bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Cadmium Concentration in Lettuce
Authors: Thomas Gene M. , Harrison Helen C.
Published: August 2022

Parental, F1, F2, and F3 generations were used to determine the inheritance of Cd concentration in lettuce (Lactuca sativa L.). Three plant introductions—PI 278080, PI 140398, and PI 169493—were parents for two crosses—PI 278080 × PI 140398 and PI 169493 × PI 278080. Data from the F2 and F3 generations did not fit simple Mendelian models. Broad sense heritability estimates for the two crosses, calculated from parental and F2 variances, were 0.38 and 0.29, respectively. Narrow sense estimates, calculated by the standard-unit regression analyses of F3 family means on F2 parents, were 0.05 and 0.30, respectively. Low, nonsignificant correlations were obtained between Cd concentration and dry weight of tissue samples in both F2 and F3 generations, indicating that selection for low concentration should not affect yield.
Pressure-induced Water Fluxes Through Root Systems of Sour Orange Seedlings
Authors: Swietlik Dariusz
Published: August 2022

Studies were conducted to compare responses of pressure- and transpiration-induced water fluxes (Jv) through root systems of sour orange (Citrus aurantium L.) (SO) seedlings and to quantify the apoplastic component of fluxes in the both systems. Roots excised from water-cultured SO seedlings were sealed in a nutrient solution-filled pressure chamber and pressurized at 0.5 MPa with air, N2, or CO2. Changing the pressurizing gas from air to N2 or CO2 reduced Jv, but the response to CO2 was more pronounced than to N2. The fluxes recovered when N2 and CO2 were in turn replaced by air. Transpiration of water-culture-grown intact SO seedlings responded similarly to changes in gasses bubbled through the nutrient solution. The Jv in excised root systems was decreased at elevated salt concentration in the root medium, a phenomenon commonly observed in intact plants. Root conductance taken from the slopes of the linear portion of pressure/flux curves was lower at low than high salt levels. The apoplastic water fluxes through pressurized roots and intact SO seedlings was quantified using trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate. The increased proportion of the apoplastic component in pressure-, compared to transpiration-induced, fluxes indicates that root pressurization opens one or more new avenues for water transport that are not operative in a transpiring seedling. Steady-state flow rates through the roots pressurized at 0.5 MPa were attained within ≈3 hr.
Physiological Responses of Cabbage to Incipient Copper Toxicity
Authors: Rousos Penelope A. , Harrison Helen C. , Steffen Kenneth L.
Published: August 2022

Three-week-old seedlings of the cabbage (Brassica oleracea L. Capitata group) cultivars Wisconsin All Seasons and Globe King were exposed for 3 weeks to Cu2+ concentrations ranging from 1.2 to 2.5 mg Cu2+/liter. Plants were harvested after 14, 16, 19, or 22 days of exposure. During Cu2+ treatment, shoots appeared healthy, but roots turned golden, with increased lateral branching and tip browning. Cultivars responded identically for all characteristics measured. Root Cu concentrations were >3000 μg·g−1 or 300 times the control after Cu2+ treatment. Shoot Cu concentrations (13 μg·g−1), while significantly higher than the control, were not above critical values associated with yield reductions. The high root Cu concentrations were not associated with lower shoot or root yields. The initial symptoms of Cu2+ toxicity in the first fully expanded leaves were elevated leaf Cu concentrations and lower total chlorophyll and chlorophyll a:b ratios. There was no effect on leaf fresh weight per unit area, transpiration, respiration, net photosynthesis, or apparent photosynthetic quantum yields.
ALMOPOL: A Cross-pollination and Nut Set Simulation Model for Almond
Authors: DeGrandi-Hoffman Gloria , Roth Stephan A. , Loper Gerald M.
Published: August 2022

ALMOPOL is an interactive computer-based model that simulates the interactions of weather, bloom phenology, blossom quality, and honey bee foraging behavior that culminate in almond [Prunus dulcis (Mill) D. A. Webb] nut set. ALMOPOL enables users to enter orchard conditions, colonies per hectare, and foragers per colony. Information concerning honey bee foraging behaviors and blossom quality (i.e., a blossom's probability of setting a nut if cross-pollinated) can also be entered interactively into the program. Hence, nut set estimates are specific for a given set of weather, orchard, bee behavior, and blossom quality conditions. A description of the logic and data used in ALMOPOL's construction is included.
Grapefruit Leaf and Fruit Growth in Response to Drip, Microsprinkler, and Overhead Sprinkler Irrigation
Authors: Zekri Mongi , Parsons Lawrence R.
Published: August 2022

Fruit and vegetative growth of 21-year-old grapefruit (Citrus paradisi Macf.) trees on well-drained sandy soil was studied in central Florida. Drip, microsprinkler, and overhead sprinkler irrigation was compared at two levels of irrigation (150 and 450 mm·year−1). Significant differences in leaf area, fruit size, fruit growth, new flush growth, and canopy area were found with different irrigation systems applying similar amounts of water. Growth was improved by irrigation even in a year of high rainfall (1410 mm). With mature trees, drip systems promoted the least growth, while overhead sprinkler systems promoted the most. Leaf fresh and dry weights and individual leaf areas in the overhead sprinkler treatments were 40% to 50% greater than in the drip or nonirrigated treatments, while specific leaf weight and leaf water content per unit dry weight were similar for all treatments. Final fruit size and tree canopy area were 9% to 20% greater in the overhead sprinkler treatments than in the corresponding drip or nonirrigated treatments. Responses to microsprinklers were generally intermediate between the overhead sprinkler and the drip treatments. Because of the low soil area coverage, applying water at the higher rate with the drip system did not improve growth as well as the overhead system at the lower rate. With mature grapefruit trees under central Florida conditions, systems providing greater soil area coverage gave better leaf and fruit growth than systems providing less soil coverage.
Nitrogen Fertilization x Genotype Interactions Influence Bermudagrass Turf Quality Characteristics
Authors: McCaslin Bobby D. , Hughes Michael R. , Baltensperger Arden A.
Published: August 2022

