bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of CPPU and NAA on Fruit Growth and Cropping of Redchief `Delicious'
Authors: Bukovac Martin J. , Neilsen John C. , Hull Jerome
Published: February 2019

NAA is commonly used for fruit thinning of apples. However, with spur-type `Delicious' fruit, size may be less than expected based on the remaining crop load. Attempts to enhance fruit size on NAA-thinned trees with benzyladenine (BA) resulted in an interaction causing an increase in small (≤64 mm) fruit. CPPU [N-(2-chloro-4-pyridinyl)-N'-phenylurea], a highly active cytokinin in promoting parthenocarpy and growth of a number of fruit, was evaluated alone and with NAA for its effects on cropping and fruit growth in Redchief `Delicious'. High-volume sprays of CPPU were applied at 0, 2.5, 5, and 10 mg·L–1 to 13-year-old trees at 7.26 mm king fruit diameter. NAA was applied at 15 mg·L–1 with and without CPPU at 5 mg·L–1. Each treatment consisted of a single tree replicated four times. Response was evaluated by determining yield per tree and fruit size distribution at harvest. CPPU increased the amount of large (≥70 mm) fruit produced without significantly reducing yield. The amount of large fruit produced was 35, 71, 91 and 85 kg/tree for the nonthinned control (NTC) and CPPU at 2.5, 5, and 10 mg·L–1, respectively. NAA (15 mg·L–1) reduced yield by 39 kg/tree and increased amount of large fruit by 44 kg/tree. When CPPU (5 mg·L–1) was oversprayed with NAA (15 mg·L–1), yield was reduced by 30 kg/tree, and amount of large fruit was increased by 56 kg/tree compared to the NTC. The interaction was not significant for yield but was significant (P = 0.01) for amount of large fruit produced. Seed content was significantly reduced by NAA and CPPU, the effect being greater for NAA and in small (51 to 56 and 57 to 63 mm) than in large (76 to 82 mm) fruit. These data showing no significant inhibition of fruit growth with a combination of NAA and CPPU in Redchief `Delicious' are in contrast with findings for a related cytokinin, BA, where fruit growth was depressed significantly when combined with NAA.
Further Studies on Enhancement of Transcuticular Penetration of NAA with Spray Additives
Authors: Fader Royal G. , Luque Patricia , Bukovac Martin J.
Published: February 2019

The cuticle is the prime barrier to penetration of foliar applied plant growth regulators, which must penetrate and be transported to a reaction site before a response can be induced. Urea has enhanced performance of Fe and Zn foliar sprays and a mixture of urea and ammonium nitrate (WAN) the performance of some herbicides. The mechanism of this enhancement is not clear. We find that urea and UAN increased 14C-NAA transport across enzymatically isolated tomato fruit cuticular membranes (CM) from simulated spray droplets using a finitedose diffusion system. The initial rate and total amount of NAA penetrated was significantly increased relative to NAA alone, the enhancement being greater for UAN than urea (total amount 101% vs. 78% at 120 hours) and for the NAA anion (pH 5.2, pKa 4.2) than for the nondissociated (pH 3.2) moiety. When evaluating the concentration effect of urea and NH4NO3 individually, the greatest enhancement with urea was at 62 mm and with NH4NO3 at 8 mm. Generally the effect of urea was significantly less than NH4NO3 (+24% vs. 296%). NAA penetration was greater with NH4NO3 than with KNO3 or Ca(NO3)2 or when the nitrate anion was replaced with sulfate or phosphate. Transcuticular penetration of NAA was enhanced greatly (190% in 120 hours) on removal of cuticular waxes; however, penetration was further increased (252% in 120 hours) by adding 8 mm NH4NO3. Methylamine hydrochloride (CH3NH2.HC1, 8 mm) also increased NAA diffusion, the initial slopes (>8 hours) were 23, 14, and 2 pmols·h–1 for methylamine, ammonium nitrate, and NAA alone, respectively, while the percent of applied that penetrated after 120 hours was 68.5, 67.6, and 21.4 for methylamine, ammonium nitrate, and NAA alone, respectively. The enhancement of NAA penetration by NH4NO3 equaled or exceeded that obtained with a group of surfactants of diverse chemistries. When the surfactant Triton X-100 was compared with NH4NO3, initial penetration was more rapid with ammonium nitrate (11.7 vs. 7.3 pmols·h–1) but percent penetrating after 120 hours was greater for Triton X-100 (80.5 vs. 66.8). The possible action of NH4NO3 on NAA uptake will be discussed.
Using Ethephon to Stimulate Synchronous Ripening of Saskatoon Fruit
Authors: McGarry Roisin , Ozga Jocelyn A. , Reinecke Dennis M.
Published: February 2019

Ethephon was applied in two consecutive years to saskatoon (Amelanchier alnifolia Nutt.) shrubs (`Northline' and `Smoky') to determine its effects on synchronizing fruit ripening. Ripeness can be visually assessed by color (green = immature; red = mature, not ripe; purple = mature, fully ripe). Ethephon (applied when fruit were ≈ 70% red) at 250, 500, and 1000 ppm increased the percentage of ripe fruit obtained from `Northline' by 2%, 4%, and 6%, respectively. Due to pronounced seasonal yield differences for `Smoky', ethephon had no effect on the percentage of ripe fruit obtained in 1994. However, in 1995, ethephon (applied at 70% red fruit stage) at 500 and 1000 ppm increased the percentage of ripe fruit obtained from `Smoky' by 4% and 2%, respectively. Fruit quality, evaluated with respect to surface color development, flesh firmness, fruit size, soluble solids concentration, titratable acidity, and the soluble solids: titratable acids ratio, was not significantly affected by ethephon treatments. This work was supported in part by AARI-FFF grant no. 940442.
Regulation of Gycolytic Metabolism in Asparagus under Low-oxygen, High-carbon-dioxide Atmospheres
Authors: Silva S.M. , Herner R.C. , Beaudry R.M.
Published: February 2019

