bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection of Sweet Potato For Tolerance to Aluminum Toxicity: Screening Procedures and Field Test
Authors: Sangalang J.B. , Bouwkamp J.C.
Published: August 2022

The effects of varying levels of Al on fibrous root growth variables of vine tip cuttings of sweet potato [Ipomoea batatas (L.) Lam] were tested in a quartz-sand medium in the greenhouse. A significant negative relationship between Al level and root growth was noted. Root weight was increased slightly on some clones at Al levels up to 250 μM. Aluminum levels > 500 μM considerably reduced root growth. Root lengths relative to the control were used in the screening of 379 sweet potato clones and in the preliminary identification of 60 tolerant and 55 sensitive clones. The tolerant clones had greater relative root length than the sensitive ones. In a field study, no significant differences in marketable root yield were noted between lime treatment (pH 5.4) and sulfur treatment (pH 4.2). The sulfur treatment, however, increased nonmarketable yield. The sensitive clones produced greater nonmarketable yield than the tolerant ones. A negative relationship between Al tolerance and yield in nonstress condition was indicated; tolerant clones generally yielded less than sensitive ones in nonstress field tests. Root lengths in the no-Al treatment in the greenhouse were significantly correlated with the marketable root yield and number in the limed field treatments.
Agrobacterium-mediated Gene Transfer in Papaya
Authors: Pang S.Z. , Sanford J.C.
Published: August 2022

The cocultivation method for transforming plant tissues in vitro with A. tumefaciens strains has been simplified and extended for use with leaf disks, stems, and petioles of Carica papaya L. These tissues have been transformed successfully with either pTiB6S3:pMON200 or pTiB6S3 with very high efficiency. Transformants were identified either by growth in hormone-free medium or by resistance to 300 μg·ml−1 of kanamycin. Putative transformants were confirmed on the basis of nopaline production.
Inhibitors as a Possible Basis for Grape Replant Problem
Authors: Brinker A.M. , Creasy L.L.
Published: August 2022

To determine whether grape (Vitis sp.) replant problem might be an example of autotoxicity, soil samples from fields that had or had not been replanted with grape cuttings were extracted with a neutral solution of ethylenediaminetetraacetic acid (EDTA) and by leaching with half-strength Hoagland's solution. Rooted grape cuttings growing in sand also were leached. Fractions of the leachates and extracts were assayed for toxicity using lettuce seedlings. Grape roots and replant soil yielded a toxic substance not present, or possibly present only at low levels, in non-replant soil. The replant soil extract inhibited phenylalanine ammonia-lyase activity in grape roots more than did the non-replant soil extract. The toxic substance in the replant soil extract was partially purified and a 1H nuclear magnetic resonance (NMR) spectrum taken, but the substance has not been identified. Thus, grape roots appear to be the source of at least one compound that is toxic to plants and accumulates in the soil in which grapes are grown.
Growth and Seasonal Partitioning of Dry Matter in Eight-year-old ‘Loring’ Peach Trees
Authors: Miller Anita Nina , Walsh Christopher S.
Published: August 2022

During the 1984 growing season, trees of ‘Loring’ peach (Prunus persica L. Batsch) on ‘Halford’ rootstocks were divided into the following components; fruit, leaves, shoots, 1-year wood, 2-year wood, frame, and roots. The sampling dates were coincident with key fruit and tree developmental stages: dormant, 15 days after full bloom, the end of Stages I and II of fruit developement, harvest, and 45 days after harvest (leaf fall). At the beginning of Stage II, four additional trees per remaining sampling date were hand-thinned to 15 cm between fruit. Initially, the mean dry weight of trees was 27.1 kg. Unthinned and thinned trees increased 43% and 39%, respectively, in dry weight by 45 days after harvest. Dormant hand-pruning removed about 4 kg of growth. This amount represented nearly the entire season's dry weight of shoot, 1-year-old, and 2-year-old wood growth. The proportion of total tree weight in fruit was increased at harvest in unthinned trees, whereas leaf and 2-year wood dry weight was reduced. A modified harvest index, the proportion of total annual increase distributed to fruit, was 0.50 for unthinned trees and 0.37 for thinned trees. The ratio of annual dry weight increase per unit leaf area was 0.33 and 0.27 kg·m−2 leaf area for unthinned and thinned trees, respectively. The maximum mean leaf area was estimated to be 62.9 × 103 m2·ha−1. The greatest leaf area density, measured at the end of Stage II, was 7.7. Absolute growth rates of vegetative components were highest during Stage II of peach fruit growth, and intermediate during Stage I.
Sweet Corn Seedling Responses to Band-applied Nitrogen, Phosphorus, and Potassium Fertilizers
Authors: Peck Nathan H. , MacDonald George E. , Barnard John
Published: August 2022

The objective of this study was to determine the effects of sources and rates of N, P, and K fertilizers applied in a band at planting and at several planting dates on the rates of growth and concentrations of elements in sweet corn (Zea mays L. var rugosa) seedlings. Sweet corn seedlings were grown under field conditions at 10 planting dates in a fine silt loam soil. Ten sources and blends of N, P, and K fertilizers were applied at planting time at linear increasing rates of 0 to 20 g of element per meter of row in a band placed 5 cm below the seed depth and 5 cm to the side of the seed row. Seedlings grown with blends of N + P + K fertilizers at 5 to 9 g of N, P, and K elements per meter of row had the greatest rates of growth in dry weight per day. The optimum reference concentrations of elements in the sweet corn seedlings with the greatest rates of growth were: 5 mg nitrate-N, 45 mg total N, 4.2 mg P, 45 mg K, 7 mg Ca, 3 mg Mg, 30 μg Zn, 70 μg Mn, 300 μg Fe, and 8 μg Cu per gram of dry weight of the seedlings.
Increasing Yield of Tomatoes with Plastic Mulch and Apex Removal
Authors: Wien H.C. , Minotti P.L.
Published: August 2022