A field experiment was conducted to determine if the turf quality of bermudagrass (Cynodon dactylon L. Pers.) was influenced by an interaction of genotype and nitrogen fertilization. The currently recommended level for maintenance of adequate quality in New Mexico bermudagrass turf is 48 kg N/ha per month during the growing season, the highest rate used in the study. The response of 10 bermudagrass genotypes, ‘Common’, ‘FB 49’, ‘FB 119’, ‘FB 133’, ‘N-7’, ‘NM-B1’, ‘Ormond’, ‘Santa Ana’, ‘Tifgreen’, and ‘Texturf 10’ were evaluated at N levels of 0, 16, 33 and 48 kg N/ha per month during the growing season. Color, density, and clipping yield responses of the genotypes differed for the four N fertility Ievels.‘Texturf 10’ had the highest overall ranking at 48 kg N/ha per month and ‘Ormond’ had the highest ranking at 32 and 16 kg N/ha per month. Thus, cultivar selection must be considered in arriving at precision N fertilization of bermudagrass turf.
Predicting Firmness Changes of ‘Rome’ Apples in Refrigerated Storage
Authors: Ingle Morris , Morris J.C.
Published: August 2022

The softening rates of ‘Rome’ apples (Malus domestica Borkh.) from 10 West Virginia orchards stored at two temperatures were compared in 1974, 1976, and 1978. The rate of softening at 20°C declined with time after harvest, and delaying harvest reduced the rate of softening at 20° but had little effect on softening at 0°. Site had little effect on rate of softening. In two of the three years, the rate of softening at 0° was found to be correlated with firmness at harvest and softening at 20°. Regression analysis provided formulas that can be used to predict softening rate in refrigerated air storage at 0° from firmness data at harvest.
The Relationship Among Root Growth, Shoot Growth, and Fruit Growth of Peach
Authors: Williamson Jeffrey G. , Coston Donald C.
Published: August 2022

The number, length, and elongation rate of white roots were related to vegetative and reproductive growth of young own-rooted ‘Redhaven’ peach trees from June 1985 until Oct. 1986. Root growth of fruiting and nonfruiting trees were similar, except for a period of 3 to 4 weeks each year either during the final stage of fruit growth or immediately after harvest. During these periods, cropping reduced white root length per tree in both years, and total root growth per tree and number of growing root tips in 1986. Number of elongating root tips was correlated with total root elongation and was a better indicator of total root elongation than was mean root elongation rate of individual root tips.
Growth, Leaf Mineral Nutrition, and Leaf Water Status of Mature Apple Trees Subjected to Various Crop Loads and Soil Water Conditions
Authors: Erf Jeff A. , Proctor John T.A.
Published: August 2022

Mature fruiting and defruited ‘McIntosh’/M.26 apple (Malus domestica Borkh.) trees were exposed to natural rainfall or to no rainfall with the use of under-canopy tent-like covers. With covers present, fruit diameter tended to be less and, on one occasion, soluble solids concentration and fruit firmness increased. Trunk growth was reduced more by fruit than by covers. Trunk growth of fruiting trees did not respond to covers, whereas trunk growth of defruited trees was reduced by covers. Fruit load and reduced soil water content did not affect terminal shoot length. In one experiment, specific leaf weight (SLW) was less for fruiting trees than for defruited trees. Fruiting increased foliar N, P, Ca, and Mg and decreased K concentration. On a leaf-area basis, K was again lower in cropping trees while other nutrients remained mostly unchanged. With tent covers, trees generally had less foliar N, P, and K based on either concentration or amount per unit of leaf area. Leaf water potential was lower for trees with fruit and tended to be lower for trees with tent covers. Leaf stomatal conductance was higher for fruiting trees than for defruited trees and higher for trees without tent covers than for trees with tent covers.
Turfgrass Wear as Affected by Golf Car Tire Design and Traffic Patterns
Authors: Carrow R. N. , Johnson B. J.
Published: August 2022

Turfgrass wear tests were conducted at Griffin, Ga. in 1985 and 1986 on ‘Tifway’ bermudagrass (Cynodon dactylon × C. transvaalensis) using several golf car tire designs (tread configurations, radial or non-radial), golf cars, and traffic patterns. Wear damage to bermudagrass in all studies was assessed by visual turf quality, color, verdure, and leaf bruising. Golf car traffic caused significant wear damage regardless of golf car, tire design, or traffic pattern. Damage increased with frequency of trips over the site and with moderately sharp turns. Differences in wear injury between the tire designs did occur, but were minor in most instances. These differences could not be explained by tread pattern alone, since similar designs gave different degrees of wear. Whether the tire was radial or not did not influence turfgrass wear. Golf car type exhibited a minor effect on bermudagrass wear. Management alternatives to minimize turfgrass wear should concentrate on distributing traffic and avoiding sharp turns, while selection of pneumatic tire design or golf car is of minor relative importance.
Cell Wall Changes in Juice Vesicles Associated with “Section Drying” in Stored Late-harvested Grapefruit
Authors: Burns Jacqueline K. , Achor Diann S.
Published: August 2022