Asparagus (Asparagus officinallis L. `Giant Jersey') was stored a in flow-through system at 0°C under levels of O2 ranging from 0.1 to 21 kPa in combination with three levels of CO2 (0, 10 and 20 kPa) for 21 d. The resulting changes in RQ and soluble sugars were monitored. The levels of sucrose were higher at 0 kPa of CO2 and at O2 levels >2 kPa; however, those levels were extremely reduced at combinations of high CO2 and low O2. Glucose levels were higher at 0 kPa CO2 when O2 concentrations levels were >1.5 kPa compared to CO2 at 10 and 20 kPa. Fructose levels were maintained higher with CO2 at 20 kPa for all levels of O2, showing lower levels as CO2 decreased. Glycolytic intermediates were evaluated to support the sugar accumulation data. Phosphorylated intermediate levels were altered in spears by CO2 and O2 treatments. Glycolytic control point enzymes were analyzed and may account for sugar accumulation and/or degradation induced by the atmospheric treatments.
Water Stress-induced Heat Tolerance in Geranium and its Association with Accumulation of Dehyrins and HSC 70 Proteins
Authors: Arora Rajeev , Dharmalingam S.P. , Bearce B.C.
Published: February 2019

Evidence is accumulating in favor of a linkage at the cellular level between various abiotic stresses. We conducted a study to evaluate the effect of water stress on the heat tolerance of zonal geraniums. Water-stress was imposed as previously described. Leaf water potential (LWP, MPa), relative water content (RWC, percent), and heat-stress tolerance (HST; LT50, defined as temperature causing half maximal percent injury based on electrolyte leakage) were measured in control, stressed, and recovered (watering restored as in controls) plants. Proteins were extracted from the leaves following the treatments. SDS-PAGE and immunoblotting were performed using standard procedures. Immunoblots were probed with antibodies to dehydrin (T. Close) and 70-kDa heat shock cognate (HSC 70 of spinach) proteins (C. Guy). Data indicate that 1) LXWP and RWC in control and stressed plants were –0.378 and –0.804 MPa and 92.31% and 78.69%, respectively; 2) stressed plants exhibited a significant increase in HST compared to control (LT50 of 55°C vs. 51°C), which was associated with the accumulation of several heat-stable, dehydrin proteins (26 to 50 kDa), and of cytosolic and ER luminal (BiP) HSC 70 proteins; 3) in recovered plants, LXWP, RWC, and HST reversed back to the levels of control concomitant with the disappearance or reduction of dehydrins and HSC 70 proteins. These results suggest that specific stress proteins may play a role in development of heat stress tolerance.
Heat-shock-induced Chilling Tolerance in Malvaceous Seedlings
Authors: Mangrich M.E. , Saltveit M.E.
Published: February 2019

Crops indigenous to the tropics and subtropics and some temperate crops suffer physiological injury when exposed to temperatures <12°C. Heat shock has induced chilling tolerance in a number of sensitive species (e.g., corn, cucumber, and tomato), but not in okra. To study this anomaly, we investigated the chilling sensitivity and heat shock response of a variety of Malvaceous species (i.e., cotton, hibiscus, kenaf, and okra). Seedlings with 8- to 12-mm long radicles were exposed to heat shock temperatures of 40 to 45°C for 2 to 12 minutes. Heat shocks were applied by two methods, floating the seeds in petri dishes on heated water and immersing the seeds in the heated water. The seedlings were held at 20°C for 2 hours after the heat treatments and then chilled at 2.5°C for 3 days. After chilling, seedlings were placed at 25°C for 3 additional days. The growth at 25°C was used as an assessment of chilling injury. Although there was a great deal of variability among the seedlings, a significant number of the okra and kenaf seedlings were more tolerant to chilling after heat shock: (i.e., more growth subsequent to chilling) compared to nonheat-shocked controls. More chilling tolerance was induced by the floating method than the immersion method. The response of cotton seedlings to heat-shock was variable, and the seedlings appeared damaged by even slight heat treatments (i.e., 4 minutes at 40°C). The variability in the capacity of heat-shocks to induce chilling tolerance in seedlings of Malvaceous species will be discussed.
Utility of Random Amplified Polymorphic DNAs for Determining Intraspecific Relationships in Cucumis
Authors: Staub J. , Box J. , Meglic V. , Horejsi T.F. , McCreight J.D.
Published: February 2019

Principal component analyses of variation at 21 isozyme and 43 random amplified polymorphic DNA (RAPD) loci in eight cucumber (GY-14a, G421, H-19, WI 2757, and PIs 432860, 458845, and 183967) and seven melon [Top Mark (TM), Doublon, Green Flesh Honeydew (GFH), Juane Canari (JC), Freeman cucumber (FC), Snakemelon (SM), and PI 124111] cultigens were used to determine the use of these markers for assessing genetic variation among and within populations of each species (outgroup = Cucumis metuliferus). RAPD and isozyme marker variation was related to previous taxonomic classification and available pedigree information. Although dendrograms derived from cluster analyses using species' variation at marker loci were dissimilar, these disparities were consistent with differences in the pedigrees and/or other information (e.g., morphological) known about each accession and species. Elite U.S. processing cucumbers (G421, GY-14a, and H-19) shared distinctive biochemical affinities. Doublon was differentiated from TM, GFH, and JC. Doublon had biochemical affinities with FC, SM, and PI 124111.
Melon PI 414723 Is Resistant to Papaya Ringspot Virus Watermelon Strain
Authors: McCreight James D.
Published: February 2019