Field and greenhouse experiments were conducted to encourage growth of basal branches of tomato (Lycopersicon esculentum Mill.) through apex removal and use of plastic mulch. In the greenhouse experiment, apex removal (topping) delayed anthesis of the first flowers by 6 days, but then the faster branch growth increased flower cluster numbers more rapidly on topped plants than on untopped plants. In the first field experiment, apex removal and clear plastic mulch stimulated basal branching and led to a 25% increase in yields of the first four harvests, with the combination of treatments having additive effects. Mulching increased leaf concentrations of P, K, Ca, and NO3-N and decreased Na concentrations, whereas topping increased Ca, Mg, and Na concentrations in leaves sampled 24 days after transplanting. In 1985, mulching resulted in a 54% increase in early yields, but topping depressed marketable early yields by 20% because of fasciation (“catfacing”). In 1985, early yield of an early processing line was stimulated more by mulch than were two later-flowering fresh-market cultivars.
Kernel Maturity, Seed Size, and Seed Hydration Effects on the Seed Quality of a Sweet Corn Inbred
Authors: Bennett Mark A. , Waters Luther , Curme John H.
Published: August 2022

To understand early development of seed quality, seed lots of sweet corn (Zea mays L.) inbred PGG-27B were harvested from an increase field at 10 stages of maturity, beginning when kernel moisture was at 59% and continuing to 19% kernel moisture content (42 to 103 days after pollination, respectively). Seed lots were dried, hand-shelled, sized, and tested for standard germination and subjected to the seedling growth cold test (SGCT). Endosperm, embryo, and kernel dry weights, and endosperm : embryo (END:EMB) ratios were monitored as the seed matured. Field tests were planted to determine the influence of kernel maturity, grade, and hydration on stand establishment and early seedling growth. Seeds were partially hydrated by mixing with moist vermiculite and screening from the substrate when seeds had reached 30% moisture content. Results from hydrated seeds were compared to those from seeds at ≈10% seed moisture to determine the effect of presowing seed hydration on seedling establishment. The seed hydration effect depended on the environment, but seed size was shown consistently to influence emergence and early seedling dry weight. Seed harvested at 45% to 54% moisture had better stand establishment than seed harvested at the more typical moisture of near 35%. The stage of maturity, determined by kernel moisture, at which PGG-27B was harvested had little effect on standard germination. Hydrating the seed prior to the SGCT improved seedling growth for all early kernel maturities and all seed grades. Embryo dry weight of composite samples increased steadily up to the fifth harvest period (38% seed moisture), then leveled off. Kernel and endosperm dry weights were more variable at the fifth harvest than at others, but followed the same general pattern. The ratio of END:EMB dry weight decreased from the first to the fifth harvest, where it continued at a value near 4.9 through harvest 10. Seed moisture at harvest, seed size, and presowing seed hydration were shown to influence the seed quality of PGG-27B.
Soluble Sugar Accumulation and Activity of Related Enzymes During Muskmelon Fruit Development
Authors: McCollum T.G. , Huber D.J. , Cantliffe D.J.
Published: August 2022

Changes in soluble sugar composition of muskmelon (Cucumis melo L. var. reticulatus Naud.) mesocarp were followed throughout fruit development. Glucose and fructose, in nearly equal amounts, were the predominant sugars detected during the first 24 days after anthesis. Sucrose began to accumulate 24 days after anthesis and was the predominant sugar present in the ripe fruit. A soluble acid invertase (pH optimum 4.0 to 5.0) was detected in mesocarp extracts. Activity of acid invertase was highest in the young fruit and declined with development. Sucrose synthase activity was also detected in mesocarp extracts. Sucrose synthase activity increased between 18 and 24 days after anthesis and thereafter remained constant. Acid invertase and sucrose synthase appeared to be involved in the metabolism of sucrose during muskmelon fruit development.
Antioxidant Activity in ‘Cortland’ Apple Peel and Susceptibility to Superficial Scald after Storage
Authors: Meir Shimon , Bramlage W.J.
Published: August 2022

‘Cortland’ apples (Malus domestica Borkh.) from both exterior and interior of large trees were harvested over a 25-day period, and samples were stored for 0 to 5.5 months in air at 0°C. Antioxidant activity of peel at harvest was assayed. Hexane extracts of whole fruit were used to estimate α-farnesene and conjugated trienes after 1 to 4 months of storage; these values were correlated with scald development after 3 to 5.5 months of storage, α-Famesene increased during the first 2 months of storage and then decreased, while conjugated trienes increased progressively with storage time. α-Famesene was not affected by harvest date, but conjugated trienes were decreased by later harvest. Conjugated trienes were positively correlated more strongly with scald than was α-farnesene. Antioxidant activity increased with later harvest in both exterior and interior fruit, even though exterior fruit ripened during this time, while interior fruit did not. Antioxidant activity at harvest was negatively correlated more strongly with scald development than was either α-farnesene or conjugated trienes, with r values as high as −0.83. A large optical density (OD) peak at ≈200 nm was detected in the hexane extracts of apples, and it was correlated with antioxidant activity (r = +0.63). OD200 values for harvest extracts were as strongly correlated with scald development after storage as were antioxidant assays. A large number of compounds absorbed at 200 nm, including many with antioxidant activity. We propose that OD200 of hexane extracts is an estimate of antioxidant activity at harvest and may represent a convenient and effective chemical index of scald susceptibility of apples after harvest.
Carbon Dioxide Exchange of ‘Tifgreen’ Bermudagrass Exposed to Chilling Temperatures as Influenced by Iron and BA
Authors: White Richard H. , Schmidt R.E.
Published: August 2022