Normal and collapsed juice vesicles were removed from stored late-harvested grapefruit segments (Citrus paradisi Macf. cv. Marsh) and the cell wall anatomy of epidermal and internal parenchyma was compared with light, scanning electron, and transmission electron microscopy. Normal juice vesicles were turgid and elongate, and epidermal cells and internal parenchyma were intact. Collapsed juice vesicles appeared flattened, and internal parenchyma were compressed. Cell wall thickening occurred in internal parenchyma and single or clustered epidermal cells of collapsed vesicles. Cell walls of the same cells in normal vesicles were thin. Epidermal and internal parenchyma cell walls of collapsed vesicles were 10 to 50 to 10 to 20 times the thickness, respectively, of corresponding normal cell walls. Lignin was detected in thickened cell walls of epidermal and internal parenchyma of collapsed vesicles. The results suggest that cell wall synthesis in vesicles is a symptom of section drying in grapefruit.
Combining Ability Estimates for Muskmelon Tolerance to Myrothecium roridum and Its Toxic Metabolite, Roridin E
Authors: Kuti Joseph O. , Ng Timothy J
Published: August 2022

Five parental cultivars of muskmelon (Cucumis melo L.) and 16 F1 hybrids, including six reciprocals, were evaluated in a diallel design for reaction to inoculations with Myrothecium roridum and its phytotoxic metabolite roridin E using a detached leaf screening test. Analyses of variance revealed genetic variability for tolerance to the fungus and to the toxin; the correlation coefficient between inoculations with the pathogen and the toxin was 0.94. Disease and toxin tolerance were associated with highly significant general combining ability (GCA) effects, but specific combining ability were significant only for inoculations involving the pathogen. The GCA component accounted for 95.8% of the genotypic variation for pathogen tolerance and 99.3% for toxin tolerance. Reciprocal effects were not present in either set of inoculations.
Use of Rank Indexing for Comparative Evaluation of All-male and Other Hybrid Types in Asparagus
Authors: Corriols Lucette , Doré Claire
Published: August 2022

Numerous asparagus (Asparagus officinalis L.) hybrids have been developed worldwide during the past 20 years. Most are clonal hybrids. The French (INRA) breeding program has successively introduced double, clonal, three-way all-male, and F1 (mixed or all-male) hybrids. Because these hybrids are evaluated at different locations during different years, a composite comparison of all cultivars is not feasible. A ranking index has been developed to make useful the huge volume of heterogeneous data that has been accumulated from the many trials during the past 10 years. This index is based for each hybrid on 2 years of comparative harvest data at four locations from about 40 hybrids and check cultivars at each location and each year. Using these rank indexes, the different types of hybrids can be compared one with another and with foreign hybrids. These indexes show that 1) all-male F1 and three-way hybrids tend to have high total yield and earliness; 2) F1 mixed hybrids are likely to have relatively large spear diameter; 3) double, clonal, and foreign hybrids produce the most attractive spears; 4) the general superiority of all-male hybrids is confirmed; 5) the four characters that are the major breeding objectives—early yield, high total yield, large spear size, and attractive spear appearance—are difficult, but not impossible, to combine into one hybrid. The indexes also show that, in spite of general trends, individual hybrids outstanding in all characteristics can be found in each type of hybrid.
Genotypic Variability in the Frequency of Plant Regeneration from Leaf Protoplasts of Four Brassica spp. and of Raphanus sativus
Authors: Jourdan Pablo S. , Earle Elizabeth D.
Published: August 2022

More than 65 different genotypes, including cultivars and inbred lines, from five cruciferous species (Brassica oleracea L., B. campestris L., B. napus L., B. juncea L., and Raphanus sativus L.) were tested for their in vitro response of leaf protoplasts. Protoplasts were cultured in three liquid media and the resulting colonies were placed on seven test regeneration media. Significant differences among the species were found in plating efficiency in the frequency of shoot regeneration. Two broad response groups were identified: 1) Cultivars from B. oleracea and B. napus—these generally yielded protoplasts that were able to divide, form colonies at high frequencies, and regenerate shoots at variable frequencies; and 2) cultivars of the other species evaluated, which typically exhibited low plating efficiencies and little, if any, shoot regeneration. Evaluation for the effect of the cytoplasmic constitution of a few B. oleracea breeding lines on in vitro performance indicated that protoplasts carrying the Ogura (R1) male-sterile cytoplasm regenerated shoots at slightly lower frequencies than the corresponding alloplasmic-fertile lines. Genotypes exhibiting high frequency of shoot formation in one medium also had efficient shoot regeneration in other media as well, while genotypes with low shoot regeneration responded consistently in the different media used. This consistency in response indicates that genotype plays a critical role in determining the success of leaf protoplast culture in the crucifers.
Growth of Chrysanthemum Using an Irrigation System Controlled by Soil Moisture Tension
Authors: Lieth J. H. , Burger D. W.
Published: August 2022

Chrysanthemum × morifolium Ramat. cv. Polaris plants were grown in containers using an irrigation system based either on time (5 min/day) or on soil moisture tensions of −1.5, −3.5, −7.5, and −15 kPa. Soil moisture tensions of −7.5 or −15 kPa caused significant reductions over the time-based treatment in fresh and dry weights of leaves, stems, and inflorescences and total leaf area, but had no influence on inflorescence diameter or cropping time. Stem length was reduced in those plants exposed to the two higher tensions; however, the resulting cut flowers were still long enough to satisfy commercial demands. The amount of water applied in tension-based treatments was 8% to 24% that applied in the time-based treatment. The −1.5- and −3.5-kPa treatments were best suited for minimizing water use while maintaining high crop productivity.
Supplementary Lighting and Rooting of Three Cultivars of Small Rhododendrons
Authors: French Christopher J. , Alsbury James
Published: August 2022