PI 414723 has received much attention from melon (Cucumis melo L.) breeders, pathologists, and entomologists for resistances to zucchini yellow mosaic and watermelon mosaic viruses, including resistances to virus multiplication and subsequent transmission by the melon aphid, powdery mildew resistance, and melon aphid (Aphis gossypii Glover). PI 414723 was derived from PI 371795, which was a contaminant in cucumber (Cucumis sativus L.) PI 175111 collected in 1948 by Walter N. Koelz in Mussoorie, Uttar Pradesh, India (altitude 1829 m). Its fruit, which have soft flesh and rind that split at maturity, are used in soups and stews, and the seeds are roasted and eaten. PI 414723, PI 371795, and the related Ames 20219 and progeny 92528a were resistant to California and Florida isolates of papaya ringspot virus watermelon strain (PRSV-W). Plants were either symptomless, or they exhibited local lesions, systemic necrosis, or systemic spots. Resistance to PRSV-W is conditioned by a single dominant gene. Allelism with Prv1 (PI 180280, Rajkot, Gujarat, India), Prv2 (PI 180283, Bhavnagar, Gujarat, India), Nm (`Vedrantais, Fance), and a recently described gene for PRSV-W resistance in PI 124112 (Calcutta, India) is yet to be determined.
A Tendrilless Mutant in Watermelon: Phenotype and Development
Authors: Zhang Xingping , Rhodes Bill , Baird Vance , Skorupska Halina
Published: February 2019

A spontaneous watermelon mutant, previously named branch less, was re-evaluated in this study. The mutant watermelon plants from genetic stock Bl-91 and derived from F2 and BC1 populations, did not produce tendrils under field or greenhouse conditions. The mutants stopped producing branches after the fifth or sixth node. Leaf shape changed during development of the mutants. Early leaves were normal, but later leaves had fewer and fewer lobes, finally becoming triangular toward the end of the shoot. The most distinct effect of the mutant gene was to convert vegetative meristems into floral meristems; tendrils and axillary buds were replaced by flowers at the node. The mutant plants were determinate. A grafting experiment showed that the rootstock had no effect on the mutant phenotype. Genetic analysis of F1, F2, and BC1 populations suggested that the mutant is inherited as a single, recessive nuclear gene. Based on the phenotype, a new name is suggested for this mutant: tendrilless, with a new gene symbol tl.
Root System Characteristics of Young Papaya Plants
Authors: Marler Thomas E. , Discekici Haluk M.
Published: February 2019

Excavation of field-grown `Red Lady' and `Tainung #2' papaya plants was begun 3 months after transplanting to the field to characterize development of the papaya root system. The roots were separated into the taproot system and lateral roots within three size categories: <1, 1 to 5, and >5 mm. Length of the taproot system and the larger lateral roots was measured directly, and that of the smaller roots was determined using the line-intersect method. Mass of the various size categories was measured after drying at 70°C. A typical plant 3 months after field-planting was ≈ 60 cm tall and exhibited a root system radial spread of 34,636 cm2, total root length of 9613 cm, and total dry mass of 17.3 g. The taproot system accounted for >70% of the mass and <5% of the length of the root system. Lateral roots <1 mm in diameter accounted for <10% of the mass and >70% of the length of the root system. A typical plant during the heavy fruit set stage, about 6 months after field planting, was 175 cm tall and exhibited a root system radial spread of 101,736 cm2, total root length of 975 m, and total dry mass of 539 g. The taproot system accounted for ≈38% of the dry mass and <1% of the length of the root system. Lateral roots <1 mm in diameter accounted for ≈5% of the dry mass and 65% of the length of the root system. Plant age influenced root system characteristics more than cultivar, especially the proportional distribution of mass and length among the defined root classes.
Low-temperature, Controlled-atmosphere Storage of Tree-ripe `Keitt' Mangoes
Authors: Bender R.J. , Brecht J.K. , Huber D.J. , Sargent S.A.
Published: February 2019

Tree-ripe `Tommy Atkins' mangoes were not injured during storage in controlled atmospheres (CA) for 21 days at 8°C, and the fruit resumed ripening after transfer to air at 20°C (Bender et al., 1995). In our study, tree-ripe `Keitt' mangoes were stored at 5 and 8°C in either 10% or 25% CO2 combined with 5% O2 with control fruit maintained in air. Control fruit had higher percentages of electrolyte leakage than CO2-treated fruit at transfer from the CA and after 3 days in air at 20°C. Fruit stored in 25% CO2 at 5°C had significantly higher concentrations of 1-aminocyclopropane-1-carboxylic acid (ACC), over 0.5 nmol ACC/g fresh weight in mesocarp tissue. All the other treatments had similar ACC levels (<0.3 nmol/g fresh weight) after 21 days in CA. Ethylene production rates at both temperatures were significantly lower in the 10% CO2 treatment than in control fruit and were not detectable in 25% CO2. Ethylene production was similar in all treatments after transfer to air. Fruit from the 25% CO2 treatment at 5°C developed dull, green-grayish spots on the epidermis, but otherwise epidermal color, as determined by chroma and hue angles, did not differ among the treatments. There also were no differences in flesh color and flesh firmness.
Volatile Cuticular Components Involved in Superficial Scald
Authors: Wee S. , Beaudry R.M.
Published: February 2019