‘Tifgreen’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] was exposed to 10°/7°C (day/night) temperatures following pretreatment with 120 mg Fe/m2 or 12.4 mg BA/m2 to determine their effects on net photosynthesis (Pn), respiration (Rs), leaf total nonstructural carbohydrate (TNC) content, and turf color at chilling temperatures. Average Pn and Rs rates were reduced 73% and 66%, respectively, by a 72-hr chilling period. Within 2 hr at 30° following chilling, Rs rates returned to prechill rates. However, Pn rates returned to within only 50% of prechill rates during the same recovery period. The lack of full photosynthetic recovery was associated with a 288% increase in leaf TNC. Iron increased Pn rates prior to chilling. This iron effect was associated with increased photosynthetic activity per unit of chlorophyll and was evident before, during, and after the chilling period. BA increased Pn rates before chilling and within 2 hr at 30° following chilling. However, during chilling, Pn rates for the BA treatment were similar to the control. Neither Fe nor BA significantly affected leaf TNC or Rs rates. Iron and BA caused higher turf color scores during chilling. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA).
Germination of Guar Seed under Salt and Temperature Stress
Authors: Vinizky Itamar , Ray Dennis T.
Published: August 2022

The influence of four temperatures (25°, 30°, 34°, and 37°C), five osmotic potentials (0, −0.3, −0.7, −1.1, and −1.5 MPa) and three salts (NaCl, KCl, and Na2SO4) on the germination of three guar [Cyamopsis tetragonoloba (L.) Taub] cultivars (Kinman, Lewis, and Santa Cruz) was tested under laboratory conditions. The results show that germination decreased with increasing salt concentrations. A temperature-salinity interaction was observed with the greatest suppression of germination at the high temperatures (34° and 37°) and salt concentrations (−1.1 and −1.5 MPa). The response varied according to the type of salt, with the lowest germination rate for all three cultivars in Na2SO4 at −0.7 to −1.5 MPa osmotic potentials. The three cultivars showed significant differences in their germination response to salt stress; ‘Kinman’ performed better than either of the two other cultivars in low salt concentrations (0 to −0.7 MPa), but, at high concentrations (−1.1 and −1.5 MPa), the differences were not significant.
Quantitative Genetic Variation for Resistance to Leaf Spot (Ramularia tulasnei) in California Strawberries
Authors: Shaw Douglas V. , Bringhurst Royce S. , Voth Victor
Published: August 2022

Strawberry (Fragaria × ananassa Duch.) seedlings from biparental crosses were planted in two trials at Watsonville, Calif. Sept. 1985 and 1986. The 1985 trial was scored on three dates and the 1986 trial on four dates for leaf spot (Ramularia tulasnei) infection. Individual seedlings were assigned a value of 0 to 5 on each date, with 0 indicating no infection and 5 indicating very severe infection. Average infection scores were lowest for the earliest scoring dates in both years (0.93 and 0.38) and maximum at late scoring dates (2.83 and 1.49). Narrow-sense heritabilities for infection scores estimated using partial diallel analyses were 0.07 and 0.03 for the earliest scoring dates in the two trials and were 0.24 and 0.28 for the latest dates. Early season estimates of broad-sense heritabilities were calculated as 0.13 and 0.03, whereas estimates based on later scorings ranged from 0.32 to 0.52. The low heritabilities for early scoring dates result from incomplete and uneven infection, indicating that selection under field conditions will be most effective under conditions of very high infection. The moderate heritabilities and predicted gains estimated for high-infection conditions suggest considerable opportunity for improvement of leaf spot resistance by recurrent breeding and selection using available quantitative genetic variation.
Addition of Genes for Dwarf Seed (ds) and Spindly Branch (sb) to the Linkage Map of Common Bean
Authors: Awuma Kafui , Bassett Mark J.
Published: August 2022

Linkage detection and estimation procedures based on deviation from expected F2 segregation ratios in common bean (Phaseolus vulgaris L.) were used to localize two genes. The product ratio method of estimation was used with four-class segregations, and the maximum likelihood method was used with three-class segregations and for combining multiple sets of data. A tight linkage of 1.6 ± 1.5 map units (m.u.) was found between dwarf seed (ds) and dark green savoy leaf (dgs), two genes in linkage group VII. A third gene in linkage group VII, stipelless lanceolate leaf (sl), was found to be 18.7 ± 1.6 m.u. from ds. The distance between dgs and sl was found to be 21.2 ± 1.0 m.u., thus establishing that ds is located between dgs and sl. This location of ds supports the contention that ds and tenuis (te), a gene described by Lamprecht, are the same gene. In linkage group IX, an estimate of 4.6 ± 1.5 m.u. was obtained for the linkage between diamond leaf (dia) and progressive chlorosis (prc). Spindly branch (sb) was found to be 15.4 ± 0.7 m.u. from prc and 11.4 ± 1.1 m.u. from dia. Thus, dia is located between sb and prc. The independence of linkage groups VII and IX is demonstrated by the independence of representatives of the two groups.
Scanning Electron Microscope Analysis of Drupelet Morphology of Red Raspberry and Related Rubus Genotypes
Authors: Robbins Jo Ann , Sjulin Thomas M. , Rasmussen H. Paul
Published: August 2022