Night-break lighting using low irradiance incandescent lamps (INC) from 2000 to 0400 hr stimulated rooting of Rhododendron ‘Thomwilliams’ (R. thomsonii × R. williamsianum), R. ‘Pink Bountiful’ (R. williamsianum × ‘Linswegeanum’), and R. ‘Sonata’ (R. ‘Purple Splendour’ × R. dicroanthum) when applied during spring propagation (February to June). INC stimulated rooting of ‘Thomwilliams’ and ‘Sonata’, but had no effect on ‘Pink Bountiful’ in the fall (September to January). Supplementary irradiance during the day from high-pressure sodium lamps (HPS) had little effect on rooting in spring. In the fall, HPS stimulated rooting of ‘Pink Bountiful’ and ‘Sonata’, but had no effect on ‘Thomwilliams’. For all cultivars, INC was less effective in stimulating rooting when applied with HPS. A night break of 8 hr was more effective than one of 4 hr in stimulating rooting of ‘Thomwilliams’. INC stimulated initial rooting and did not increase root growth.
Growing Green Ash and Red Oak in CuCO3-treated Containers Increases Root Regeneration and Shoot Growth Following Transplant
Authors: Arnold Michael A. , Struve Daniel K.
Published: August 2022

Control of green ash (Fraxinus pennsylvanica Marsh.) and red oak (Quercus rubra L.) root growth in containers treated with CuCO3 and its effects on root regeneration following transplant were studied. Root elongation was controlled by applying 100 g CuCO3/liter of flat-white exterior acrylic latex paint to the interior surfaces of plastic containers. Plants grown in CuCO3-treated containers did not require root-pruning, whereas root-pruning was required to correct root deformations of plants grown in untreated containers. Root pruning removed up to 37% of root dry weight. When plants grown in CuCO3-treated containers were transplanted to 45.6-liter containers, root dry weight beyond the original root ball was greater than that of root-pruned seedlings transplanted from untreated containers. Seedlings transplanted from CuCO3-treated containers to field plots in July, August, or September showed enhanced shoot growth for two growing seasons compared with root-pruned control seedlings. Seedlings transplanted from CuCO3-treated containers appeared to suffer less stress than root-pruned control seedlings transplanted on the same date. Green ash seedlings transplanted in July had greater shoot growth than those transplanted in August and September over two growing seasons.
Pretransplant Treatments of N and P Influence Growth and Elemental Accumulation in Tomato Seedlings
Authors: Widders Irvin E.
Published: August 2022

Tomato (Lycopersicon esculentum Mill.) seedlings, cultured under a moderately low mineral nutrient regime, were fertilized with 4 to 28 mm N and 0.5 to 8 mm P solutions for up to 10 days before transplanting into the field. The high N solution drenches (16 and 28 mm N) promoted accelerated seedling growth, higher relative growth rates during the initial 5 days after field setting, and an increased net accumulation of N and P in the shoot following transplanting into the field. Pretransplant treatments with P did not result in a shoot growth response. The total P concentrations and contents in shoot tissues, however, were significantly higher in the seedlings treated with 4 or 8 mm P than in those receiving 0.5 mm P. Since the rates of P uptake and accumulation in the shoot relative to shoot biomass were enhanced by both the N and P pretransplant treatments, root initiation and growth may have been stimulated.
Inheritance and Isozyme Diversity for GPI and PGM among Grape Cultivars
Authors: Parfitt Dan E. , Arulsekar S.
Published: August 2022

Leaf isozymes of 145 cultivars of grapes (Vitis vinifera L. and Vitis spp.) were separated via starch gel electrophoresis. They could be separated into 52 groups using glucosephosphate isomerase (GPI) and phosphoglucomutase (PGM) isozymes. Twenty-four cultivars had unique combinations of isozyme patterns. Two loci, Gpi-2 and Pgm-2, were identified and shown to be simply inherited with multiple alleles at each locus. The mean heterozygosity for the two loci (Gpi-2 and Pgm-2) among all the cultivars was 57.5%, indicating a high level of genetic variability among these cultivars. Indirect evidence for expressed linked lethal alleles was demonstrated by the missing classes in Gpi-2 and Pgm-2 segregation ratios (1:2:0 ratios) in several selfed progeny families. Chemical name used: methyl[1-(methylethyl)-1H-benzimidazol-2-y]-carbamate (benomyl).
Delayed Light Emission as a Means of Predicting Papaya Susceptibility to Fruit Fly Infestation
Authors: Forbus W. R. , Chan T.
Published: August 2022

Papayas (Carica papaya L.) at seven stages of maturity were harvested in Hawaii and evaluated for differences in intensity of delayed light emission (DLE) and Hunter ‘b’ values. There was a high correlation (r = −0.92) between DLE intensity and Hunter ‘b’ values for freshly harvested papayas at seven stages of maturity. DLE has a high potential as a rapid screening technique for detecting papays that are ripe enough to be susceptible to fruit fly infestation.
Rowcover Material and Time of Application and Removal Affect Ripening and Yield of Strawberries
Authors: Pritts Marvin P. , Worden Kathleen A. , Eames-Sheavly Marcia
Published: August 2022