Autoxidation products alpha-farnesene of have been implicated in superficial scald induction for apple (Malus domestica cv. Cortland Apple) fruit. We suspect the apple cuticle acts as a sink where α-farnesene can accumulate and eventually autoxidize into hydroperoxides, conjugated trienes, 6-methyl-5-hepten-2-one (ketone), and other compounds. These oxidized byproducts may diffuse back into the peel, thereby initiating the scald process. Cortland apples were stored at 0.8°C. Volatile cuticular components were analyzed at 2-week intervals by gas chromatography–mass spectroscopy. Only two scald-related volatiles were found, 6-methyl-5-hepten-2-one and α-farnesene. The identification of these compounds may allow the determination of cuticular involvement in superficial scald, as well as a possible correlation between the volatiles and apple scald development. α-farnesene concentrations initially increased and was followed by a decline, possibly due to its autoxidation.
Intermittent Warming Effects on Superficial Scald of Apple Fruit
Authors: Alwan Thair F. , Watkins Christopher B.
Published: February 2019

Fruit of `Cortland', `Delicious' and `Law Rome' were warmed for 24 hours at 20°C either weekly, once every 2 weeks, or once every 3 weeks during storage. The effect of these treatments on fruit ripening and concentrations of alpha-farnesene and conjugated trienes in hexane extracts of the skin were measured during storage. Without warming, scald incidence of the cultivars was 70%, 14%, and 85%, respectively. Intermittent warming treatments resulted in a marked reduction of scald though effectiveness was affected by cultivar. In `Cortland', scald was reduced only by the weekly warming treatment (10%) as was less effective than DPA (1%). In `Delicious', all warming treatments were equally effective. In `Law Rome', weekly warming resulted in better control of scald (3%) than DPA (14%) and less frequent warming was proportionately less effective in controlling the disorder. Concentrations of conjugated trienes at 281 nm did not relate consistently to scald incidence after storage. However, ratios of conjugated trienes of 258 nm or 269 nm with 281 nm strongly support a hypothesis that non-toxic and toxic oxidation products of alpha-farnesene interact and influence the effectiveness of postharvest treatments on scald control (Du and Bramlage, 1993; JASHS 118:807-813). A hypothesis relating the interactions between ripening and scald development will be presented. Supported in part by USDA Specific Cooperative Agreement 58-1931-5-017.
Production Method and Irrigation Effects Postplanting Root Morphology of Quercus virginiana
Authors: Marshall Michael D. , Gilman Edward F.
Published: February 2019

Quercus virginiana trees were container-grown (CG) or field-grown (FG) to a mean trunk diameter of 9.4 cm (3.7 inches), transplanted into sandy soil, and established with frequent or periodic irrigation. Three years after transplanting, trees were harvested with a 1.5-m- (60-inch-) diameter tree spade. Root number and root cross-sectional area was evaluated at the periphery of the tree spade-dug root ball. Despite similar increases in trunk diameter, FG trees had greater root number and root cross-sectional area than CG trees. The increase in root cross-sectional area occurred for roots 5 to 20 mm in diameter at the 0- to 25-cm and 75- to 100-cm soil depths. Irrigation frequency after transplanting had no effect on root number in FG trees; however, root number in CG trees decreased without frequent irrigation.
Growth and Flowering of Garden Chrysanthemums Produced in Plastic or Copper-impregnated Fiber Containers
Authors: Ruter John M.
Published: February 2019

A study was conducted with Dendranthemum ×grandiflorum (Ramat.) Kitamura garden chrysanthemum (`Grenadine', `Nicole', and `Tolima') to evaluate the growth and flowering of these plants grown in 2.6-L (no. 1) black plastic containers compared to plants grown in fiber containers with Cu(OH)2 impregnated into the container walls. For all three cultivars, growth indices, shoot and root dry weights, and total biomass increased for plants grown in fiber containers. Total number of flower buds per plant increased 30% to 32% for `Grenadine' and `Nicole' and 53% for `Tolima' grown in fiber containers. Plants grown in Cu(OH)2-impregnated fiber containers had less root coverage at the container:growing medium interface and no observable root circling in contrast to visible root circling on plants grown in black plastic containers. Foliar nutrient analysis on `Grenadine' showed that K decreased and Fe and Cu increased when grown in Cu(OH)2-impregnated fiber containers. No visible nutrient abnormalities were seen in this study.
Container Spacing Increases Container Capture of overhead Irrigation as Application Efficiency Declines
Authors: Beeson Richard C. , Yeager Thomas H.
Published: February 2019

Ligustrum japonicum, Rhododendron indica `Southern Charm' and Viburnum odoratissimum in 10-L containers were placed in a square grid pattern and overhead irrigated using impact sprinklers (30.3 L/min). Plants were irrigated with 12.5 mm with containers touching and, at 5 cm spacings, up to 50 cm between containers. Irrigation water reaching container surfaces (percent capture) increased for all species as container spacing increased. However, the increase in percent capture did not increase irrigation application efficiency because the percent of production area covered by the containers declined as spacing increased. Application efficiency declined with each increase in spacing to a low of 7%. The effects of intraand inter-canopy interference are discussed.
Nitrogen Release Characteristics from Controlled-release Fertilizers
Authors: Cabrera Raul I.
Published: February 2019

