crop levels (full crop, two clusters per shoot, and one cluster per shoot) in combination with no shoot thinning or thinning to 24 shoots per meter of row. Reduction in crop level improved vine size and cane periderm formation slightly. Yield per vine was linearly related to crop level, but berry weight, berries per cluster, and cluster weight increased with decreasing crop level. °Brix and pH increased and titratable acidity decreased with reduction in crop level. Thinning to 24 shoots per meter of row provided some improvement in yield components and °Brix. Crop loads below 10 kg of fruit per kilogram of cane prunings are necessary to achieve adequate fruit maturity under Okanagan conditions.
Ethylene and Silver Thiosulfate Influence Opening of Cut Rose Flowers
Authors: Reid Michael S. , Evans Richard Y. , Dodge Linda L. , Mor Yoram
Published: August 2022

The presence of very low concentrations of ethylene had dramatic effects on the opening of cut flowers of rose (Rosa hybrida L.). Depending on cultivar, the rate of opening was unaffected (e.g., ‘Gold Rush’), accelerated (e.g., ‘Sterling Silver’), or inhibited (e.g., ‘Lovely Girl’). The Km for the inhibition of opening of ‘Lovely Girl’ by ethylene was 4 ppb. Flowers of some cultivars (e.g., ‘Royalty’) had an abnormal shape when opened in the presence of ethylene. The effects of exogenous ethylene could be overcome by pretreatment of the flowers with 0.5 μmol silver thiosulfate per stem. No phytotoxicity was observed in flowers treated with 2 μmol per stem. Examination of the kinetics of the ethylene/Ag+ interaction in inhibition of opening of ‘Lovely Girl’ flowers indicated that the Ag+/ethylene interaction was competitive.
Temperature and Temperature Preconditioning on Flux and Chemical Composition of Xylem Exudate from Muscadine Grapevines
Authors: Andersen P. C. , Brodbeck B. V.
Published: August 2022

Volume flux (Jv), solute flux (Js), and the chemical profile of xylem exudate from cut shoots of ‘Noble’ and ‘Welder’ muscadine grapevines [Vitis rotundifolia (Michx.)] were analyzed as a function of temperature and temperature preconditioning. The effects of short-term (i.e., 2-hr) temperature changes on Jv, xylem fluid osmotic potential (Ψs) and Js from bleeding ‘Noble’ grapevines were determined. The effects of 10 days of preconditioning temperature (4 to 8C or 22 to 28C) on ‘Noble’ and ‘Welder’ were monitored at 25C in relation to Jv, Ψs, Js and inorganic element, amino acid, organic acid, and sugar composition of xylem fluid. Short-term temperature changes induced marked increases in Jv (Q10 = 2.0) and Js but little alteration in Ψs. Temperature-preconditioning effects were cultivar-dependent. Js was enhanced ≈2-fold for both cultivars when preconditioned at 22 to 28C. The stimulation in Js of ‘Noble’ was a result of increased solute concentration (reduced Ψs); increased Js of ‘Welder’ was associated with increased Jv. We propose that the increase in Js with a concomitant increase in Jv of ‘Welder’ was due to a change in hydraulic conductance. Conversely, the increase in Js of ‘Noble’ was due to an increased solute concentration in cells surrounding the xylem vessels and/or to changes in membrane permeability to solutes. Temperature preconditioning had a substantial effect on inorganic ion, amino acid, organic acid, and sugar profile in xylem exudate of ‘Noble’, yet the chemical profile of ‘Welder’ was not altered. The physiological basis for this cultivar-dependent preconditioning response is discussed.
Surfactant-induced Ethylene Production by Leaf Tissue
Authors: Lownds N. K. , Bukovac M. J.
Published: August 2022