Effects of time of application and removal of straw, clear polyethylene, black polyethylene, polypropylene, and polypropylene–polyamid rowcovers were measured for ‘Earliglow’ and ‘Allstar’ strawberries (Fragaria × ananassa Duch.). There was no consistent effect of date of autumn application on yield or fruit size for the polypropylene cover. All winter-applied rowcovers resulted in improved yields relative to uncovered plots, although this difference was not always significant. When applied during early spring, opaque materials reduced yields up to 46% and delayed fruiting as much as 3 days, while some translucent materials enhanced yields as much as 94% and accelerated harvest by 8 days compared to uncovered strawberries. Covering with translucent materials during both winter and spring had even stronger positive effects, with ‘Earliglow’ being more responsive. With translucent rowcovers, the time of removal had a greater effect on production and fruit size than rowcover type. Optimal removal dates differed for rowcover type and cultivar. For a short period of time in early spring, rowcovers apparently provide an environment favorable for flower development.
Modeling Row Cover Effects on Microclimate and Yield: II. Thermal Model and Simulations
Authors: Albright L. D. , Wolfe D. , Novak S.
Published: August 2022

An analytical model is described that predicts air and soil temperatures under row tunnels used for early season microclimate modification for field grown vegetables and fruits. The model is time dependent and based on simultaneous solutions of thermal radiation and thermal energy balances for each component of the thermal system. The model's adequacy was tested by comparing its predictions to field data. Reasonable agreement was found considering the approximations used to determine values of required thermal parameters. Sensitivity analyses are presented to demonstrate uses of the model, and the significance of the more important thermal parameters.
Analysis of the Response of Net Photosynthesis of Rose Leaves of Varying Ages to Photosynthetically Active Radiation and Temperature
Authors: Pasian C. C. , Lieth J. H.
Published: August 2022

‘Cara Mia’ rose (Rosa hybrida L.) leaf net photosynthesis rates were measured at four leaf temperatures over a range of irradiance levels. With the four leaf ages measured, a non-rectangular hyperbola with physiologically meaningful parameters was found to adequately represent the photosynthetically active radiation (PAR) responses. Maximal net photosynthetic rates exhibited a convex pattern with temperature with an optimum between 30 and 37C. The PAR compensation and saturation points both increased with temperature.
Phyllotaxy and Stage of Leaf and Fruit Development Influence Initiation and Direction of Carbohydrate Export from Sour Cherry Leaves
Authors: Kappes Ewald M. , Flore James A.
Published: August 2022

The influence of phyllotaxy and stage of leaf and fruit development on the initiation and direction of carbohydrate (CH2O) export from sour cherry (Prunus cerasus L.) leaves was investigated during two different seasons. One-year-old ‘Montmorency’ sour cherry trees on ‘Mahaleb’ rootstock were pruned to a single shoot, the seventh and 10th leaf (from the base) were pulsed with 14CO2, and labeled carbon products were located after 24 hr using autoradiography. In 1983, gross export (EG) from the seventh and 10th leaf was initiated when the area of the seventh leaf reached 8.5 cm2 (27% expansion) and when that of the 10th leaf reached 14 to 21 cm2 (48% to 72% expansion), respectively. EG was generally initiated later in 1985 than in 1983, for the seventh leaf later than 26 cm2 (47% expansion) and for the 10th leaf at 36 cm2 (78% expansion). Leaf size was greater at full expansion in 1985 than in 1983. On defoliated shoots, the 10th leaf (54 ± 16 cm2 full expansion) started export between 24 and 28 cm2 (44% to 52% expansion), whereas control leaves on nondefoliated shoots started export at 36 cm2 (78% expansion). We suggest that, after a leaf has developed the potential for phloem loading, the onset of CH2O export is a function of the CH2O availability in the plant at the time of leaf expansion. Translocation paths followed closely the orthostichy of the exporting leaf. Fruit effects on the direction of translocation were studied in 2-year-old trees. During stages I and III of fruit development, leaves closest to the base showed basipetal translocation only. All leaves during stage II and leaves distal to the midpoint of the shoot during stages I and III showed bidirectional translocation to the shoot apex and the fruits.
Characterization of Isozyme Variability in Apricots
Authors: Byrne David H. , Littleton Thomas G.
Published: August 2022

Seven enzyme systems were examined in 69 apricot [Prunus armeniaca L. and P. mandshurica (Maxim.) Koehne] clones. Three enzymes (6-phosphogluconate dehydrogenase, phosphoglucose isomerase, and phosphoglucomutase) were polymorphic at five loci. Only seven clones were characterized uniquely by their isozyme phenotypes and 56% fell into two of the 15 phenotypic groups found. Isozyme variability in apricot was greater than in peach, but less than that reported in plum or almond.
Phenotypic Recurrent Selection and Heritability Estimates for Total Dissolved Solids and Sugar Type in Carrot
Authors: Stommel John R. , Simon Philipp W.
Published: August 2022

Five cycles of phenotypic recurrent selection for total dissolved solids and sugar type (reducing vs. nonreducing) were performed on four carrot (Daucus carota L.) populations of common background. The populations contained high or low percentage of total dissolved solids (HTDS and LTDS, respectively) with high or low levels of reducing sugar (HRS and LRS, respectively). Effective selection for total dissolved solids (TDS) and sugar type was indicated by significant gains over five cycles of selection. TDS decreased in LTDS/HRS and LTDS/LRS populations by 21.9% and 15.9%, respectively. Corresponding increases of 22.4% and 28.2% were observed in HTDS/HRS and HTDS/LRS populations. Mean reducing sugar levels in HRS roots after five cycles of selection were limited to 2.0% of root fresh weight; sucrose was the primary storage carbohydrate. Reducing sugars were not detected in LRS roots. Mean total sugar levels in the HTDS and LTDS populations were 7.1% and 3.1% of root fresh weight, respectively. Realized heritability estimates ranged from 0.40 to 0.45 for the four populations. The onset of flowering was markedly delayed in plants of the two HTDS populations after five cycles of selection.
Inbreeding, Coancestry, and Founding Clones of Japanese-type Plums of California and the Southeastern United States
Authors: Byrne David H.
Published: August 2022