Scanning electron microscopy was used to measure epidermal hairs and drupelet morphology of raspberry fruit. Significant differences were found among cultivars and selections in drupelet size, total contact area between drupelets, and contact area with hairs between drupelets, hair density index, and hair length. Drupelet numbers also differed. Fruit strength, as measured by cohesiveness, was related to contact area between drupelets, whether hair-covered or not, in conjunction with total drupelet number. Hair density contributed to cohesion in some years with certain cultivars. Resistance to compression was most consistently correlated with total drupelet area and contact area between drupelets alone and in conjunction with hair density.
Apple Fruit Nonstructural Carbohydrates and Abscission as Influenced by Shade and Terbacil
Authors: Polomski Robert F. , Barden John A. , Byers Ross E. , Wolf Dale D.
Published: August 2022

Terbacil, a photosynthetic inhibitor, and shade applied to apple (Malus domestica Borkh) limbs and whole trees altered the contents of fruit nonstructural carbohydrates and induced fruit abscission. Shade (92%) from 5 to 15, 10 to 20, 15 to 25, 20 to 30, and 25 to 35 days after full bloom (DAFB) induced fruit abscission. At 15 and 20 DAFB, fruit from limbs shaded for 10 days contained less total nonstructural carbohydrates (TNC) than fruit from limbs shaded for 0 or 5 days. Terbacil at 50 and 100 ppm applied to whole ‘Redchief Delicious’ trees at 15 DAFB markedly inhibited net photosynthesis. Fruit dry weight, TNC, total sugars, and reducing sugars declined with increasing rates of terbacil and 100 ppm resulted in abscission of all fruit. Trees treated with 0 and 50 ppm retained 4.6 and 1.4 fruit per cm2 of limb cross sectional area (LCSA), respectively. Terbacil at 75 ppm and 92% shade were applied to whole ‘Redchief Delicious’ trees at 18, 23, and 28 DAFB. Fruit dry weight and contents of total sugars and reducing sugars were lowered by shading and terbacil. Shade for 5 or 10 days induced total fruit drop. Terbacil at 75 ppm resulted in 0.8 vs. 2.9 fruit per cm2 of LCSA on the controls. Chemical name used: 5-chloro-3-(1,1-dimethylethyl)-6-methyl-2,4(1H,3H)-pyrimidinedion (terbacil).
Time of Day at Harvest Influences Carbohydrate Concentration in Crisphead Lettuce and Its Sensitivity to High CO2 Levels after Harvest
Authors: Forney Charles F. , Austin Rodney K.
Published: August 2022

Concentrations of starch and sugars were measured in the cap leaf (leaf no. 1) and in every fifth leaf (5, 10, 15, 20) in heads of crisphead lettuce (Lactuca sativa L.) harvested at 0700 hr (AM) or 1400 hr (PM) PDT. Starch content increased in the cap leaf from the AM to the PM harvest, but remained unchanged in other leaves. Sucrose concentration was <5 mg·g−1 dry weight in AM-harvested lettuce, but the cap leaf, leaf 20, and stem tissue contained 43, 24, and 61 mg·g−1 dry weight, respectively, in lettuce from the PM harvest. AM harvested lettuce contained 70% to 260% more glucose and 20% to 120% more fructose than PM-harvested lettuce. Glucose and fructose concentrations were greatest in leaf 10 (110 and 120 mg·g−1 dry weight, respectively) and decreased 20% to 50% in inner and outer leaves. Exposure of lettuce to 7.5% or 10% CO2 for 12 days at 2.5°C followed by air for 3 days at 10° caused more severe injury on AM- than on PM-harvested lettuce. Injury occurred primarily on leaves 7 through 17, with those between leaves 10 and 15 being most severely affected. High reducing sugar content at harvest did not appear to decrease the sensitivity of lettuce to high CO2 during storage.
Enhancement of the Release of Protoplasts and Pectin from Tomato Locular Gel by Pectin Methylesterase
Authors: Burns Jacqueline K. , Pressey Russell
Published: August 2022

Pectin methylesterase (PME, EC 3.1.1.11) was added to locular gel and pericarp of ripening tomato (Lycopersicon esculentum Mill.) and cell wall alterations were examined. Treatment of mature tomato locular gel with purified PME resulted in release of protoplasts. No protoplasts could be detected from immature locular gel or pericarp at any ripening stage examined under similar conditions. Net solubilization of pectins occurred with PME treatment in both tissues. Pectins solubilized with buffer or PME were of high molecular weight. Maximum protoplast release and pectin solubilization occurred at pH 5.0. Increased pectin solubilization in locular gel and pericarp is a result of polygalacturonase action on PME-induced deesterified pectin, the preferred substrate. Release of protoplasts from PME-treated mature locular gel suggests that maturation in this tissue involves alterations in cell wall structure that do not occur in pericarp.
Source-sink Relationships in Sweet Potato
Authors: Bouwkamp J.C. , Hassam M.N.M.
Published: August 2022

Relationships between storage root dry weight and vine dry weight, storage root number, and harvest index were determined from yield, date of harvest, and spacing trials. The relative importances of source, sink, and partitioning rate effects change during the growing season and differ among cultivars and groups of cultivars. Under Maryland conditions, vine effects predominate over storage root number effects, both in terms of effects on root yield and effects on apparent partitioning rates. Cultivars and groups of cultivars showing strong root sink effects are generally low-yielding.
Growth Responses of Young Peach Trees and Changes in Soil Characteristics with Sod and Conventional Planting Systems
Authors: Welker William V. , Glenn D. Michael
Published: August 2022

Peach [Prunus persica (L.) Batsch] trees were planted in four soil management systems (cultivated, herbicide, mowed sod, and killed sod) in 1982 and grown through 1984. A companion study was established in 1984 with three systems (cultivated, herbicide, and killed sod). Tree growth and fruit yield were greatest when trees were planted and managed in a killed sod system. Establishing a living sod before planting the trees, and then killing the sod with herbicides, prevented the depletion of soil organic matter and increased water infiltration rates, aggregate stability, macroporosity, and microbial respiration rates compared to conventional systems. The changes in soil structure persisted for 2 to 3 years.
Postharvest Density Changes in Membranes from Ripening Avocado Fruits
Authors: Dallman Thomas F. , Eaks Irving L. , Thomson William W. , Nothnagel Eugene A.
Published: August 2022

An investigation was performed with the goal of identifying, at the biochemical level, organelles that undergo postharvest change during ripening in avocado fruits (Persea americana Mill. cv. Hass). Membrane vesicles from mesocarp tissue at defined stages of ripening were fractionated by linear density gradient centrifugation and then assayed for characteristic marker activities. These measurements indicated that the Golgi and plasma membranes increased in buoyant density from 1.11 g·cm−3 to 1.14 g·cm−3 and from 1.15 g·cm−3 to 1.17 g·cm−3, respectively, during ripening. The endoplasmic reticulum exhibited a smaller increase in density, while thylakoids and mitochondrial membranes showed no shifts in density during ripening. These membrane changes were apparent at the peak (predicted from measurements of C2H4 production) of the respiratory curve that characterizes climacteric fruit ripening and were sustained for at least 6 days past the respiratory peak. Colorimetric lipid analyses of plasma membrane-enriched fractions indicated that the buoyant density increase during ripening was due, in part, to a decrease in the glycolipid : protein ratio. Electrophoretic analyses of fractions containing peak total activities of Golgi, thylakoids, or plasma membrane revealed several changes in the polypeptide banding patterns during ripening.
Variability for Critical Photoperiod for Tuberization and Tuber Yield Among Monoploid, Anther-derived Genotypes of Solanum phureja
Authors: Owen H.R. , Veilleux R.E. , Haynes F.L. , Haynes K.G.
Published: August 2022

Monoploid genotypes (2n = x = 12), derived by anther culture of a diplandrous (2n pollen-producing) clone of Solanum phureja Juz. & Buk., a South American diploid potato species, were examined for their use in germplasm development. Nine monoploid genotypes and the anther-donor genotype were grown in three chambers (10-, 14-, and 18-hr daylengths) to examine the effect of photoperiod on tuber yield and to determine the variability for critical photoperiod for tuberization. Significant differences were found among the monoploid genotypes for tuber weight and tuber number. Longer photoperiod treatments decreased and delayed tuberization. Axillary tuber formation from single-node cuttings was used to estimate the onset of tuber induction and demonstrated variability among monoploid genotypes for critical photoperiod for tuberization.
Inter- and Intraspecific Variation in California Black Walnuts
Authors: McGranahan Gale H. , Hansen John , Shaw Douglas V.
Published: August 2022

Genetic variation in vigor, phenology, and branching in juvenile seedlings of Juglans californica and J. hindsii was investigated. Significant differences between species were detected in traits that reflect vigor (height, diameter, volume), in phenological traits (dates of leafing out and leaf drop), and in branching. J. californica was generally more vigorous, more branched, leafed out earlier, and dropped leaves later than J. hindsii. When species were analyzed separately, seed source was a highly significant source of variation for phenological traits and branching in J. hindsii. Upper estimates of heritability for phenological traits ranged from 0.47 to 0.88. The results of this study suggest that J. hindsii may have had a history of differentiation and adaptation to latitude, elevation, or other climatic characters. Conservation of germplasm resources in J. hindsii will be essential to maintain the purity of the species and to provide resources for studying the species and breeding rootstock for J. regia, the Persian walnut.
Genotypic Variation and Genotypic Correlations for Sugars and Organic Acids of Strawberries
Authors: Shaw Douglas V.
Published: August 2022

Genotypic variances and genotypic correlations were estimated for soluble solids content (SSC), titratable acids, and their major constituents, using strawberry genotypes (Fragaria × ananassa) not previously selected for flavor or other commercial traits. Genotypic variances estimated for SSC and total sugars were nonsignificant, whereas those estimated for acids were significant and large. Relative expression of acids was stable throughout the season; large genetic × harvest date interactions reduced genotypic consistency for SSC. Despite the absence of detectable genotypic variation for SSC and total sugars, significant genotypic variation was detected for sucrose, glucose, and fructose, and the relative expression of these sugars was stable over harvest dates. The total allocation of sugar to fruit appears fixed, but the distribution pattern among sugar constituents at commercial ripeness is variable. This interpretation was supported by the observation of a strong negative genotypic correlation between sucrose and its components, glucose and fructose. These results suggest that opportunity exists for genetic improvement of acids, but that selection response for SSC will be difficult to obtain.
Chilling Requirement and Post-rest Heat Accumulation as Related to Difference in Time of Bloom Between Peach and Western Sand Cherry
Authors: Werner Dennis J. , Mowrey Bruce D. , Young Eric
Published: August 2022

The basis for the difference in time of bloom between ‘Redhaven’ peach [Prunus persica (L.) Batsch] and western sand cherry (Prunus besseyi Bailey) clone ‘Cornell-Geneva (CG) 3-24’ was investigated. Based on 3 years of field observation, average bloom date (50% of buds) of ‘Redhaven’ was 9 days earlier than ‘CG 3-24’. Greenhouse forcing of field-collected shoots and artificially chilled trees suggested that the flower bud chilling requirement of these two clones is similar. Forcing of artificially chilled trees under different post-rest temperature regimes revealed that the base temperature for flower bud heat accumulation was lower in ‘Redhaven’ than in ‘CG 3-24’ (4.3° vs 7.0°C, respectively). Values of Q10 for flower bud development were 2.2 and 2.8 for ‘Redhaven’ and ‘CG 3-24’, respectively. These results suggest that the basis for difference in time of bloom is due to a difference in the base temperature for heat accumulation and is not related to chilling requirement.
Evaluation of Nutrient Deficiency and Micronutrient Toxicity Symptoms in Florists’ Hydrangea
Authors: Bailey Douglas A. , Hammer P. Allen
Published: August 2022

In the article “Evaluation of Nutrient Deficiency and Micronutrient Toxicity Symptoms in Florists’ Hydrangea”, by Douglas A. Bailey and P. Allen Hammer (J. Amer. Soc. Hort. Sci. 113(3):363–367, May 1988), the following corrections should be noted: 1) In Table 3, percent dry weight of N for the –N treatment should read “1.40”, not “4.40”; 2) the significance levels in footnote z of Table 3 should read “0.05 ≥ α ≥ 0.01 (*), at 0.01 ≥ α > 0.001 (**), or at α ≤ 0.001 (***)”; 3) Tables 4 and 5 are numbered incorrectly—they should be switched; and 4) the significance levels in footnote z of the renumbered Table 5 should read “0.01 ≥ α > 0.001 (**) or at α ≤ 0.001 (***)”.
Germination of Bahiagrass in Response to Temperature and Scarification
Authors: Marousky Francis J. , West Shirlie H.
Published: August 2022

The influence of temperature and various scarification treatments on the physical changes of the lemma and germination of bahiagrass (Paspalum notatum Flugge) were studied. Mechanically scarified seeds readily germinated on an agar medium. Acid-scarified seeds germinated better than untreated seeds, but not as readily as mechanically scarified seeds. All caryopses excised from nongerminated acid-scarified seeds readily germinated on an agar medium after 17 days. Excised caryopses were placed on a temperature gradient bar corresponding to positions at 15.5°, 21°, 26.5°, 32°, and 37.5°C. All caryopses germinated at 21° to 37.5°, but germination and seedling growth were best at 32° to 37.5°. Lipase and acid scarification improved germination when seeds were held at 24°, but did not enhance germination when seeds were held at 32°. Scanning electron microscopy revealed that acid scarification removed the cuticular substances of the lemma and the substances in the fissure of the germinating lid, probably facilitating entrance of the water and earlier emergence of the coleorhiza. The data suggest that the lemma and palea are physical barriers in bahiagrass.
Abscisic Acid and ACC Content of Chinese Cabbage during Low-oxygen Storage
Authors: Wang Chien Yi , Ji Zuo Liang
Published: August 2022

The abscisic acid (ABA) concentration in Chinese cabbage increased during storage at O°C in air. This increase was reduced in a low-O2 (1%) atmosphere. The suppressing effect of low O2 on ABA levels was detected in outer laminae, outer midribs, inner laminae, and inner midribs, but was particularly conspicuous in outer laminae. At the end of 12 weeks of storage, ABA content in outer laminae from 1% O2 storage was less than half of that from air storage. Low-oxygen storage also delayed the yellowing of outer laminae and maintained a higher chlorophyll content. The levels of ACC in all parts of Chinese cabbage were low and increased only in outer midribs after 2 months of storage, corresponding to the appearance of tissue browning in the outer midribs. Low-O2 storage delayed both the rise in ACC and the occurrence of tissue browning. Chemical name used 1-aminocyclopropane-1-carboxylic acid (ACC).
Transpiration and Water Use of Potted Floricultural Plants Under Low-light Conditions
Authors: Rajapakse Nihal C. , Kelly John W. , Reed David Wm.
Published: August 2022

Potted foliage and floricultural species were evaluated for transpiration rates under low-light conditions. Environmental conditions during the experiment were 25° ± 2°C, 75% ± 10% RH, and 20 μmol·s−1 ·m−2 (400−700 nm) light intensity. Leaf cuticular and stomatal morphology were characterized with scanning electron micrographs. Coleus had the highest transpiration rate, Chrysanthemum was intermediate, and Ficus, Peperomia, and Epipremnum had the lowest transpiration rates. Abscisic acid (ABA) treatment reduced the daytime transpiration, which eliminated the diurnal fluctuation of transpiration in all species but had no effect on night transpiration, except in Coleus. Assuming complete stomatal closure at night with ABA treatment, cuticular transpiration accounts for 43% to 80% of the total transpiration rate under low-light conditions. This result points to the importance of leaf cuticular and stomatal characteristics in controlling water use of plants under low light or dark-storage. Species differed in cuticular characteristics, stomatal frequency and size, and leaf area. Stomatal frequency correlated well with transpiration rates, except in those species with unique stomatal morphologies, such as Ficus, with sunken stomates surrounded by a protruding ridge. Coleus and Chrysanthemum developed less epicuticular wax than the other species. Epicuticular and stomatal characteristics were correlated with transpiration rates of these species.
Multivariate Analysis of a Sour Cherry Germplasm Collection
Authors: Hillig Karl W. , Iezzoni Amy F.
Published: August 2022

Morphological traits of 16 sour cherry (Prunus cerasus L.) cultivars and of hybrid and open-pollinated seedlings of germplasm collected in eastern Europe were evaluated with principal component (PC) analysis. Due to the character loadings of the first three PCs in each analysis, some of the PCs can be interpreted as representing gradations between morphologies characteristic of the two presumed progenitor species, sweet cherry (P. avium L.) and ground cherry (P. fruticosa Pall.). Genetically related cultivars and families tend to cluster, indicating that there is a significant genetic component to the underlying patterns of morphological variation. Families of cold-hardy Russian cultivars generally show a greater morphological resemblance to ground cherry than do families of less cold-hardy cultivars, suggesting that selective forces may also have contributed to the patterns of morphological variation detected.
Proliferative Somatic Embryogenesis from Zygotic Embryos of Grapevine
Authors: Stamp James A. , Meredith Carole P.
Published: August 2022

Zygotic embryos isolated from mature berries of Vitis longii Prince and V. vinifera L. cvs. Chardonnay, French Colombard, Grenache, and White Riesling produced somatic embryos when cultured on solid Nitsch and Nitsch medium. Explants of V. vinifera cv. Pinot noir did not produce somatic embryos. The highest incidence of somatic embryogenesis occurred on medium containing (all in mg·liter−1) 1.0 NOA plus 0.2 BAP, except in ‘White Riesling’, where 1.0 NOA plus 1.0 BAP was optimal. Somatic embryos developed asynchronously from a mass of white proembryos and passed through globular, heart, and torpedo-shaped stages. Embryos proliferated by budding at the surface of globular embryos. With regular transfers, embryogenic tissues remained morphogenically competent for up to 1 year. Zygotic embryo explants cultured on medium without growth regulators usually germinated within 10 days and produced healthy seedlings. About 40% of somatic embryos germinated after isolation from their parental cultures and transfer to fresh medium. At the concentrations tested, NAA, BAP, and GA3 did not improve germination frequency over that obtained with basal medium and, in some cases, severely reduced germination. Plants were established in the greenhouse and no morphological abnormalities were observed. Chemical names used: 6-benzylam-inopurine (BAP); gibberellic acid (GA3); 2-(l-naphthyl)acetic acid (NAA); 2-naphthoxyacetic acid (NOA).
Maturity, Storage Quality, Carbohydrate, and Mineral Content of ‘Goldspur’ Apples as Influenced by Rootstock
Authors: Drake Stephen R. , Larsen Fenton E. , Fellman John K. , Higgins Stewart S.
Published: August 2022

Influences of rootstocks on ‘Goldspur Golden Delicious’ apple (Malus domestica Borkh.) respiration rate, ethylene evolution, skin color, firmness, internal color, soluble solids content (SSC), acidity, carbohydrate, and mineral content were evaluated over an extended harvest and after cold storage. At first harvest, fruit from trees on seedling rootstock entered the climacteric (as determined by ethylene evolution) first (after 10 days) followed by fruit from M.26 trees, while apples from trees on MM.111 required 16 days. After 60 days in storage, CO2 and ethylene production were greatest for apples from trees on MM.111 rootstock. Fruit from trees on M.26 developed more external color, contained more acids, had a higher SSC, and appeared to mature between apples grown on the other two rootstocks. Fruit from trees on M.26 were firmer than those on MM.111. Apples from trees on seedling rootstock contained less fructose, glucose, and sucrose than apples from M.26 or MM.111. Calcium content was highest in fruit from trees on M.26.
Natural Branching in Citrus Juice Vesicles
Authors: Tisserat Brent , Jones Danny , Galletta Paul D.
Published: August 2022

Juice vesicles in several Citrus species and cultivars differentiate additional vesicle apex primordia. Four distinct types of juice vesicles were described and quantified in citrus fruits: solitary (single stalk/single vesicle body/single apex primordium), dual-tipped (single stalk/single vesicle body/dual apex primordia), multiple-tipped (single stalk/single vesicle body/multiple apex primordia) and branched (single-stalk/multiple vesicle bodies/multiple apex primordia). The type and frequency of branching varies considerably among species and within cultivars. Branching was found in grapefruit, mandarin, pummelo, and tangelo, but not in blood orange, citron, lemon, lime, navel orange, rough lemon, sour orange, sweet orange, Valencia orange, and several other species. ‘Kao Panne’ pummelo [Citrus maxima (J. Burman) Merrill] exhibited one of the highest rates of vesicle branching, with 72% of its vesicles exhibiting this condition. The average number of branching vesicles produced per stalk was 3.7 for this cultivar. The frequency of branching was below 50% in other branched groups (e.g., grapefruit, mandarin, and tangelo).
Pollen Parent Effect on Outcrossing Rate in ‘Hass’ and ‘Fuerte’ Avocado Plots during Fruit Development
Authors: Degani Chemda , Goldring Anat , Gazit Shmuel
Published: August 2022

Outcrossing rates in ‘Hass’ and Fuerte’ avocado (Persea americana Mill.) blocks were determined during fruit development using the isozyme systems of malate dehydrogenase (MDH, EC 1.1.1.37), leucine aminopeptidase (LAP, EC 3.4.11.1), and triosephosphate isomerase (TPI, EC 5.3.1.1) as genetic markers. Abscission of avocado fruitlets was selective and was greatly influenced by the pollen parent. Thus, in ‘Hass’ trees subjected to crosspollination by ‘Ettinger’ and ‘Fuerte’, the population of ‘Hass’ fruitlets 1 month after fruit set consisted mainly of ‘Hass’ selfs; however, during fruit development, the rate of ‘Hass’ selfs decreased and the rate of ‘Hass’ hybrid fruitlets produced by ‘Ettinger’ and ‘Fuerte’ increased. By the end of fruit abscission, the surviving mature ‘Hass’ fruits were mostly ‘Ettinger’ hybrids. The ‘Hass’ fruit yield was found to correlate significantly with the rate of outcrossing with ‘Ettinger’. When ‘Ettinger’ served as a pollen parent for ‘Fuerte’, the outcrossing rate in trees adjacent to ‘Ettinger’ was about 40%, which shows that cross-pollination among avocado cultivars of the same flowering group can be substantial at close proximity. The outcrossing rate in ‘Fuerte’ diminished with increasing distance from ‘Ettinger’, but no effect on yield was observed.
Inhibitory Activity of Asparagus Root Tissue and Extracts on Asparagus Seedlings
Authors: Hartung A.C. , Putnam Alan R. , Stephens C.T.
Published: August 2022

Asparagus (Asparagus officinalis L.) root tissue and root extracts were used to investigate the previously reported release of toxic chemicals from senescing root tissue. Greenhouse studies showed that the severity of crown or root rot of asparagus seedlings increased in direct proportion to increased amounts of dried root tissue incorporated into soil with either F. oxysporum f. sp. asparagi, F. moniliforme, or a combination of these two pathogens. When excised asparagus roots were treated with increasing concentrations of a water extract of dried asparagus root tissues, electrolyte efflux increased, peroxidase activity decreased linearly, and respiration decreased. Active components in the extracts were heat-stable. Our data suggest allelochemicals of asparagus may have direct physiological and biochemical effects on asparagus plants that predisposes them to fusarium diseases.
Identification of Almond Cultivars by Pollen Isoenzymes
Authors: Cerezo M. , Socias i Company R. , Arús P.
Published: August 2022

Horizontal starch gel electrophoresis was applied to the study of almond identification [Prunus amygdalus Batsch, syn. P. dulcis (Mill.) D.A. Webb] using pollen from 44 cultivars of different origin. Variability was found in all of the nine enzymatic systems analyzed (PGM, AAT, GPI, LAP, 6PGD, AcP, CAT, IDH, and ADH). The enzymatic systems with the highest discriminating possibilities were PGM, CAT, AcP, and LAP. This variability enabled the 44 cultivars to be distinguished with the exception of two pairs.
Procedures for Field and Greenhouse Screening of Prunus Genotypes for Resistance and Tolerance to Root Lesion Nematode
Authors: Culver Dennis J. , Ramming David W. , McKenry Michael V.
Published: August 2022

Procedures were developed for screening Prunus spp. and related genotypes for resistance/tolerance to the root lesion nematode Pratylenchus vulnus Allen and Jansen in the field and greenhouse. Inoculum rates tested were 150 and 1500 nematodes per 375-cm3 pot in the greenhouse and 300 and 3000 nematodes per planting site in the field. Nematodes per gram of root was a reliable indication of the relative resistance of a genotype to initial invasion and establishment of P. vulnus at 122 days after treatment (DAT). At 122 DAT, more distinct differences between genotypes were seen at the low inoculum rate than at the high rate. The most sensitive growth measurement in the field appeared to be the relative diameter increase at 175 DAT. Significant reductions in Ca++ and Mg++ in new rootlets were also a reliable indication of nematode effects on a genotype in both the field and the greenhouse. Using these criteria, Pistacia atlantica Desf. was classified as resistant, ‘Nemaguard’ peach [Prunus persica (L.) Batsch] as susceptible, and P. besseyi Bailey, ‘Royal’ apricot (P. armeniaca L.), and ‘Myrobalan 29C’ plum (P. cerasifera Ehrh) as tolerant in decreasing order of tolerance.
Comparison of Subsurface Trickle and Furrow Irrigation on Plastic-mulched and Bare Soil for Tomato Production
Authors: Bogle Clyde R. , Hartz Timothy K. , Nunez Carlos
Published: August 2022

Subsurface trickle and furrow irrigation of fresh-market tomato (Lycopersicon esculentum Mill.), with or without plastic mulch, were compared for three consecutive growing seasons. Plots were irrigated when available soil water was 40% depleted. Marketable tomato yield was 22% greater for plants grown with trickle irrigation than with furrow irrigation. Use of black plastic mulch resulted in 31% and 16% greater marketable tomato yield in Spring 1983 and 1984, than similar bare-soil (unmulched) treatments, respectively. In Fall 1983, use of white/black (top/bottom) laminated plastic mulch reduced yields by 12% compared to similar unmulched treatments. Total water (irrigation plus precipitation) applied to furrow-irrigated plots nearly equalled pan evaporation (Epan). Trickle-irrigated plots received < 45% of Epan in all seasons, resulting in increased water-use efficiency with drip irrigation. Trickle irrigation as applied did not affect soluble salts concentration in the soils.
Crop Productivity and Morphology of Petunia and Geranium in Response to Low Night Temperature
Authors: Merritt Richard H. , Kohl Harry C.
Published: August 2022

Seedlings of Petunia hybrida ‘Snow Cloud’ and Pelargonium × hortorum ‘Red Elite’ and ‘Cardinal Orbit’ were grown to anthesis at day air temperatures of 27° ± 3°C (9 hr) and either 7° ± 3° or 18° ± 3° night air temperatures (15 hr). Petunia crop productivity (CP, grams of dry matter produced per square meter of crop) and crop productivity efficiency (CPE, percentage of photosynthetic photon flux incident on the crop stored in the form of crop dry matter) were the same at both temperature regimes from canopy closure to anthesis, but anthesis was delayed 10 days at 7°. Petunias grown at 7° had four more basal branches and were only one-third the height of petunias grown at 18° (12 vs. 37 cm). CP and CPE were 20% lower for geraniums grown at 7° compared to CP and CPE for geraniums grown at 18°. The geraniums grown at 7° flowered 3 weeks later, were more compact, and were 16 to 19 cm shorter than geraniums grown at 18°.
Hydrology of Horticultural Substrates: II. Predicting Physical Properties of Media in Containers
Authors: Milks Robert R. , Fonteno William C. , Larson Roy A.
Published: August 2022

Handling and preparing growing media can have pronounced effects on the “intensity variables” bulk density and equilibrium volume wetness through changes in pore size distribution. These changes in turn affect the container “capacity variables”: the absolute amounts of medium, air, and water in a container. A nonlinear moisture retention function was combined with container geometry in an equilibrium capacity variable (ECV) model that provided accurate predictions of total porosity, container capacity, air space, unavailable water, available water, and solid fraction for several container-medium combinations.