Seven nursery grade (8- to 9-month duration), polymer-coated, controlled-release fertilizers (CRF) were topdressed or incorporated to a peat: sand: vermiculite medium to yield the same amount of N per container. The pots were uniformly irrigated with DI water every week. Leachates were collected and analyzed for N (ammonium plus nitrate) concentration. Two distinct N release (NR) patterns were observed over the 180-day experiment. Osmocote 18–6–12FS, Prokote-P 20–3–10, Osmocote 24–4–8HN, and Polyon 25–4–12 exhibited a NR pattern that closely followed changes in average daily ambient temperatures (AT) over the season. This relationship was curvilinear in nature, with NR being highly responsive to AT up to 25°C. Conversely, Osmocote 18–6–12, Nutricote 18–6–8 (270), and Woodace 20–4–12 showed a stable NR pattern over a wider range of AT, with NR rates 30% to 60% lower than those in the temperature-responsive CRF. Incorporation produced significantly higher cumulative N releases than topdressing but without effect on the actual pattern of NR over the season. Regardless of the N formulation in the CRF, >80% of the N recovered in the leachates was in the nitrate form.
Growing Potato Tubers in Space
Authors: Tibbitts T.W. , Croxdale J.G. , Brown C.S. , Wheeler R.M.
Published: February 2019

Leaf cuttings from 6-week-old potato plants were planted into the Astroculture flight unit for the STS-73 shuttle flight in Oct. 1995. Tubers developed in the axils of the five leaf cuttings during the 16-days in microgravity. The flight unit had a closed growth chamber maintained at 22°C, 82% relative humidity, 150 μmol·m–2·s–1 photosynthetic photon flux, and with carbon dioxide controlled during the light period to ≈400 μmol·mol–1 and exceeding 4000 μmol·mol–1 during the dark period. A controlled delivery system using a porous tube system in arcillite medium provided water to the cuttings. A camera mounted in the top of the chamber provided video images of the plants at 2-day intervals. The cuttings maintained good vitality for the first 12 days of the flight followed by senescence of the leaves. Tubers 1.5 cm in diameter and weighing 1.7 g were produced. The shape and size of the tubers, the internal cell arrangement, and the size range of the starch grains, were similar on cuttings developed in a control experiment on the ground. Also the concentrations of starch, sucrose, fructose, glucose, and total soluble protein in the cuttings from space were similar to the cuttings developed on the ground. The challenges in scheduling experiments in a space flight and in conducting comparison control experiments on the ground are discussed. Environment control variations associated with cabin pressure changes, venting requirements, and air sampling are reviewed.
Yield of Greenhouse Tomato with Constant or Intermittent Heating of the Root and Shoot
Authors: Gent M.P.N. , Ma Y.-Z.
Published: February 2019

Is intermittent heating of the root zone more beneficial than constant heating for production of greenhouse tomato (Lycopersicon esculentum Mill), with diurnal variation of air temperature (DIF)? Yields were compared with 14°C day/14°C night or 22°C day/6°C night minimum air temperatures, resulting in 5 and 14°C DIF. The root zone was unheated or was heated to 20°C constantly or for 6 hours in the day, or 6 hours in the night. The greenhouse tomato cultivars Buffalo and Caruso were transplanted in early and late March in 1994 and 1995. Averaged over both years and cultivars, the yield from early March planting with 14°C DIF was greater than with 5°C DIF, 6.6 and 6.1 kg/plant, respectively, due to an increase in weight per fruit and to earlier ripening. Root zone heat increased yield compared to no heat, due to a greater number of fruit. With 5°C DIF, yields with constant and intermittent root zone heat were similar. The yields were 5.4, 6.4, 6.2, and 6.2 kg/plant with none, day, night and constant heat, respectively. With 14°C DIF, there were larger differences in yield, 5.7, 7.0, 6.6, and 7.1 kg/plant with none, day, night and constant root zone heat, respectively. However, interactions between air and root heat regimes were not statistically significant. The yield from late March planting was greater with 14°C than with 5°C DIF, but root zone heat had no effect. Research supported in part by grant 93-37100-9101 from NRI Competitive grants program/USDA.
Geographical Influences on Morphological Variation in Rubus ursinus Subsp. macropetalus
Authors: Anderson Angela K. , Finn Chad E.
Published: February 2019

Morphological variation was examined in 20 populations of Rubus ursinus subsp. macropetalus from British Columbia, Washington, and Oregon grown in a common garden. There was significant variability between and within populations for most traits studied. Principal component analyses separated populations along geographical clines for traits of horticultural significance. PC1 represented a general vigor component in all trials, and formed a negative correlation with elevation in four of five analyses (r = 0.60, 0.58, 0.50, 0.49; P < 0.05). Autumn leaf senescence tended to increase from west to east and with elevation. With higher elevation, there was a tendency for fruit weight to decrease, for later vegetative budbreak and fruit ripening, and for a shorter budbreak to first flower interval. From north to south, budbreak became somewhat earlier, cane spot susceptibility decreased, and budbreak to first flower interval increased. Characterization of this species will assist breeders to identify possible sources of cold hardiness, disease resistance, improved vigor, and acceptable fruit traits for the improvement of cultivated trailing blackberry.
Primocane Flowering in Blueberry
Authors: Lyrene Paul
Published: February 2019

Cultivated blueberries (Vaccinium section Cyanococcus species, including lowbush, highbush, and rabbiteye) normally produce flower buds at the end of the growing season; these remain dormant during the winter and give rise to flowers the following spring. However, rabbiteye and low-chill highbush cultivars that are maintained in a state of vigorous growth throughout the winter in an unheated greenhouse in Gainesville in north Florida flower and produce fruit continuously on new growth throughout December, January, and February. The regimen of cool (but not freezing) nights and short, warm days permits the plants to continue growth throughout the winter and results in rapid conversion of newly-formed axillary buds into flower buds. These do not become dormant, but sprout to produce flowers and fruit almost as quickly as they are formed. Extending the photoperiod or raising night temperatures inhibits primocane flowering by allowing the axillary buds to remain vegetative. Primocane flowering, which occurs naturally in highbush blueberry production fields south of lat. 28°N in Florida and at lat. 30°S in eastern Australia, can contribute to an extended harvest season (4 to 8 months per year) from a single cultivar.
A History of the Ecuadorian Strawberry, Huachi (Ambato)
Authors: Hancock J.F. , Finn C.E. , Heider C.
Published: February 2019

Spaniards brought Fragaria chiloensis when they conquered Ecuador the mid-1700s. The `Fluachi' strawberry, which was developed from these plants, became renowned in Ecuador and was eventually produced or on 500 to 800 ha in the town of Huachi Grande near Ambato. This white-fruited, long, wedge-shaped strawberry is still praised for its firmness, flavor, aroma, and shipping quality. The fruit are produced year-round on plants grown on volcanic, sandy soils in a very dry environment at an ≈3000-m elevation near the equator. The USDA germplasm explorers Paopenoe and Darrow documented the production of the `Huachi' in the 1920s and 1950s and brought it to North America for breeding. Selections from seedling populations were determined to be red stele resistant and found their way into several Pacific Northwest cultivars, although the `Huachi' was eventually lost in North America. Recently, we traveled to Ecuador to re-collect `Huachi' and assess the strawberry industry there. Huachi is still grown commercially in Ecuador, although there are now only 4 to 5 ha remaining. Drought in the 1970s, “tired” soils, and the introduction of the more productive and easier to produce California cultivars have supplanted its cultivation. Ecuador now produces ≈350 ha of strawberries using California production systems. This fruit is exported fresh, primarily to the United Sates, or is frozen in a 4 + 1 sugar pack. We brought `Huachi' back for distribution to interested breeders and to set up fertilizer trials on an established field to try to boost its productivity.
Strawberry Cultivar Responses to Variations in Planting Time, Stock, and Mulches
Authors: Galletta G.J. , Enns J.M. , Maas J.L.
Published: February 2019

The cultivars Allstar, Honeoye, Kent, and Jewel yielded the most successful summer and subsequent spring crops when planted in mid-July from dormant, cold-stored, multiple-crowned, nursery mother plants. Summer fruit sizing during very high temperatures was a problem; fruit number and quality was not. In a second hot year, the same cultivars did not give satisfactory summer crops when planted after late July. The return spring crop was most successful following planting in July rather than August or September, though there was a significant cultivar × planting date interaction for a number of characters. Nursery mother plants were more productive than first daughter plants. `Tristar' outyielded `Seascape' on black poly-mulched beds but not on killed vetch sod beds. `Allstar' runnered freely and produced good crops on three types of raised bed killed sod mulches and on red, blue, and silver-painted black poly raised bed mulches. Compared to the summer-planted, black, poly-mulched standard, `Mohawk' had increased but later yields, when the poly was painted blue, red, or silver, and much later yields, when mulched with recycled paper or wood fiber. The silver and paper treatments depressed fruit size. The wood fiber mulch seems promising for deliberately delaying ripening by lowering soil temperatures under the mulch. Seedling and selection plantings have generally responded favorably to summer planting from potted or “plug” plant stocks on unfumigated soil, thus, shortening the selection and evaluation cycles, with accompanying savings in land, water, fertilizer, and pesticide use.
Cucumber Yield and Soil Nutrient Changes with Poultry Litter and Synthetic Fertilizers
Authors: Roberts Warren , Duthie Jim , Edelson Jonathan
Published: February 2019

Soils in eastern Oklahoma have low N and P levels. The poultry industry in the area produces large amounts of poultry litter. Horticultural producers could benefit from using the poultry litter as a fertilizer for various crops, but many horticultural crops require a fertilizer with a ratio of about 2:1:3 (N: P2O5: K2O). Poultry litter has an approximate ratio of 1:1:1. Poultry litter applied at a rate to supply all needed N or K will supply more P than is needed by the current crop, although low P soils can accumulate significant amounts of P before the P levels are excessive. Poultry litter at different rates and synthetic fertilizers have been applied for 3 years to a field in which cucumbers were produced. Poultry litter rates supplied N at as much as 500 kg·ha–1 and P2O5 at as much as 300 kg·ha–1. Cucumber yields were recorded, and soil tests were conducted three times a year for N, P, K, Ca, Mg, Mn, Cu, Pb, Zn, and Fe. Cucumber yields from plots fertilized with poultry litter were equal to or greater than yield from plots that received commercial fertilizer. There appears to be a trend toward increasing levels of soil P with all treatments. and decreasing levels of soil Zn with all treatments. After 3 years, there is no evidence of detrimental levels of any of the monitored elements.
Cover Crops and N Rates Influence Sweetpotato Production
Authors: Sanders D.C. , Hoyt G.D. , Gilsanz J.C. , Davis J.M. , Garrett J.T. , Decoteau D.R. , Dufault R.J. , Batal K.D.
Published: February 2019

`Jewel' sweetpotato was no-till planted into crimson clover, wheat, or winter fallow. Then N was applied at 0, 60, or 120 kg·ha–1 in three equal applications to a sandy loam soil. Each fall the cover crop and production crop residue were plowed into the soil, beds were formed, and cover crops were planted. Plant growth of sweetpotato and cover crops increased with N rate. For the first 2 years crimson clover did not provide enough N (90 kg·ha–1) to compensate for the need for inorganic N. By year 3, crimson clover did provide sufficient N to produce yields sufficient to compensate for crop production and organic matter decomposition. Soil samples were taken to a depth of 1 m at the time of planting of the cover crop and production crop. Cover crops retained the N and reduced N movement into the subsoil.
Quantitation of DNA of Propidium Iodide-stained Nuclei from Ipomoea Species and Sweetpotato Using DNA Flow Cytometry
Authors: Bohac J.R.
Published: February 2019

Sweetpotato, Ipomoea batatas is in the morning glory family, Convolvulaceae, genus Ipomoea, group Batatas. It has many wild Ipomoea relatives that serve as a reservoir of many needed pest and stress-resistance genes. A major barrier to introgression of useful genes is the ploidy gap—sweetpotato is a hexaploid and wild Ipomoeas are diploids and tetraploids. The wild species can be successfully crossed using 2n pollen or by first increasing ploidy by colchicine treatment. The ploidy of such hybrid offpsring can be determined by DNA flow cytometry. My objective was to develop a technique to determine DNA content in Ipomoea and values for DNA content for the major Ipomoea species using the EPIC flow cytometer with a UV detector. Nuclei were extracted and pretreated with cellulase and pectolyase before staining with propidium iodide (PI). A highly linear relationship was found between the DNA content determined by DNA flow cytometry and the ploidy of the closest sweetpotato relatives as determined by chromosome counts. These species were diploid I. trifida, tetraploid I. batatas, and hexaploid I. batatas. DNA content was most similar among other diploid Ipomoea species in the group Batatas and was significantly different in other Ipomoeas not in group Batatas.
Screening Sweetpotato Germplasm for Field Resistance to Scab (Sphaceloma batatas Saw.)
Authors: Mok Il-Gin
Published: February 2019

Field resistance to scab was assessed within Indonesian sweetpotato germplasm, and some of the CIP pathogen tested clones were also included. The total number of clones was 778 from Indonesia and 57 from the CIP pathogen tested list. Many of the clones tested were highly resistant under Indonesian field conditions. It was relatively easy to select resistant clones in Bogor and Lembang, West Java, Indonesia where high humidity is prevalent throughout the year. The proportion of resistant vs. susceptible accessions varied according to the geographical area of origin. The reaction to scab and the place of origin in the passport data were linked and compared for their percentage in each reaction category (e.g., HR, R, MR, S, and HS). The results indicated that there were two types of geographical provenance in terms of resistance reaction. The first group, categorized by the lower percentage (<10%) of HR clones, included West Java, Central Java, East Java, Bali, and West Sumatra. The second group, which had >15% of HR clones, included North Sumatra, Sulawesi, and Irian Jaya. When putting HR and R clones together, the first group had <30%, and the second >50%. This may be due to selection pressure exerted on the crop during the evolutionary process. Two hypotheses could be considered to explain this grouping. One is that the first group originated in areas where there has not been much natural selection pressure by the scab disease. The second hypothesis is that the grouping was enhanced by cultural practices of farmers (e.g., avoidance of cultivation during the rainy season). There are indications that most of the sweetpotatoes grown in the first group of provinces was produced on a commercial scale, while most of the crop in the second group of provinces was produced by subsistence farmers.
Inheritance of a Mild Reaction to Lettuce Mosaic
Authors: Ryder Edward J.
Published: February 2019

Resistance to lettuce mosaic (LMV) in current cultivars of lettuce is due to a single recessive gene, momo, in one of two allelic forms. The nature of the resistance may be described as resistance to multiplication and spread in the plant. Resistance is systemically manifested as small irregular yellowish areas on the leaf. This compares to the usual expression of susceptibility: vein clearing, followed by mottling, leaf margin recurving, and later stunting and yellowing. A cos-like stem lettuce from Egypt, `Balady Aswan', is susceptible to LMV, but reaction to the virus is a milder one than the usual susceptible reaction. Segregating generations from crosses with normal susceptible and resistant lines were analyzed. The data suggest a single gene for reaction type, with mild dominant or partially dominant to severe. Selection of lines from crosses with the resistant type allows the breeder to select resistant and mild alleles together, which confers a higher level of resistance than momo alone. Plants with the combined reaction either show no symptom or show the resistant symptom very late.
Optimizing Nitrogen for Improving Yield and Fruit Quality of `Redspur Delicious' Apple
Authors: Fallahi Esmaeil , Fellman John K.
Published: February 2019

Effects of three times and five rates of urea application on productivity, tree growth, soil nitrate movement, nutrient partitioning, and postharvest fruit quality of `Redspur Delicious' apple on M.7 rootstock over several years were studied. Time of application did not have significant effects on most fruit quality factors or yield. However, significant differences were observed for quality and yield measurements among different quantities of N. Fruit firmness decreased with every increment in N increase. Trees with N at 0.045 kg/tree had lower yield and higher fruit firmness than those with higher quantities of N. Fruit weight and color decreased with each increment increase in the quantity of N. Trees with N at 0.045 and 0.18 kg/tree had significantly better (more red) color and lower fruit N and leaf N than those with higher quantities of N. Bud tissue nutrients were affected by quantity of N application. Fruit from trees with N at <0.18 kg/tree had lower soluble solids. High N increased fruit ethylene and respiration. Nitrogen application affected 2-methyl butyl acetate of fruit. Monitoring nitrate movement through the soil showed that application of N at >0.45 kg/tree, particularly in fall resulted in excess levels of nitrate, increasing the possibility of underground water contamination. Applying N at ≤0.32 kg/tree did not result in excess soil nitrate at 1.52-m depth.
Fertigation of Young Apple Orchards
Authors: Stiles Warren C. , Robinson Terence L. , Reid W. Shaw
Published: February 2019

Experiments conducted since 1986 indicate that multi-nutrient fertigation may be effective in improving early growth and yield of new orchards. However, the early studies did not provide information concerning the contributions of individual nutrient elements to these responses. Experiments were established in 1993 and 1994 to compare effectiveness of alternative sources, rates, and methods of applying K, Zn, and Cu through drip irrigation compared with annual soil surface applications to `McIntosh'/M.9 and `Empire'/M.9 trees. After 3 years, leaf K, cumulative shoot growth, and first crop year yields were increased by application of K. Differences between sources, rates, times, or methods of application generally were not significant when relatively high rates were applied. However, early results from a rate study indicate a significant K source by rate interaction. Soil surface application of K plus drip irrigation appears to be comparable to fertigation in supplying this element. After 2 years, applying EDTA chelates of Zn and Cu through fertigation increased leaf Zn and Cu, respectively, but high rates required are considered to be uneconomical when compared with foliar sprays of these elements.
Local Soil Nitrogen Availability Affects Nitrate Uptake Capacity of Excised Peach Roots
Authors: Niederholzer F.J.A. , Weinbaum S.A. , DeJong T.M.
Published: February 2019

The interrelationships were studied between local soil N availability, tree N status, and uptake capacity of excised roots of mature, commercially grown `O'Henry' peach trees. Nitrogen sufficient (+N) and deficient (–N) peach trees were established previously by differential N fertilization. High (+N) and low (–N) soil microsites were established under +N and –N trees in June 1994. Per unit root length uptake capacities of roots excised from +N and –N microsites were measured in late July 1994. Root excised from +N microsites exhibited higher uptake capacity per unit root length than roots from –N microsites irrespective of tree N status. The relationship of these data to the concept that uptake is a function of sink N demand will be discussed.
Subcellular Localization of 14-3-3 Regulatory Proteins in Arabidopsis thaliana
Authors: Bihn Elizabeth A. , Ferl Robert J.
Published: February 2019

The 14-3-3 proteins were originally characterized in mammalian brains and were thought to be specifically involved in neurotransmitter production. Subsequent research has revealed that this family of proteins is ubiquitous in eucaryotic cells and is involved in a wide range of regulatory and signal transduction pathways. For instance, some 14-3-3 proteins have been associated with the signal transduction in response to fungal pathogen attack and to other environmental factors that affect transcription. In Arabidopsis, 10 isoforms of 14-3-3 have been isolated, raising the possibility that diversity of function may be governed by cellular and subcellular specificities of expression and localization. We have investigated the localization of certain 14-3-3 isoforms through transgenic expression of epitope-tagged 14-3-3s.
Differential Expression of ACC Synthase Genes in Response to Stress
Authors: Schlagnhaufer Carl D. , Arteca Richard N. , Pell Eva J.
Published: February 2019

Ethylene production is involved in many plant physiological processes including stress responses and is frequently associated with foliar senescence. Ethylene emission is a common plant response to many biotic and abiotic stresses. We have cloned two ACC synthase cDNAs (OIP-1, PAC-1) from the leaves of ozone treated Solanum tuberosum L. plants. Plants treated with ozone produced ethylene within 1 hour following treatment initiation. Levels continued to increase reaching a peak after 2 h. PAC-1 was expressed after 1 hour reaching a maximum by 2 hours and showed a marked decline after 4 h. OIP-1 was first expressed after 2 hours and high levels of expression continued up to 4 hours following treatment initiation. Leaves treated with CuCl2 produced high levels of ethylene within 0.5 hour after treatment initiation. Ethylene levels continued to increase reaching a peak after 2 hours with no change after 4 h. PAC-1 was expressed after 0.5 hour reaching a peak at 1 hour and showed a progressive decline from 2 to 4 h. However, OIP-1 expression was first detected 2 hours following treatment initiation and high levels of expression continued up 4 h. Leaves exposed to Alternaria solani produced increased levels of ethylene 1 day following inoculation reaching a peak after 3 days. PAC-1 was expressed at a low level 1 day after inoculation and expression remained constant for the duration of the experiment, whereas, OIP-1 was not expressed until day 4.
Cloning and Characterization of an ETR1 Homologous Gene from Carnation (Dianthus caryophyllus L. cv. `White Sim') Petals
Authors: Verlinden Sven , Woodson William R.
Published: February 2019

Ethylene plays a key regulatory role in carnation flower senescence. Flower senescence is associated with a significant increase in ethylene production. Continued perception of this ethylene by the flower is necessary to sustain the climacteric rise in ethylene and the expression of senescence related genes associated with senescence. In addition, increased sensitivity by the flower to ethylene during development and senescence has been observed. In order to study the perception of ethylene at the molecular level, an ethylene receptor gene was cloned from carnation petals. The clone, CARETR, shows 68% homology at the nucleic acid level with the Arabidopsis ethylene receptor gene, ETR1. Northern blot analysis revealed that CARETR is present as a low abundant transcript in petals, styles, and ovaries. Further analysis also showed that CARETR is upregulated during flower senescence. Treatment with the ethylene action inhibitor norbornadiene (NBD) resulted in decreased levels of CARETR transcripts. These data suggest that CARETR plays a role in the increased sensitivity of carnation flowers to ethylene during flower development and is involved in staging the rapid and orchestrated death of the flower.