The mean inbreeding and coancestry coefficients of Japanese-type plums grown in California and the southeastern United States were one-half or less of those calculated for peach. The three most important founding clones for the major California cultivars were ‘Santa Rosa’, ‘Eldorado’, and ‘Gaviota’; for the plums of the southeastern United States they were ‘Methley’, ‘Santa Rosa’, and ‘Mariposa’. The species background of both groups of plums was ≈50% P. salicina, although the sources of P. salicina differed between groups. For the California cultivars, the other half was composed of P. simonii and P. americana, whereas, for the southeastern group, the major contributing species was P. cerasifera, with lesser contributions from P. simonii, P. americana, P. angustifolia, and P. munsoniana.
Optimizing Somatic Embryo Production in Mango
Authors: DeWald Stephen G. , Litz Richard E. , Moore Gloria A.
Published: August 2022

Medium components and characteristics that affect the growth of embryogenic mango (Mangifera indica L.) nucellar cultures and production of somatic embryos in vitro were studied. These included the role of complex organic supplements, basal medium formulations, solidifying agents, and liquid vs. solid media. Growth of embryogenic cultures in suspension was more efficient than on solid medium; however, subculture onto solid medium was essential for high-frequency production of morphologically normal somatic embryos, and Gelrite was more effective in this respect than Difco Bacto-agar. Modified B-5 basal medium was better for maintenance of cultures and for production of morphologically normal somatic embryos than either Murashige and Skoog or Woody Plant Medium. Sucrose concentrations at 5% to 6% were optimal for somatic embryo production, and also increased the frequency of recovery of normally differentiated early heart-shaped somatic embryos. Coconut water (20%, v/v) enhanced somatic embryo production by 18%; other complex organic addenda alone or in combination with coconut water were either ineffective (casein hydrolysate) or highly inhibitory (yeast extract) in comparison with basal medium alone.
Photosynthetic Photon Flux Influences Macroelement Weight and Leaf Dry Weight per Unit of Leaf Area in Prune Tree Canopies
Authors: Weinbaum S. A. , Southwick S. M. , Shackel K. A. , Muraoka T. T. , Krueger W. , Yeager J. T.
Published: August 2022

The relationship between canopy position and foliage concentrations of several phloem-mobile and -immobile essential nutrients was determined over a 20-fold range of average incident photosynthetic photon flux (PPF) (50 to 1000 μmol·s−1·m−2) in 7-year-old prune (Prunus domestica L., syn. ‘Prune d’Agen’) tree canopies. Mineral weight per unit of leaf area (LA) increased with increasing PPF within the canopy according to the relationship N > Ca > Mg > K > P. Dry weight per leaf area (DW/LA) increased 3-fold over the range of light exposures sampled. Leaf nutrient concentration expressed as percent dry matter (DM) did not vary with PPF. Both DW/LA and leaf N/LA appear to integrate the light microenvironment at the canopy coordinates of leaves sampled and may be correlated with photosynthetic capacity. Thus, these parameters may have diagnostic value in orchard management and crop production.
Validation of a Computer Model for a Single-truss Tomato Cropping System
Authors: McAvoy Richard J. , Janes Harry W. , Giacomelli Gene A. , Giniger Michael S.
Published: August 2022

The accuracy of a computer planning model for the management of a single-truss tomato (Lycopersicon esculentum Mill.) production system was tested in the greenhouse. The model was used to generate a production schedule for 24 successive crops during a 15-month study. The time, in days, required for an emerging seedling to reach anthesis and the total fresh weight fruit yield were predicted for each of the 24 crops by the planning model. Correlation analysis, used to compare the expected crop response (i.e., data generated by the planning model) to the actual crop response, indicated that both the number of days from emergence to anthesis and fresh weight fruit yield were accurately forecast, r2 = 0.76 and 0.83, respectively. More important, the cropping schedule that was generated by the planning model successfully produced a continuous harvest of tomatoes from sequential crops.
Effects of Plant Density on Growth and Biomass Partitioning in Pickling Cucumbers
Authors: Widders Irvin E. , Price Hugh C.
Published: August 2022

Pickling cucumbers (Cucumis sativus L. cvs. Tamor and Castlepik) were direct-seeded at six plant densities (in thousands, 44, 77, 97, 121, 152, 194) using two between-row spacings (71 and 36 cm) and three within-row spacings (29, 14, and 11 cm between plants). Compared with the 29 cm within-row spacing, the 11- and 14-cm spacings resulted in significantly lower total above-ground plant dry weights, growth rates, and total leaf areas for both cultivars as early as 21 to 27 days after planting. The between-row spacing effects on plant growth were similar, but were of a lower magnitude and appeared later in plant development than for the within-row spacing effects. Leaf lamina and fruit tissue exhibited the largest reduction in tissue dry weights per plant compared to stem and petiole tissue when plant density was increased from ≈4.5 to 20 plants/m−2 (45,000 to 200,000 plants/ha). Lower fruit productivity per plant at higher plant densities resulted from fewer fruit set per plant and lower fruit : shoot ratios. Unit leaf rate (g dry weight/day per g of lamina dry weight) was not affected by plant spacing during the fruit development period. Increased densities resulted in significantly higher leaf area indexes, and vegetative and total above-ground dry weights/m−2. Total fruit yield with a single harvest did not increase above ≈77,000 plants/ha for both cultivars. A high correlation (r = 0.877) between leaf lamina dry weight and fruit growth rate indicates that net photosynthetic capacity might be limiting fruit productive potential in pickling cucumbers.
Paclobutrazol—A Plant Growth Retardant for Increasing Yield and Fruit Quality in Muskmelon
Authors: Nerson Haim , Cohen Ron , Edelstein Menahem , Burger Yosef
Published: August 2022