Ethylene evolution induced by nonionic (Triton X-100, Triton X-405, Tween 20, Ortho X-77 and Regulaid), anionic (Aerosol OT and Dupanol ME), and cationic (Arquad C-50 and Arquad 2C-75) surfactants was characterized using cowpea [Vigna unguiculata (L.) Walp. supsb. unguiculata ‘Dixielee’] seedlings. Representative surfactants of each ionogenic class induced ethylene evolution. Time course studies revealed an increased rate of ethylene evolution during the first 6 to 12 hr after treatment, followed by a slow decrease for the next 12 to 36 hr, and a return to control levels within 48 hr. Ethylene production induced by Triton X-100 increased with increasing concentration, while Tween 20 did not induce ethylene at concentrations up to 1.0%. Surfactants that promoted ethylene evolution also generally induced visible phytotoxicity. Phytotoxicity symptoms increased with increasing time after treatment. Surfactant-induced ethylene production and phytotoxicity were observed with corn (Zea mays L. ‘B73 × MO17’), wheat (Triticum aestivum L. ‘Hillsdale’), soybean (Glycine max Merr. ‘McCall’), apple (Malus domestica Borkh. ‘Golden Delicious’), and sour cherry (Prunus cerasus L. ‘Montmorency’). Tween 20, nonactive on cowpea, induced ethylene and phytotoxicity when applied to the abaxial surface of sour cherry leaves. Chemical names used: octyl-phenoxypoly(ethoxy)ethanol (Triton X-100 and X-405), polyoxyethylene sorbitan monolaurate (Tween 20), alkylaryl polyoxyethylene glycols/free fatty acids/isopropanol (Ortho X-77), polyoxyethylenepolypropoxypropanol alkyl 2-ethoxyethanol/dihydroxy-propane (Regulaid), diocytl sodium sulfosuccinate (Aerosol OT), sodium lauryl sulfate (Dupanol ME), monococo trimethyl ammonium chloride (Arquad C-50), dicoco dimethyl ammonium chloride (Arquad 2C-75).
Nitrogen Concentration and Photosynthetic Photon Flux in Greenhouse Tomato Production: II. Nitrate Reductase and Glutamine Synthetase
Authors: Larouche Régis , Vézina Louis-Philippe , Gosselin André
Published: August 2022

The activity of nitrate reductase (NR) and glutamine synthetase (GS) was followed during 4 weeks in various tissues of tomato plants (Lycopersicon esculentum Mill. cv. Vedettos) grown in growth chambers under two photosynthetic photon flux (PPF; 125 and 250 μmol·s−1·m−2, high-pressure sodium lamps) conditions for 18 hr and with four N fertilization regimes (5, 10, 15, and 20 meq·liter−1). In roots, NR increased with increased PPF but not with increasing N. Leaf NR activity was stimulated by increased PPF. Leaf NR increased over time in all treatments, but the highest values were obtained at lower N concentrations. Glutamine synthetase was stimulated by both light and N increases; its activity also increased throughout the 4 weeks of treatment. Nitrate reductase activity was highly correlated with the fruit fresh weight : leaf fresh weight ratio. On a mature tomato plant, NR activity was found mainly in leaves opposite developing fruits (sixth and seventh leaves), while GS activity was concentrated in the upper portion of the plant (second and third leaves).
A Gauge to Measure Mass Flow Rate of Sap in Stems and Trunks of Woody Plants
Authors: Steinberg Susan , van Bavel Cornelius H. M. , McFarland Marshall J.
Published: August 2022

A stem flow gauge designed for herbaceous plants was adapted for measuring the absolute mass flow rate of sap in large stems and trunks of woody plants. The method uses a steady-state heat balance method in which a constant, known amount of heat is supplied to a stem segment. The axial and radial conductive heat fluxes away from the heated segment are measured, as well as the rise in sap temperature. The device can be operated by commonly available dataloggers and does not require calibration. In a greenhouse experiment with a small tree, the sap mass flow rate, as measured by the the gauge, agreed with the measured transpiration rate within 4% when both were integrated over 24-hr periods or longer. Short term comparisons (≤4hr) were less accurate, due to the changes in water content of the tree above the gauge, which cause a lag between transpiration rate and sap flow rate. The dynamic response of the tree and gauge system to sudden changes in sap flow was ≈20 min under midday conditions. Other than the insertion of temperature-sensing thermocouples 2 mm into the trunk, the gauge components are non-invasive and do not disturb the tree physically or physiologically to a significant extent.
Developmental Control of Russet Spotting, Phenolic Enzymes, and IAA Oxidase in Cultivars of Iceberg Lettuce
Authors: Ke Dangyang , Saltveit Mikal E.
Published: August 2022

Leaf midrib tissue from six cultivars of iceberg lettuce (Lactuca sativa L.) was excised from 20- to 100-day-old plants and tested at 5C for russet spotting (RS) susceptibility under 10 μl ethylene/liter. There was no RS development in tissue excised from 20-day-old plants from any of the six cultivars. RS first developed in tissue from 50-day-old plants and tended to be more severe in tissue excised from older plants. ‘Winter Haven’ and ‘Salinas’ were most susceptible, while ‘Calmar’ was most resistant to RS; ‘Climax’, ‘El Toro’, and ‘Sea Green’ were moderately susceptible. Phenylalanine ammonia-lyase activity in the six cultivars at different developmental stages correlated with their degree of RS development. For ‘Winter Haven’, the increase in ionically bound POD and IAA oxidase activity, but not PPO activity, was associated with the increase in RS score during plant development. ‘Winter Haven’ tissue had much higher ionically bound peroxidase and IAA oxidase activities than ‘Calmar’ tissue from 100-day-old plants. Chemical names used: indole-3-acetic acid (IAA), phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO).
Leucostoma persoonii Tolerance and Cold Hardiness among Diverse Peach Genotypes
Authors: Chang L. S. , Iezzoni A. , Adams G. , Howell G. S.
Published: August 2022

Open-pollinated progeny from 15 peach (Prunus persica) cultivars, two peach × P. kansuensis hybrids, and one peach almond (P. amygdalus) hybrid were evaluated for their cold hardiness and for tolerance to Cytospora canker following artificial inoculation with Leucostoma persoonii. Winter hardiness was negatively correlated with canker necrotic length (r = −0.26**) and positively correlated with canker rating (r = 0.26**), as indicated by qualitative ratings. The half-sib families differed for canker necrotic length following fall inoculation, indicating that individuals with increased tolerance to L. persoonii canker could be selected from the population. Progeny from the cultivar Yennoh exhibited the shortest canker necrotic length following fall inoculation, and all the inoculated branches were visually healthy. ‘Yennoh’, a plant introduction from Russia, may have a higher tolerance to Leucostoma than has previously been found in U.S. germplasm.
Anatomical and Biochemical Factors Determining Ray Floret Color of Zinnia angustifolia, Z. elegans, and Their Interspecific Hybrids
Authors: Boyle Thomas H. , Stimart Dennis P.
Published: August 2022

Anatomical and phytochemical studies of Zinnia angustifolia HBK, Z. elegans Jacq., and their interspecific hybrids were initiated to define factors affecting ray floret color. Clones of Z. angustifolia with ivory, orange, or white ray florets, and Z. elegans lines with orange, pink, red, white, or yellow ray florets were crossed intraspecifically to produce S1 and F1 progeny. Interspecific hybrids were produced by crossing orange- or white-flowered Z. angustifolia clones (as ♀♀) with Z. elegans lines (as ♂♂). In both species and interspecific hybrids, pigments were present mainly in the upper epidermis, more dilute in the lower epidermis, and not observed in internal parenchyma. Variation in ray floret color in Z. elegans was primarily due to presence or absence of carotenoids in chromoplasts and anthocyanidins in vacuoles. Quantitative differences in the anthocyanidins pelargonidin and cyanidin were detected among Z. elegans lines; in vivo expression of anthocyanins was influenced by epidermal cell pH. Ray floret color in Z. angustifolia was due to presence or absence of two novel anthocyanidins and ivory-colored flavonoids, with no attributable effect of epidermal cell pH on anthocyanin expression. Carotenoids were not present in ray florets of Z. angustifolia × Z. elegans hybrids, regardless of whether carotenoids were expressed in the Z. elegans parent line. Presence or absence of the two novel anthocyanidins from Z. angustifolia and cyanidin from Z. elegans permitted unique combinations of floral pigments in interspecific hybrids not previously found in either species.
Agrobacterium-mediated Transformation of Peach Cells Derived from Mature Plants that were Propagated in Vitro
Authors: Hammerschlag A. , Owens L. D. , Smigocki A. C.
Published: August 2022

Stem explants of in vitro-propagated peach (Prunus persica L. Batsch.) cultivars Compact Redhaven, Jerseyqueen, Rio Oso Gem, and Suncrest and peach rootstock Nemaguard were infected with several strains of Agrobacterium tumefaciens. Tumor tissue was produced on all cultivars infected with strain tms328::Tn5, which carries a mutated octopine Ti plasmid pTiA6. The tumor tissues were cytokinin-independent and all tissues, except those on ‘Rio Oso Gem’, produced octopine. A DNA probe specific for the T-DNA region of the Ti plasmid hybridized to the DNA extracted from these tumors. No tumor tissue was produced in response to inoculation of the stem explants with the Ti-plasmidless strain A136 or with uninoculated controls. These results demonstrate the transformation of peach cells derived from mature plants and the potential for using A. tumefaciens to transfer economically important genes to peach.
Histology of Zygotic and Somatic Embryogenesis in Borage
Authors: Quinn James , Simon James E. , Janick Jules
Published: August 2022

Embryo sac formation in borage (Borago officinalis L.) was of monosporic, Polygonum type. Zygotic embryogenesis resembled the Piperad type (Myosotis Variation) without a suspensor after the four-cell stage with free nuclear endosperm. Cotyledons were initiated 4 days after pollination (DAP) and grew rapidly until 12 to 14 DAP, with seed maturity at 18 DAP. There were two patterns of in vitro somatic embryo development from embryogenic callus: 1) from single cells, which proceeded through typical zygotic embryo stages; or 2) from groups of cells that developed as a meristem. The advanced stages of somatic embryogenesis were characterized by abnormal cotyledon and hypocotyl morphology and incomplete apical development.
The Possible Use of the Crop Water Stress Index as an Indicator of Evapotranspiration Deficits and Yield Reductions in Sweet Corn
Authors: Braunworth William S. , Mack Harry J.
Published: August 2022

The crop water stress index (CWSI) may be useful for optimal irrigation timing. This preliminary study evaluates the relationships between the CWSI and evapotranspiration (ET) and yield. The CWSI was also characterized on an hourly basis. Once-daily CWSI measurements after full ground cover was established and hourly CWSI measurements on 4 days were made in sweet corn (Zea mays L. ‘Jubilee’) irrigation experiments in 1984 and 1985. The gradient of water applied included five irrigation levels established from 0% to 100%, with the 100% level intended to refill the root zone to field capacity, after 50% depletion of available water, at each irrigation. CWSI values, obtained hourly throughout the day, were highest between 1000 and 1700 hr. CWSI values tended to be higher in the less-irrigated plots (40% and less) than in those that received greater amounts of water (57% to 100% treatment levels). Seasonal average CWSI values (midday measurements) were closely related to the seasonal ET deficit (r2 ranged from 0.45 to 0.96), but there was not the expected 1:1 relationship of CWSI and ET deficit. The yield deficit of good, husked ears was also closely related to CWSI (r2 ranged from 0.82 to 0.93), but differences in these relationships between years and experiments indicate that CWSI measurements must be improved.
High-temperature Stress and Mitochondrial Activity of Harvested Mature-green Tomatoes
Authors: Inaba Makoto , Chachin Kazuo
Published: August 2022

Mature-green tomatoes (Lycopersicon esculentum M. cv. Sakata TVR) were stored at 5, 10, 15, 20, 25, 30, 35, or 40C. During storage, the respiration rate and C2H4 production were suppressed at 5, 10, and 35C. Tomato ripening and ethylene production were suppressed and injury was obvious at 40C. Mitochondrial oxidation of malate, succinate, α-ketoglutarate, and citrate were significantly suppressed at 30 and 35C. The respiratory control ratios and ADP:O ratios of 35C were consistently lower than those at 25C. Tomato mitochondria developed the cyanide-insensitive pathway of respiration with increased storage temperature, especially at 30 and 35C, and with extended storage time. The NAD+ -dependent malic enzyme increased at 35C, but malate dehydrogenase activity did not increase with ripening at 35C.
Light-mediated Inhibition of in Vitro Late Embryogeny of Ilex
Authors: Ferreira Alfredo G. , Hu Ching-yeh
Published: August 2022

An inhibitory effect of light on in vitro late embyogeny of I. aquifolium and I. opaca cv. Farage was observed. A negative log-linear correlation between the final embryo size and hours of continuous light during preincubation, at an intensity of 64 W·m−2, was established with I. aquifolium. It took ≈ 15 hr of pre-incubation light to result in 50% growth inhibition. Negative log-linear correlations between the final embryo lengths and light intensities were also observed for I. aquifolium and I. opaca. The rudimentary embryos of I. opaca were more sensitive to light inhibition than those of I. aquifolium. During incubation for 11 and 14 days with a 16-hr photoperiod, light intensities for 50% growth inhibition were ≈ 5 and 11 W·m−2 for I. opaca and I. aquifolium, respectively. Since growth inhibition by light could not be reversed by the presence of GA3 concentrations up to 1000 μm, some factor(s) other than the accumulation of abscisic acid or related compounds is probably responsible for such a phenomenon.
Free and Bound Residues of 2,4-D in ‘Marsh’ Grapefruit and ‘Washington’ Navel Orange Fruit
Authors: Erner Yair , Coggins Charles W.
Published: August 2022

Good preharvest fruit drop control toward the end of navel orange [Citrus sinensis (L.) Osbeck] and grapefruit (Citrus paradisi Macf.) harvest seasons in California may require higher than maximum label rates of 2,4-D. Therefore, residues from preharvest aqueous applications of 2,4-D made at 1.5 to 2 times higher than current label rates for preharvest fruit drop control were determined. In navel orange, the residue range found for free plus bound 2,4-D was 0.03 to 0.52 ppm in the flavedo and 0.05 to 0.14 ppm in the albedo. The free plus bound 2,4-D residue range found in grapefruit rind tissue was 0.11 to 0.22 ppm. Only trace amounts were found in pulp tissue of either cultivar. When pH was carefully controlled during each step of the fractionation procedure, recoveries of 2,4-D in excess of 83% were obtained. Residues found were considerably lower than established tolerances of 5 ppm in the United States and 2 ppm in some other countries. Thus, residues would permit higher application rates if needed and if label rates were increased. Chemical name used: 2,4-dichlorophenoxy acetic acid (2,4-D).
Organogenesis from Immature Pecan Embryonic Axes in Vitro
Authors: Yates I.E. , Wood B.W.
Published: August 2022

Immature embryos were excised during kernel development from fruits of the pecan [Carya illinoensis (Wangenh.) C. Koch] cultivars Desirable and Stuart. The cotyledons were removed and the main embryo axes were used as explants. Explants were cultured in vitro on media containing various levels of cytokinins and auxins. Morphogenesis in ‘Stuart’ preceded that of ‘Desirable’ by 1 to 2 weeks. In both cultivars, the percentage of embryo axes forming shoots only or both shoots and roots increased until ≈4 to 6 weeks before nut maturity, as judged by shuck dehiscence. After this time, developmental responses declined. Production of normal plants was highest on a medium containing IBA, BA, and kinetin at 0.5, 4.4, and 9.3 μM, respectively. Shoots only were obtained on a medium containing cytokinin without auxin and roots only on a medium containing auxin with no cytokinin. Axillary shoots elongated from embryo axes of both cultivars. This response was greatest on a medium containing cytokinin as the only hormone for ‘Desirable’, but with both auxin and cytokinin for ‘Stuart’. Chemical names: indole-3-butyric acid (IBA); N-(phenylmethyl)-1H purin-6-amine (BA); N-(2-furanylmethyl)-1H-purin-6-amine (kinetin).
Solution Depth Affects Root Morphology and Growth of Cucumber Plants Grown in Circulating Nutrient Solution
Authors: Chung Gap C. , Rowe Richard N. , Field Roger J.
Published: August 2022

Defruited cucumber (Cucumis sativus L.) plants were grown hydroponically for 28 days in containers with 4.5 liters of capacity, in which constant solution depths of 1, 5, 50, and 170 mm were maintained. The plants grown in the 1- and 5-mm-deep solutions grew more slowly than those in the deeper solutions. Both root and shoot growth were reduced at the shallow depths, but shoot growth was affected more than root growth. Thus, the shoot : root ratios were considerably smaller in the shallower than in the deeper solutions. The root systems in the shallower solutions, initially, were relatively more branched than in the deeper solutions. The shallow solutions caused the plants to allocate a higher proportion of their photosynthetic resources to the root at the expense of leaf growth. In the shallow solutions, a progressively higher proportion of this root growth became exposed above the solution, and, therefore, could not contribute to the absorption of water and nutrients. Control of solution depth may be a useful tool for controlling the vigor of the shoots of cucumber and the data presented may explain why growth problems have been experienced with this crop, particularly where a very thin film of nutrient is used, as in nutrient film technique.
Decay Control and Quality Maintenance after Moist Air Heat Treatment of Individually Plastic-wrapped Nectarines
Authors: Anthony Bryan R. , Phillips D.J. , Badr S. , Aharoni Yair
Published: August 2022

Moist air heat treatment at 52C for 15 min prevented decay in individually plastic-wrapped or naked nectarine [Prunus persica (L.) Batsch var. nectarina (Ait.) Maxim.] fruit puncture-inoculated with Monilinia fructicola (Wint.) Honey. Heat treatment for 5 or 10 min slowed decay development, but did not prevent it. In treatments where decay occurred, the wrap increased decay. Heat treatment tests at 52C for 15, 30, 45 min slowed softening and ethylene production of fruit. Wrapping alone reduced ethylene production 75% and respiration 12%, but did not significantly influence softening. The wrap reduced or eliminated undesirable skin browning associated with heat treatments.
Hormonal Basis for Low Light Intensity-induced Flower Bud Abscission of Pepper
Authors: Wien H.C. , Turner A.D. , Yang S.F.
Published: August 2022

A series of field and greenhouse experiments was conducted with three cultivars of bell pepper (Capsicum annuum L.) to determine the hormonal basis for flower bud and flower abscission as induced by low light intensity (LLI). Imposition of 80% shade for 6 days increased abscission of reproductive structures by 38% and resulted in an increase in bud ethylene production. Concomitantly, bud reducing sugars and sucrose decreased and these were negatively correlated with ethylene levels and those of its precursor, ACC. Infusion of ACC into the pedicel resulted in flower bud abscission within 48 hr. The results indicate that ethylene is the primary causal agent of pepper flower bud abscission. Production of auxin by the bud plays a role in prevention of abscission. The abscission of disbudded pedicels was prevented by infusion of NAA. Although the three cultivars had similar responses to ACC, they differed in the amount of abscission under stress, bud sugar levels, and the time of onset of ACC and ethylene production. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC); α-napthaleneacetic acid (NAA); (2-chloro-ethyl)phosphonic acid (ethephon).
Net Photosynthesis and Stomatal Conductance of Peach Seedlings and Cuttings in Response to Changes in Soil Water Potential
Authors: Harrison R.D. , Daniell J.W. , Cheshire J.M.
Published: August 2022

Greenhouse-grown peach [Prunus persica (L.) Batsch] seedlings and cuttings were drought-stressed by reducing soil water potential (ψsoil) from field capacity (FC) to permanent wilting point, (PWP). Mean ψsoil and leaf water potential (ψleaf) were correlated with measurements of stomatal conductance (gs), net photosynthetic (Pn) rate, and vapor pressure deficit (VPD). Decreasing Pn and gs trends were noted as ψsoil decreased. Photosynthetic rate and gs were significantly reduced at ψleaf more negative than −1.5 MPa. Values of Pn and gs were more highly correlated to ψleaf than ψsoil. A midday depression in Pn rates began 2 hr earlier and peak rates were at least 50% lower when ψsoil was more negative than −0.05 MPa. The correlation coefficient (r) between ψleaf and ψsoil and between gs and Pn rate at different ψsoil was above 0.70. The r values decreased as soil and plant water potential became more negative. Stomatal conductance peaked at optimal ψsoil (FC) 2 hr following sunrise. Photosynthetic rate peaked at a ψsoil around −0.05 MPa 4 hr after sunrise.
The Effect of Calcium on Respiration of Apples1
Authors: Faust Miklos , Shear C. B.
Published: August 2022

Respiration of apples was inversely related to Ca content of flesh. Respiration increased markedly if Ca concn was below 110 ppm. High N levels also increased respiration. High Ca successfully counteracted the N effect and kept the respiration at a low level. When N was supplied as ammonium, respiration was higher than when a similar quantity of N was supplied as nitrate. Calcium counteracted the increased respiration induced by ammonium-N. Low Ca fruit lost 30-70% of its capacity to synthetize proteins and nucleic acids as measured by the incorporation of labelled valine and uracil. Low-Ca fruit was also high in ethanol insoluble solids, the major portion of which was probably cellulose. The effect of Ca on respiration can explain the negative relation between certain disorders (internal breakdown and watercore) characterized by overmaturity and Ca content of fruit.