The effects of paclobutrazol (cultar, PP333) on yield and fruit quality of muskmelon (Cucumis melo L. var. reticulatus Naud. cv. Galia) were examined in a series of field experiments, in the spring at Newe Ya’ar (northern Israel) and in autumn at Biq’at HaYarden (lower Jordan Valley, eastern Israel). In the spring experiments, paclobutrazol applied at 2 and 4 mg·liter−1 as a drench to the media-mix of muskmelon transplants increased total fruit yield 15% to 20% at various plant populations and in combination with ethephon and/or chlorflurenol, but tended to decrease the early yield. Yield increase was due to an increase in fruit weight rather than number. Paclobutrazol, in general, tended to improve marketable yield, yield concentration, and netting index. In the autumn experiment, paclobutrazol was applied at 250 mg·liter−1 as a spray from flowering through fruit maturation and compared with benzyladenine (BA), and N, P, and K fertilization. Paclobutrazol reduced early leaf-yellowing symptoms, but was not as effective as BA. Paclobutrazol in the autumn experiment did not affect yield or yield components, but soluble solids content was significantly increased and keeping-quality was unaffected. Chemical names used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-l ethanol (paclobutrazol); (2-chloroethyl)phosphonic acid (ethephon); (methyl-2-chloro-9-hydroxyfluorene-(9)-carboxylate) (chlorflurenol); benzyladenine (BA).
Cuticular Properties and Postharvest Calcium Applications Influence Cracking of Sweet Cherries
Authors: Glenn Gregory M. , Poovaiah B. W.
Published: August 2022

The influence of stomata, the stylar scar, cuticular fractures, and Ca2+ on susceptibility of ‘Bing’ sweet cherry fruit (Prunus avium L.) to water injury was studied. Water injury was first detected as an increase in cell turgor. Water penetration caused separation of the cuticle from the epidermal cell wall. Swelling in the epidermal cell wall region resulted in cuticular fracturing that generally preceded fruit cracking. Uncracked fruit that had cuticular fractures softened rapidly. Stomata were sparsely distributed on the fruit surface and were often fixed in an open or partially open position. Water injury was not visible at stomata even when injury occurred adjacent to the stomatal region. Initial signs of injury were commonly visible near the stylar scar. Histochemical studies revealed that the surface of the stylar scar was devoid of a cuticle covering and was rich in insoluble carbohydrates. Greater penetration of solute containing 45Ca2+ occurred at the stylar scar. Fine fractures in the cuticle surface were observed in fruit at harvest time in 1985 and 1986. Cherry fruit with cuticular fractures had a higher water absorption rate than unfractured fruit. In immersion tests, Ca2+ reduced cherry cracking. EGTA increased fruit cracking; this increase was negated by adding Ca2+. Neither Ca2+ nor EGTA affected the water absorption rate of the fruit. EGTA decreased the cracking threshold of the fruit, while Ca2+ increased it. Soluble pectin content of the immersion solution rose with increasing incubation times. EGTA increased while Ca2+ markedly decreased soluble pectin concentration in the immersion solution. Histochemical studies indicated a breakdown of the cell wall structure in the epidermal region of water-injured fruit. Autoradiographs of fruit immersed in a solution containing 45Ca2+ showed the epidermal region to be the site of Ca2+ action in altering fruit cracking. Chemical name used: Ethyleneglycol-bis-(β-aminoethyl ether) N,N,N,N-tetraacetic acid (EGTA)
Modeling Peach Fruit Growth and Carbohydrate Requirements: Reevaluation of the Double-sigmoid Growth Pattern
Authors: DeJong T. M. , Goudriaan J.
Published: August 2022

Seasonal patterns of fruit growth were measured on early and late-maturing peach (Prunus persica L. Batsch) cultivars (‘June Lady’ and ‘O’Henry’, respectively). Seasonal relative growth rates of fruit dry matter accumulation were calculated. The relationships between fruit relative growth rates and respiration were used to develop a quantitative carbon budget model of peach fruit growth and sink activity. The resulting model indicates that the double-sigmoid growth pattern of peach fruits involves only two physiologically distinct phases of sink activity instead of the three stages that are traditionally recognized. The traditional stage II of fruit growth is apparently a function of the timing of the shift between these two physiological phases of sink activity.
Relationship between Trypsin-inhibitor Activity and Water-soluble Protein and Cumulative Rainfall in Sweet Potatoes
Authors: Lin Yaw-Huei
Published: August 2022

Variance analysis and variance components showed that total, heat-stable (HS) and heat-labile (HL) trypsin-inhibitor activity (TIA) of sweet potato [Ipomoea batatas (L.) Lam. 2n = 6x = 90] roots, expressed as units or specific units, were significantly different for monthly planting dates and cultivars. There were also significant differences among planting dates and cultivars for water-soluble (ws) protein content. Patterns of variation of total, HS, and HL TLA over 12 planting dates were similar and also similar to those of water-soluble protein content for four cultivars when TLA was expressed as units instead of specific units. When 12 values of TIA (units; total HS and HL) were plotted against water-soluble protein content, a positive correlation was found for all four cultivars. However, the positive correlation disappeared or weakened when TIA was evaluated as specific units. Stepwise removal of variables in multiple linear regression of cumulative rainfall, cumulative temperature, and TIA showed that there was a large negative correlation of the natural logarithm of TIA (units; total, HS and HL) on cumulative rainfall, suggesting that TIA may vary in response to drought of sweet potatoes.
Comparison of Hydathode Structure in Micropropagated Plantlets and Greenhouse-grown ‘Queen Elizabeth’ Rose Plants
Authors: Donnelly D. J. , Skelton F. E.
Published: August 2022

Foliar anatomical comparisons were made between in vitro-grown plantlets and greenhouse-grown plants of ‘Queen Elizabeth’ rose (Rosa sp.) using scanning and light microscopy. Each acuminate leaf apex and marginal serration had a terminal hydathode region composed of a glandular tip and a subterminal, adaxial group of sunken water pores. Leaf apices of greenhouse-grown plants had up to 35 water pores per hydathode, while cultured plantlets had < 20. Hydathodes of leaf serrations had up to 10 water pores in both sample groups. Water pores and stomata of plantlet leaves were open, while those of greenhouse-grown plants had smaller apertures or were completely closed. Internally, hydathodes were delimited by a bundle sheath extending below the vascular tissues and approaching the adaxial epidermis on each side of the water pore zone. Files of tracheary elements extended various distances into the leaf teeth. Small, irregularly shaped parenchyma cells (epithem) abutted on the xylem parenchyma cells, filling the space between the files of tracheary elements and the adaxial epidermis. The hydathodes of plantlet leaves were smaller with fewer water pores and reduced epithem than those of greenhouse-grown plants. Ex vitro guttation probably occurs as a result of increased water potential and high relative humidity when plantlets are transferred from culture to soil.
Use of FDR 2n Pollen to Transfer Resistance to Root-knot Nematodes into Cultivated 4 × Potatoes
Authors: Iwanaga M. , Jatala P. , Ortiz R. , Guevara E.
Published: August 2022

Resistance to root-knot nematodes (RKN; Meloidogyne spp.) found in wild potato species (Solanum sparsipilum and S. chacoense) was transferred into an advanced 2x breeding population. Resistant genotypes were crossed with cultivated 2x clones and simultaneous selection applied for resistance, horticultural traits, and production of first-division restitution 2n pollen. Experiments were conducted to determine if resistant 2x clones with 2n pollen production would efficiently transmit their resistance to 4x progenies by means of 4x × 2x crosses. More than 2000 seedlings from 40 families derived from 2x × 2x, 4x × 2x, and 4x × 4x crosses were evaluated for resistance. It was found that: 1) 18% of the progeny derived from 4x (susceptible) × 2x (resistant) crosses were resistant to RKN. Thus, the 2n pollen producing 2x clones are valuable genetic material for the production of RKN-resistant 4x progenies; 2) The existence of resistant 4x progenies with either S. tuberosum spp. tuberosum or S. demissum cytoplasm indicated that S. sparsipilum cytoplasm was not essential for the expression of the resistance genes.
Direct Shoot Regeneration from Strawberry Leaf Disks
Authors: Nehra Narender S. , Stushnoff Cecil , Kartha K.K.
Published: August 2022

An efficient and reproducible method of direct shoot regeneration from leaf disks in strawberry (Fragaria × ananassa cv. Redcoat) has been developed. The influence of hormone concentration, light intensity, orientation of leaf disk, and age of explant source on shoot regeneration was examined. Regeneration of leaf disks reached 94%, with an average of 13 shoots per leaf disk, within 8 weeks when MS salts and B-5 vitamins medium supplemented with 10 μm each of BA and IAA were used. The adventitious shoot meristems initially arose from epidermal or sub-epidermal cells at the periphery of the leaf disks and later from surface cells of the newly regenerated meristems. Shoot regeneration did not depend on light, but low light intensity (12.5 μmol·s−1 m−2) greatly enhanced regeneration. The leaf disks obtained from 30-day-old greenhouse plants and from young runner plants produced shoots at higher frequency than those obtained from 1-year-old plants. Regeneration frequency was higher when the adaxial surface of leaf disks was kept in contact with the medium surface. Shoot regeneration also occurred in nine other genotypes at varying frequencies, but with an intervening short callus phase, except in ‘Veestar’. The technique has potential application for rapid propagation and genetic manipulation of strawberries.
Plant Regeneration from Callus-derived Protoplasts of Asparagus
Authors: Elmer Wade H. , Ball Terry , Volokita Michal , Stephens Christine T. , Sink Kenneth C.
Published: August 2022

Donor callus cells for protoplasts were initiated from mature plants of four selected crowns of asparagus (Asparagus officinalis L.) by placing spear slices on solidified Murashige and Skoog salts and vitamins medium (MS) with 3% sucrose + (in mg·liter−1): 1.0 NAA + 1.2 2,4-D + 0.9 BA or 1.0 kinetin + 2.5 2,4-D. Callus derived from these explants was further subcultured on the same medium. Optimum protoplast yields were enzymatically obtained from such calluses 10 to 20 days after subculture. Of the isolated protoplasts 65% to 75% were viable, and when plated in modified Kao and Michayluk medium at 5 × 104 or 105/ml densities, had 6.5% and 7.3% plating efficiencies, respectively. Protoplast isolations had 0.81% to 1.4% cells present that were not observed subsequently to undergo division. Only the cells of protoplasts of ‘Jersey Giant crown No. 8’ divided during 8 weeks to form microcalluses. After transfer and culture for an additional 4 to 5 weeks on solidified MS + (in mg·liter−1): 0.1 NAA + 1.0 kinetin, shoots regenerated at 28% efficiency. Shoots were rooted at 50% efficiency on solidified MS + (in mg·liter−1): 0.3 NAA + 0.7 kinetin + 2.1 ancymidol + 4% sucrose. The rooted plants were readily transferred to the greenhouse. Chemical names used: 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), N-(phenylmethyl)-1H-purin-6-amine (BA), N-(2-furanylmethyl)-1H-purin-6-amine (kinetin), α-cyclopropyl-α-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol).