bluuebunny/crossref_metadata_2025 huggingface dataset:
Ripening Behavior of `Columbia' and `Gebhard' Strains of Red `d'Anjou' Pears after Cold Storage
Authors: Chen Paul M. , Varga Diane M. , Mielke Eugene A.
Published: January 2019

`Columbia' and `Gebhard' strains of red `d'Anjou' pears (Pyrus Communis L.) harvested at similar maturity exhibited different ripening behavior after monthly removal from 1C storage in air. `Columbia' fruit produced ethylene at higher rates than `Gebhard' fruit during 15 days of ripening at 20C after each corresponding storage interval, `Gebhard' fruit required a longer period of chilling than `Columbia' fruit to generate noticeable rates of ethylene during ripening. The unripened fruit of both strains contained similar amounts of ACC at each corresponding storage interval. At each corresponding ripened state, ACC content in `Columbia' fruit increased 2 to 3-fold, while that in `Gebhard' fruit changed very little. After sufficient chilling, `Columbia' fruit were capable of softening to proper ripeness, and they developed buttery and juicy texture as indicated by the apparent reduction of extractable juice (EJ) content. `Gebhard' fruit also softened but to a lesser extent than `Columbia' fruit. Ripened `Gebhard' fruit had only slightly lower levels of EJ than unripened fruit and did not develop a buttery and juicy texture after any storage intervals. Titratable acidity (TA) in fruit of both strains varied between for the 1988 and 1989 seasons but decreased significantly during storage in both years. Soluble solids concentrations (SSC) in both strains also varied seasonally but did not change during storage or ripening. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Pepino Dulce (Solanum muricatum Ait.) Quality Characteristics Respond to Nitrogen Nutrition and Salinity
Authors: Pluda D. , Rabinowitch H.D. , Kafkafi U.
Published: January 2019

The effect of fertigation with N-NO3 at 3, 6, or 12 mmol·liter-1, and 0, 3, or 6 dS·m-1 chloride ions on fruit quality of three pepino dulce selections was studied. Genotypes varied considerably in their response to mineral treatments in most quality characteristics. Variation in fruit size was greatly reduced when clusters were thinned to three fruit. Increasing chloride concentration in the nutrient soltuion reduced fruit size significantly and ascorbic acid concentration relative to the control, but fruit shape was not affected. Increases in NaCl salt, but not N concentration, resulted in significantly higher soluble solids concentration (SSC) and firmness in all three genotypes. Electrical conductivity, acidity, and pH were significantly affected by the two mineral treatments in the first trial, but remained unchanged in the second season. Fruit firmness, SSC, and acidity declined by 12% to 30%, whereas ascorbic acid content increased during 14 days storage at room temperature. These changes depended on genotype and environment during fruit growth and development. Organoleptic ratings were highest in salt-treated plants. Fruit quality of pepino dulce may be manipulated by crop management, thus improving its acceptability in Western markets.
Quantitative and Qualitative Changes in Sugar Content of Peach Genotypes [Prunus persica (L.) Batsch.]
Authors: Brooks Sylvia J. , Moore James N. , Murphy J. Brad
Published: January 2019

Fruit of four clingstone peach [Prunus persica (L.) Batsch.] seedling populations, 54 advanced selections, and the cultivars Allgold and Goldilocks were analyzed for sugar content, soluble solids concentration (SSC), and acidity. Sucrose, glucose, fructose, and sorbitol were identified and quantified by high pressure liquid chromatography (HPLC) analysis. Variation was found for all the sugars between the seedling populations. Comparison of the means for the advanced selections with `Goldilocks' indicates that progress has already been made toward selection for a sweeter peach. Glucose, fructose, sorbitol, SSC, and acidity (citric) differed significantly for two harvest years, while sucrose and total sugar concentrations showed no significant yearly variation. A fruit maturity study revealed no significant changes in SSC, percentages of glucose, fructose, and total sugar during ripening on the tree. Acidity and percent sorbitol decreased, while the sugar: acid ratio and percent sucrose increased with increasing maturity. Broad-sense heritability of SSC, acidity, and sugar: acid ratio bad values >0.72, while values for individual sugars and total sugars were much lower. Transgressive segregation for each sugar was found in seedling populations.
Tomato Response to Starter Fertilizer, Polyethylene Mulch, and Level of Soil Phosphorus
Authors: Grubinger V.P. , Minotti P.L. , Wien H.C. , Turneti A.D.
Published: January 2019

Unmulched and polyethylene-mulched tomatoes (Lycopersicon esculentum Mill.) were grown with and without starter fertilizer (SF) in four field experiments. The fields varied as to residual P level and the amount of P incorporated before planting. No benefits from SF were obtained on a soil with high residual P that was moderately fertilized with P before transplanting or on a soil with low residual P that was heavily fertilized with P. A positive effect from SF was observed only when residual P was low and no P was broadcast, and this was true in mulched and umnulched plots. No significant SF by mulch interaction was obtained in these experiments even though mulching consistently increased shoot P concentrations and fruit yield. The mulch was beneficial even under conditions where unmulched tomato leaves contained 0.4 % P 3 weeks after transplanting, indicating that factors in addition to improved P nutrition are also involved in the mulch effect.
Chilling of Endodormant Peach Propagules: V. Comparisons between Seeds, Seedlings, and Cuttings
Authors: Frisby James W. , Seeley Schuyler D.
Published: January 2019

We determined whether the chilling process (endodormancy release) was similar in peach [Prunus persica (L.) Batch cv. Johnson Elberta] seeds, seedlings (near normal to physiologically dwarfed), and mature plants (cuttings) by comparing correlation coefficients of various growth measurements following similar chilling treatments. Seed germination (10 days after forcing at 20C) and seedling emergence (15 days after forcing in the greenhouse) correlated highly with leaf and shoot growth (56 days of growth) of seedlings and terminal shoot growth of cuttings (13 days after forcing). The correlations were higher for germination than for emergence. Initial (first season) seedling growth correlated poorly with germination, emergence, budbreak, and growth of seedlings (second season) and shoot growth of cuttings. Budbreak and growth of seedlings correlated highly with shoot growth of cuttings. The abnormal leaf problem, which can cause apex abortion (common with initial seedling growth), confounded correlations with initial seedling growth. Yet, the abnormal leaf problem did not hinder correlations with the second seasons growth. Good relationships between the chilling mechanisms that promoted germination, emergence, budbreak, and growth of seedlings and shoot growth of cuttings existed, but were dependent on what was measured and when the measurement was taken. Germination (forced at 20C) was the most accurate indicator of the seed chilling status for comparisons with the responses of the other propagules.
Water Relations of a Fragaria chiloensis and a F. virginiana Selection during and After Water Deficit Stress
Authors: Zhang Baolin , Archbold Douglas D.
Published: January 2019

A comparative study was performed to elucidate changes in the water relations of Fragaria chiloensis (L.) Duch. `BSP14' (FC) and F. virginiana (L.) Duch. `NCC85-13V' (FV), grown in containers in a greenhouse, in response to imposed water deficit stress and subsequent recovery. At incipient wilting, a reduction in osmotic potential at full turgor (Ψπ100 of 0.42 MPa occurred in leaves of FC, while no change was found in FV. Leaf water potential (Ψ) isotherms revealed that as leaf Ψ and relative water content (RWC) declined, stressed FC plants maintained a higher turgor potential (ΨP) and lower osmotic potential (Ψπ) than nonstressed (control) plants, while there was no effect of drought stress on these relationships in the FV plants. From the isotherms, turgor loss was estimated to occur at a lower leaf Ψ and RWC in stressed FC plants than either in control FC plants or stressed and control FV plants. During a diurnal phase 36 hours after wilting, leaf Ψ, Ψπ and RWC of the FC selection were generally lower in stressed than in control plants, with differences ranging from 0.14 to 0.74 MPa, 0.28 to 0.47 MPa, and 1% to 8%, respectively. In the FV selection, Ψπ was 0.09 to 0.31 MPa lower in stressed than in control leaves, while the other characteristics were not affected. Leaf ΨP, of stressed FC plants was 0.09 to 0.27 MPa higher than controls during the dark period, but was similar during the day. When plants of both species were grown and stressed in the same container, FV plants wilted ≈4 days earlier than FC plants, and foliar Ψπ100 of FC was 0.35 MPa lower than that of FV at incipient wilting. The isothermal relationships between leaf Ψ and Ψπ100 indicated FC had a Ψπ100 ≈ 0.25 MPa lower than FV at a Ψ <1.5 MPa. This study provided evidence for greater osmotic adjustment in response to imposed water deficit stress in a selection of F. chiloensis than in one of F. virginiana.
Floral Ontogeny and Sex Determination in Monoecious-type Persimmons
Authors: Yonemori K. , Sugiura A. , Tanaka K. , Kameda K.
Published: January 2019

Patterns of floral differentiation were studied in two monoecious-type Japanese persimmon (Diospyros kaki L.) cultivars Hana-gosho and Kakiyama-gaki. In both cultivars, the pistillate and staminate floral primordium started to differentiate in early June, and differentiation progressed until August, when the sepal primordia in pistillate flowers and petal primordia of staminate flowers had become evident. The buds then entered a quiescent, overwintering state. Thus, flower sex of monoecious-type persimmons was determined at a relatively early stage of floral development. Moreover, in both cultivars, sex differentiation was associated with previous history of the current season's shoots. Current season's shoots that bore pistillate flowers differentiated pistillate buds (mixed buds from which pistillate flowers emerge) at significantly higher rates than for shoots that bore staminate flowers. Similarly, shoots that bore staminate flowers produced staminate buds (mixed buds from which staminate flowers emerge) at a higher percentage than shoots that had borne pistillate flowers. With `Hana-gosho', the flower type was also predictable with fair accuracy by bud position on the current season's shoot, i.e., pistillate flowers emerged from distal mixed buds, whereas staminate flowers arose predominantly from basal buds.
Comparison of Statistical Methods to Assess Yield Stability in Sweetpotato
Authors: Ngeve J.M. , Bouwkamp J.C.
Published: January 2019

Twenty-seven trials were conducted with 20 sweetpotato [Ipomoea batatas (L.) Lam.] clones in seven locations over 4 years in Cameroon to provide data for the evaluation of statistical methods appropriate for assessing yield stability. Four stability assessment methods were used. Clones 048, TIb 1, 1639, TIS 2498, and TIS 2544 were identified as stable for storage root yield by all four methods. The Eberhart and Russell and Perkins and Jinks methods are statistically related, each detected 9, 8, 9, and 10 clones as stable for total yield, marketable yield, and total and marketable root counts, respectively. Some clones considered stable for yield were found to be unstable for root counts. This result suggests that stability of a complex trait (such as yield) may not depend on stability of component traits. The Shukla method and the Francis and Kannenberg method were considered to be the most effective and useful of those tested. The Shukla method found more clones to be stable; also, the very high-yielding and very low-yielding clones were judged to be unstable. The Francis and Kannenburg method was very convenient, easy to use, and was appropriate for grouping clones of greater and lesser desirability and stability.
Tree Growth, Yield, and Fruit Quality of Ortanique Tangor on Eleven Rootstocks in Cyprus
Authors: Gregoriou C. , Economides C.V.
Published: January 2019

Growth, yield, and fruit quality were recorded for Ortanique tangor (Citrus reticulata Blanco) on 11 rootstocks until the trees were 12 years old. Trees on Volkameriana (C. volkameriana Pasq.), rough lemon, and `Estes rough lemon (C. jambhiri Lush.) were more productive per unit of tree size, and their cumulative yields per tree were significantly higher than those of trees on the other rootstocks. There was no significant difference between cumulative yields of Ortanique on the following rootstocks: sour orange (C. aurantium L.), `Palestine' sweet lime (C. limettioides Tan.), `Red' rough lemon (C. jambhiri Lush.), Rangpur (C. limonia Osbeck), and Amblycarpa (C. limonellus var. amblycarpa Hassk.). However, yield on these rootstocks was significantly higher than on Carrizo and Troyer citranges [C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.] and `Swingle' citrumelo [C. paradisi Macf. × P. trifoliata (L.) Raf.]. The high productivity per unit of tree size of `Palestine' sweet lime suggested that this rootstock could be used advantageously in closely spaced plantings. Rootstocks affected fruit size, weight, rind thickness, juice content, total soluble solids concentration (SSC), and total acids, but the differences were not large enough to be of practical importance.
Nitrogen Supply during Greenhouse Transplant Production Affects Subsequent Tomato Root Growth in the Field
Authors: Liptay A. , Nicholls S.
Published: January 2019

Tomato transplant (Lycopersicon esculentum Mill.) root growth in the field was directly related to N level supplied to the transplants as seedlings in the greenhouse. Root growth in the field increased exponentially when N was applied at 50 to 350 mg·liter-1. Transplant growth in multicelled trays increased in a sigmoidal fashion with N, up to 200 mg-liter'. The optimal N range for maximum survival, growth, and early yield in the field was from 100 to 200 mg-liter'. Strength of the seedling stem increased with N level curvilinearly. Seedling survival in the field was highly correlated with seedling stem strength.
Heritability and Phenotypic Correlations of Six Pecan Nut Characteristics
Authors: Thompson T.E. , Baker J.F.
Published: January 2019

Heritability estimates for pecan [Carya illinoinensis (Wangenh.) K. Koch] nut weight, nut buoyancy, nut volume, nut density, kernel weight, and percentage kernel were determined from 8748 nut samples representing 152 families collected during 25 years in the U.S. Dept. of Agriculture (USDA) pecan breeding program at Brownwood, Texas. Measurements were corrected for year-to-year environmental variability using least-squares constants of individual year effects. Adjusted values were then regressed on midparent means. Generally, heritability (h2) estimates were low to moderate: nut weight 0.35, nut buoyancy 0.18, nut volume 0.35, nut density 0.03, kernel weight 0.38, and percentage kernel 0.32. The low values are probably due to the extreme alternate bearing tendency of this species, since crop load affects pecan nut characteristics so directly. Phenotypic correlations among these traits showed that larger or heavier nuts had significantly higher kernel weight, buoyancy, and percentage kernel. Nut density increased with higher nut and kernel weight, but decreased with nut volume.
Respiratory Activity and Mitochondrial Oxidative Capacity of Bell Pepper Fruit following Storage under Low-oxygen Atmosphere
Authors: Rahman Abd-Shukor A. , Huber Donald J. , Brecht Jeffrey K.
Published: January 2019

Bell pepper (Capsicum annuum L., var. `Jupiter') fruit stored in 1.5%, 5%, or 10% O2, or in air at 20C for24 hours were compared to determine the residual effect of low-O, storage on respiration after transfer to air. The lowest O2 concentration (1.5%) exerted the greatest residual effect on bell pepper fruit CO2 production and O2, uptake. No ethanol was detected in the headspace gas of fruit stored in 1.5% O2. Carbon dioxide production continued to be suppressed for ≈ 24 hours after transfer from 1.5% O2 to air. Exposure to 5% O2, for 24 hours resulted in less suppression of CO, production and O2 uptake upon transfer to air, while 10% O2 exerted no residual effect. Extending the storage period in 1.5% O2 to 72 hours extended the residual effect from 24 to 48 hours. Ethylene production was not affected by storage in 1.5% or 4% O2 for 24 or 72 hours. The residual effect exhibited in whole fruit was not apparent in mitochondria isolated from bell pepper stored in 1.5% or 4% O2.
Morphological and Physiological Changes during Maturation of New Mexican Type Peppers
Authors: Biles Charles Lee , Wall Marisa M. , Blackstone Kevin
Published: January 2019

New Mexican Chile peppers (Capsicum annuum L. `New Mexico 6-4') were harvested at weekly intervals beginning 20 days after flowering (DAF), and were evaluated for ethylene (C2 H4) production, respiration rates, chlorophyll content, degradative enzyme activity (cellulase, polygalacturonase, ß-galactosidase), and fruit firmness. Morphological and physiological changes were most apparent in peppers harvested 54 to 69 DAF. ß-galactosidase activity increased rapidly beginning 54 DAF and reached a peak by 89 DAF. Fruit firmness was highest (36 newtons) at 54 DAF and had decreased significantly by 69 DAF. Carbon dioxide production and chlorophyll content were highest in young pods harvested 20 DAF and decreased steadily thereafter. A climacteric increase of CO, was absent. There were two peaks in C2 H4 production: one associated with rapid fruit growth and the other with color change (61 to 69 DAF). Fruit harvested on the same day but at different developmental stages (green to red) were similar to those observed in fruit harvested over the season for the physiological characteristics tested. Separation of pepper fruit soluble proteins on SDS-PAGE demonstrated increased intensity in protein bands at 27, 35, and 40 kDa and decreased intensity of 51 kDa band as the fruit matured. Several biochemical processes appeared to be enhanced in Chile pepper fruit from 47 to 69 DAF.
Resistance to Beet Armyworm, Hemipterans, and Liriomyza spp. in Lycopersicon Accessions
Authors: Eigenbrode Sanford D. , Trumble John T. , Jones Richard A.
Published: January 2019

Accessions of Lycopersicon esculentum var. cerasiforme (Dun.) A. Gray (cer) and L. pimpinellifolium (Jusl.) Mill. (pimp), sustained significantly less damage to fruit by beet armyworm [Spodoptera exigua (Hiibner)] than standard cultivars and breeding lines of L. esculentum Mill. (esc) under natural infestations in 1990 and 1991 in southern California. The dwarf vine cherry cultivar Tiny Tim also sustained less damage than the standards. Accessions of esc with various monogenic mutations sustained at least as much beet armyworm damage as did standard cultivars. The percentage of fruit damaged was significantly correlated with vine weight, weight per fruit, number of fruit, and the fruit-foliage weight ratio (Pearson's coefficients, respectively: -0.533, 0.450, -0.483, 0.390, n = 37). In laboratory assays, survival of beet armyworm was significantly lower (5% of susceptible& growth rates were significantly lower, and development time was significantly longer on the fruit of resistant `Tiny Tim' and LA 1320 cer than the fruit of 11 other test lines. There were no substantial differences in beet armyworm survival on the foliage of the test lines. In the field trials, there were also significant differences among the test lines in damage by Liriomyza species and hemipteran pests. Lines with genes for increased densities of nonglandular leaf trichomes (especially LA 1663) were generally less damaged by Liriomyza than other lines. Damage by hemipterans was correlated with vine and fruit size, fruit count, and fruit-foliage weight ratio in 1991, but high intraseason variability prevented clear identification of test lines resistant to these pests.
Benzyladenine and Other Chemicals for Thinning `Empire' Apple Trees
Authors: Elfving D.C. , Cline R.A.
Published: January 2019

Postbloom applications of benzyladenine (BA) thinned young fruitlets of mature `Empire' apple trees (Malus domestica Borkh.) as well as or better than NAA or carbaryl (CB). BA increased fruit weight more effectively than either NAA or CB. Promalin (PR) was less effective than BA for both thinning and fruit-weight increase. In 1990, both BA and PR reduced fruit set up to 29 days after full bloom, but PR showed less thinning activity. BA and NAA produced independent and additive thinning responses when tank-mixed. Effects of all thinners on foliar mineral-nutrient concentrations were associated with changes in fruit load. BA increased return bloom as much or more than NAA or CB. PR did not affect return bloom. Chemical names used: N -(phenylmethyl)-1 H -purine-6-amine [benzyladenine (BA)]; BA plus gibberellins A, and A, [Promalin (PR)]; 1-naphthaleneacetic acid (NAA); 1-naphthalenyl methylcarbamate [carbaryl (CB)].
Potential of Non-chemical Control Strategies for Reduction of Soil Insect Damage in Sweetpotato
Authors: Schalk J.M. , Bohac J.R. , Dukes P.D. , Martin W.R.
Published: January 2019

This 2-year study was conducted to determine if soil insect damage could be reduced in sweetpotato [Ipomoea batatas (L.) Lam] by treatment with an insecticide (fonofos) and/or a parasitic nematode (Steinernema carpocapsae Weiser), in conjunction with sweetpotato cultivars that differed in susceptibility to soil insect damage. Analysis of field data for the first year showed that the parasitic nematode provided significant damage protection of sweetpotato from wireworms (Conoderus spp.), Diabrotica sp., Systena sp., and sweetpotato flea beetle (Chaetocnema confinis Crotch), but not from grubs (Plectris aliena Chapin; Phyllophaga ephilida Say). In this same test, fonofos used alone provided protection against wireworm-Diabrotica-Systena (WDS complex) damage. In the second test, the nematode did not provide soil insect protection for the WDS complex, but fonofos did reduce damage for these insects. Poor efficacy in the second test with the nematode probably was due to high rainfall, which saturated the soil. Resistant cultivars provided good protection for all three categories of damage. When used with the insect-susceptible check `SC 1149-19', the nematode or fonofos treatments provided better control for all insect categories in the first test. In both years, much higher control of damage by all insect classes was achieved by the use of resistant cultivars in combination with the nematode and/or fonofos treatment (64% higher crop protection than the susceptible check line). Chemical name used: O-ethyl-S-phenylethylphosphonodithioate [fonofos (Dyfonate 10G)].
Ethylene Binding Site Affinity in Ripening Apples
Authors: Blankenship Sylvia M. , Sisler Edward C.
Published: January 2019

Scatchard plots for ethylene binding in apples (Malus domestica Borkh.), which were harvested weekly for 5 weeks to include the ethylene climacteric rise, showed C50 values (concentration of ethylene needed to occupy 50% of the ethylene binding sites) of 0.10, 0.11, 0.34, 0.40, and 0.57 μl ethylene/liter-1, respectively, for each of the 5 weeks. Higher ethylene concentrations were required to saturate the binding sites during the climacteric rise than at other times. Diffusion of 14C-ethylene from the binding sites was curvilinear and did not show any indication of multiple binding sites. Ethylene was not metabolized by apple tissue.
Mechanical Injury during Postharvest Handling of `Solo' Papaya Fruit
Authors: Quintana Maria Eloisa G. , Paull Robert E.
Published: January 2019

`Solo' papaya (Carica papaya L.) fruit removed at different points from a commercial packing house showed that skin injury due to mechanical damage increased as fruit moved through the handling system. The occurrence of “green islands” -areas of skin that remain green and sunken when the fruit was fully ripe-apparently were induced by mechanical injury. Skin injury was seen in fruit samples in contact with the sides of field bins, but not in fruit taken from the center of the bins. Bruise-free fruit at different stages of ripeness (5% to 50% yellow) were dropped from heights of 0 to 100 cm onto a smooth steel plate to simulate drops and injury incurred during commercial handling. No skin injury occurred, although riper fruit showed internal injury when dropped from higher than 75 cm. Fruit (10% to 15% yellow) dropped onto sandpaper from a height of 10 cm had skin injury symptoms similar to those seen on fruit from the commercial handling system. These results suggest that abrasion and puncture injury were more important than impact injury for papaya fruit. Heating fruit at 48C for ≈6 hours or until fruit core temperature (FCT) reached 47.5C aggravated the severity of skin injury. Delays in the application of heat treatment from dropping did not reduce the severity of skin injury significantly, except for fruit heated 24 hours after dropping. Waxing fruit alleviated the severity of skin injury, whether applied before or after the heat treatment. Skin injury to papaya was caused by abrasion and puncture damage-not impact-and increased during postharvest handling of the fruit. The injury was associated mainly with fruit hitting the walls of wooden bins-bin liners may reduce this injury.
States of Water in Summer-dormant Apple Buds Determined by Proton Magnetic Resonance Imaging
Authors: Liu Dehua , Faust Miklos , Millard Merle M. , Line Michael J. , Stutte Gary W.
Published: January 2019

Magnetic resonance imaging was used to determine water states in paradormant apple (Malus domestica Borkh.) buds and during early events when buds resumed growth. Proton density and states of water were determined by creating image maps of proton density and relaxation times (T2). Summer-dormant (paradormant) buds had T2 relaxation times up to 30 ms. This water in bud tissues is considered relatively free compared to water that had T2 relaxation times of <1 ms in other parts of the stem and bark. Buds were forced to grow either by pruning off the terminal bud or by starting the bud with thidiazuron (TDZ). Both treatments gave essentially the same results. After treatment, buds started to grow immediately and water moved into the stem and into the bud. As there was more free water in the bud, T2 values ranged up to 50 ms. There appeared to be an inhibitory gradient down on the shoot, which was removed temporarily by excising the top bud. However, between the 2nd and 10th day after removal of the top bud this dominance was reinstated by the highest bud on the stem, which eventually formed a shoot. TDZ treatment overcame this inhibitory gradient effect. There was also a growth potential gradient coinciding with the inhibitory gradient. The growth of lower buds was much slower than that of the upper buds. The growth potential gradient was not overcome by TDZ treatments.
Characteristics of Carbohydrate Metabolism in Sweet Corn (sugary-1) Endosperms
Authors: Doehlert Douglas C. , Kuo Tsung Min , Juvik John A. , Beers Eric P. , Duke Stanley H.
Published: January 2019

Metabolic characteristics of developing sugary-l maize (Zea mays L.) endosperms were investigated. In the later stages of development (>30 days postpollination), sugary-1 kernels maintained higher levels of many enzyme activities and retained more moisture than normal kernels. Higher enzyme activities were attributed to moisture retention and were not associated with any increase in dry weight accumulation. Of enzyme activities measured at 20 days postpollination, that of ADP-glucose pyrophosphorylase was higher in sugary-1 kernels than in normal, whereas total amylase, a-amylase, and pullulanase activities were lower. Experiments testing the effects of zero, one, two, and three doses of the sugary-1 gene in OH43 endosperms indicated that the sugary-1 phenotype was not expressed until three doses of the sugary-1 gene were present. Decreased activities of amylases, but not of pullulanase, were attributed to an interference in detection by phytoglycogen. Increased ADP-glucose pyrophosphorylase activity is attributed to a response by the maize endosperm cells to increased sucrose concentrations.
Apple Tree Performance with Mechanical Hedging or Root Pruning in Intensive Orchards
Authors: Ferree David C. , Rhodus W. Timothy
Published: January 2019

Annual mechanical hedging in August or root pruning at bloom was used to control the growth of four apple (Malus domestica Borkh.) cultivars in two orchard systems planted at half the recommended in-row spacing. Trunk cross-sectional area (TCA) per hectare on the trellis system was 30% higher, a result that correlated (r = 0.80) to a 40% higher cumulative yield per hectare over 10 years compared to the central leader system. Over 10 years, the cumulative yield and TCA per hectare of `Smoothee Golden Delicious', `Empire', and `Redchief Delicious' were higher in the trellis than the central leader system, while these characteristics of `Lawspur Rome Beauty' were not influenced by orchard system. `Lawspur' had the highest TCA per hectare, cumulative yield per hectare, and greatest tendency toward biennial bearing of the four cultivars. Root pruning reduced all tree-size measurements, while hedging did not influence tree height or average shoot length. Yield and yield per TCA were reduced by hedging and root pruning, with the greatest reduction in yield caused by root pruning. Hedging increased cumulative yield per hectare with root-pruned trees intermediate between hedged standard-spaced trees. Trellis trees had a higher density of spurs and shoots and a higher leaf area index than trees on the central leader system. An evaluation of the treatment combinations using net present value analysis indicated that none of the treatments was a profitable investment. Of the top twelve treatments, as evaluated for 10 years, nine were the central leader and three the trellis system, with none of the trellis and only four of the central leader treatments being hedged or root-pruned. Results of this study indicate that orchard intensification is accomplished best by choosing appropriate planting distances and not by attempting to control growth mechanically on trees planted too close for optimum performance.
Spacing and Pruning Affect Growth, Yield, and Economic Returns of Staked Fresh-market Tomatoes
Authors: Davis Jeanine M. , Estes Edmund A.
Published: January 2019

Unstable prices and increased competitive market pressures have caused many staked-tomato (Lycopersicon esculentum Mill.) producers to reexamine the costs and benefits of various production practices. In 1988 and 1989, field studies were conducted to determine if changes in plant in-row spacing and pruning could reduce production costs, increase yields, and improve grower net returns of staked `Mountain Pride' tomatoes. In both years, early-season yields were highest using early pruning (when lateral shoots were 5 to 10 cm long) or delayed pruning (when lateral shoots were 30 to 36 cm long) and in-row spacings ≤46 cm. In 1988, total-season yields per hectare of pruned plants increased as in-row spacing decreased. For nonpruned plants, however, total-season yields were high at all spacings. In 1989, total-season yields were lower from delayed-pruned plants than from nonpruned plants and there was little yield difference due to in-row spacing. In both years, nonpruned plants produced low yields of fruit >72 mm in diameter but their total yields were greater than those of pruned plants. Net returns per hectare, calculated from combined data of both years, were highest when 1) plants spaced closely in-row were pruned early and 2) plants were spaced 46 to 76 cm apart and either pruned early or not pruned.
Irrigation Cut-off Date Affects Growth, Frost Damage, and Yield of Jojoba
Authors: Nelson John M. , Palzkill David A. , Bartels Paul G.
Published: January 2019

Flower bud injury resulting from freezing temperatures has been a major problem in jojoba [Simmondsia chinensis (Link) C. Schneid.] production. A 3-year field study, which began with 4-year-old plants, evaluated the effect of three irrigation treatments on growth, flower bud survival, seed yield, seed weight, and seed wax concentration of six clones. After 3 years, irrigation cut-off dates of late May (dry treatment) and early September (medium treatment) resulted in reduced plant height and width compared to irrigating through November (wet treatment). Flower bud survival and seed yields were very low in the first year for all treatments. In the second and third years, bud survival for most clones, even at -8C, was greatly improved by withholding water in the fall. In December of the second and third years, plants in the medium and dry plots had lower leaf water potential than those in the wet plot. In the second year, plants in the medium and dry plots had seed yields that were 3.5 times higher and wax yields that were were 2.3 times higher than plants in the wet plot. In the third year, the medium treatment had the highest seed and wax yields. Average seed weight and seed wax concentration were generally highest for plants in the wet plot where seed yields were low. Withholding irrigation from jojoba in the fall appears to improve flower bud survival and seed and wax yields following cold winters.
Interaction of Shoot Emergence Date and Long Days after Controlled-temperature forcing of `Nellie White' Easter Lilies
Authors: Dole John M.
Published: January 2019

`Nellie White' Easter lily bulbs (Lilium longiflorum Thunb.) were given 6 weeks of 5.5C, placed in the greenhouse, and divided into groups based on number of days to emergence: 0 to 6, 7 to 13, 14 to 20, or 21 to 27 days. At emergence, the shoots received 0, 1, 2, or 3 weeks of long days (LDs). The experiment was repeated for 3 consecutive years. Late-emerging plants had fewer days from emergence to visible bud and anthesis than early-emerging plants. Consequently, late-emerging plants flowered within 3 to 11 days of early emerging plants despite 16 to 22 days difference in emergence time. Late-emerging plants were tallest, while plants emerging in the second week had the most leaves. Flower count was not influenced by emergence date in Year 1. In Year 2, flower count decreased curvilinearly with later emergence. In Year 3, flower count was highest in plants emerging in the second week and lowest in the last week. Increasing LDs decreased the number of days from emergence to visible bud and anthesis but increased plant height. LDs did not affect leaf count in any year or flower count in Years 1 and 2. In Year 3, flower count increased with increasing weeks of LDs. LD × emergence date interactions existed, but varied from year to year.
Modeling Leaf Development of the African Violet (Saintpaulia ionantha Wendl.)
Authors: Faust James E. , Heins Royal D.
Published: January 2019

Leaf unfolding rate (LUR) was determined for `Utah' African violet plants grown in growth chambers under 20 combinations of temperature and photosynthetic photon flus (PPF). A nonlinear model was used to predict LUR as a function of shoot temperature and daily integrated PPF. The maximum predicted LUR was 0.27 leaves/day, which occurred at 25C and a daily integrated PPF of 10 mol/m2 per day. The optimum temperature for leaf unfolding decreased to 23C, and the maximum rate decreased to 0.18 leaves/day as the daily integrated PPF decreased from 10 to 1 mol/m2 per day. A greenhouse experiment using 12 combinations of air temperature and daily integrated PPF was conducted to validate the LUR model. Plant temperatures used in the model predicted leaf development more accurately than did air temperatures, but using average hourly temperature data was no more accurate than using average daily temperature data.
Benefits of Progressively Increasing Container Size during Nursery Production Depend on Fertilizer Regime and Species
Authors: Beeson R.C.
Published: January 2019

Rooted photinia (Photinia ×fraseri) cuttings and hare-root slash pine (Pinus elliottii Engelm.) seedlings were transplanted initially into 0.9-, 2.9-, and 10.2-liter containers. A subset of these plants was transplanted from 0.9- and 2.9-liter containers into the next larger container size in the series (upcanning) until representative plants of each initial container size were growing in 10.2-liter containers. The photinia experiment was conducted with two fertilizer regimes [soluble vs. controlled-release (CR) fertilizer] superimposed. When CR fertilizer was used, upcanning from 2.9- to 10.2-liter containers produced the largest photinia. However, for pine, there was no advantage due to upcanning. When soluble fertilizer was used, photinia initially transplanted into 0.9-liter containers and upcanned to 2.9- and then to 10.2-liter containers had superior growth compared to those of other fertilizer × container combinations. Upcanning generally maintained or increased plant growth rate, while growth rates of plants kept in the same container generally declined the second season. Improved efficiency of the root system in nutrient absorption of upcanned plants is proposed as the mechanism for this response.
Computer Simulation of Volume Shrinkage after Mixing Container Media Components
Authors: Burés Silvia , Pokorny Franklin A. , Landau David P. , Ferrenberg Alan M.
Published: January 2019

A FORTRAN computer program was developed to simulate packing of spherical particles via a Monte Carlo procedure. Shrinkage in volume upon mixing different particle sizes was studied and simulated results were compared with experimental data. Maximum experimental shrinkage was obtained when the proportion of coarse particles of pine bark and sand mixtures ranged from 50% to 70% of the volume. Experimental shrinkage of a mixture of coarse and fine sand was closely reproduced by means of simulation. Particle size distribution appears to be the most important factor in relation to shrinkage and also in the establishment of relationships between the simulated and the experimental system.
Pungency and Sugars of Short-day Onions as Affected by Sulfur Nutrition
Authors: Randle W.M. , Bussard M.L.
Published: January 2019

Sixteen short-day onion (Allium cepa L.) cultivars with high (4.0 meq·liter-1) and low S (0.1 meq·liter-1) fertility were evaluated for several characteristics associated with bulb flavor. Sulfur levels interacted with cultivars in influencing bulb pungency and concentrations of S and individual sugars, except for fructose. Enzymatically formed pyruvic acid correlated poorly with bulb S concentration, which suggests differential partitioning of S into flavor and nonflavor compounds among cultivars. Bulb percent dry weight correlated negatively with bulb S concentration. Since poor correlations were found between enzymatically formed pyruvic acid and water-soluble carbohydrates, we postulate that pungency and sweetness function independently in bulbs of fresh-market short-day onion cultivars.
Ripening Stage Affects the Chilling Sensitivity of Greenhouse-grown Peppers
Authors: Lin W.C. , Hall J.W. , Saltveit M.E.
Published: January 2019

Greenhouse-grown `Bison' and `Doria' peppers (Capsicum annuum L.) were harvested when mature green (MG) (>95% surface green) or ripe (>95% of surface red or yellow). Both cultivars responded similarly to temperature and neither exhibited chilling injury (CI), as indicated by surface pitting, after storage at 13C for 1 or 2 weeks. Ripe peppers showed no CI when held at 1C for 1 or 2 weeks, while MG peppers exhibited CI after these treatments. Exposing MG peppers to 1C for 3 days caused CI and stimulated C2H4 (12.3x) and CO2 production (2.5x). In contrast, a similar exposure of ripe peppers did not cause CI but stimulated C2H4 (6.5x) and CO2 production (1.4x). It seems that CO2 and C2H4 production was stimulated by exposure to 1C, not necessarily by CI development. Our data question the physiological significance of elevated CO2 and C2H4 production in CI development. The observed tolerance of ripe peppers to 1C suggests that ripe greenhouse-grown peppers can be stored at temperatures lower than those currently recommended for bell peppers.
Pollen-Stigma Interactions following Compatible and Incompatible Pollinations in Hazelnut
Authors: Hampson Cheryl R. , Azarenko Anita Nina , Soeldner Al
Published: January 2019

Scanning electron microscopy was used to describe pollen-stigma interactions during compatible and incompatible pollinations of hazelnut (Corylus avellana L.), a species possessing sporophytic self-incompatibility. The stigmatic surface is of the dry type and was covered with elongated, rounded papillae. Compatible and incompatible pollen hydrated within 2 hours of pollination. Compatible pollen tubes emerged by 4 hours and grew into the style by 12 hours after pollination. Penetration of stigmatic papillae appeared to be intracellular in some cases. In incompatible pollinations, however, pollen tube emergence was delayed until at least 8 hours. The pollen tubes were distorted and did not penetrate the stigma.
Anatomical Changes in Rudbeckia hirta L. during Transition to Flowering
Authors: Harkess Richard L. , Lyons Robert E.
Published: January 2019

Histological and histochemical examination of floral initiation was conducted to determine the pattern of flowering in Rudbeckia hirta, a long-day (LD) plant. Plants were grown under 8-hour short days (SDs) until they had 14 to 16 expanded leaves. Half of the group of plants was moved to LD conditions consisting of natural daylength plus a 4-hour night interruption. Rudbeckia hirta had a pattern of differentiation in flowering similar to that reported in species requiring one inductive day for initiation. Rudbeckia hirta required 8 LDs for evocation and 18 LDs for completion of initiation. Involucral bracts initiated after 18 LDs, after which the receptacle enlarged and was capped by a meristematic mantle of cells signaling the start of development. Floret primordia did not initiate, even after 20 LDs. Increases in pyronin staining were observed in actively dividing cells of the procambium, leaf primordium, and corpus of the vegetative meristems. After 8 LDs, the pith rib meristem stained darkly, a result indicating the arrival of the floral stimulus. An increase in pyronin staining was also observed in the meristematic mantle covering the receptacle after 18 LDs, a result indicating increased RNA levels.
Genetic Control of Fruit Sugar Accumulation in a Lycopersicon esculentum × L. hirsutum Cross
Authors: Stommel John R. , Haynes Kathleen G.
Published: January 2019

Fruit of the cultivated tomato (Lycopersicon esculentum Mill.) store predominantly glucose and fructose whereas fruit of the wild species L. hirsutum Humb. & Bonpl. characteristically accumulate sucrose. Reducing sugar and sucrose concentrations were measured in mature fruit of parental, F1, F2, and backcross (BC1) populations derived from an initial cross of L. esculentum `Floradade' × L. hirsutum PI 390514. Generational means analysis demonstrated that additive effects were equal to dominance effects for percentage of reducing sugar. It was determined that a single major gene, dominant for a high percentage of reducing sugar, regulates the percentage of reducing sugar in tomatoes. We propose that this gene be designated sucr. Only additive effects were demonstrated to be important for glucose: fructose ratios. Using L. hirsutum as a donor parent for increasing total soluble solids concentration in the cultivated tomato is discussed.
Vesicular-arbuscular Mycorrhizal Peat-based Substrates Enhance Symbiosis Establishment and Growth of Three Micropropagated Species
Authors: Wang H. , Parent S. , Gosselin A. , Desjardins Y.
Published: January 2019

Micropropagated plantlets of Gerbera jamesonii H. Bolus ex Hook. F. `Terra Mix', Nephrolepis exaltata (L.) Schott `Florida Ruffles', and Syngonium podophyllum Schott `White Butterfly' were inoculated with two vesicular-arbuscular mycorrhizal (VAM) fungi, Glomus intraradices Schenck and Smith and G. vesiculiferum Gerderman and Trappe. They were potted in three peat-based media to determine the effects of mycorrhizal peat substrate on acclimatization and subsequent growth of micropropagated plantlets under greenhouse conditions. Symbiosis was established between the three ornamental species and VAM fungi within 4 to 8 weeks of culture in the greenhouse, but not during acclimatization. Mortality of Gerbera and Nephrolepis mycorrhizal plantlets was reduced at week 8 compared to the noninoculated control. A peat-based substrate low in P and with good aeration improved VAM fungi spread and efficiency. Mycorrhizal substrates had a long-term benefit of increasing leaf and root dry weight of Gerbera and Nephrolepis. Mycorrhizal Gerbera plants flowered significantly faster than non-mycorrhizal plants.
In Vitro and ex Vitro Adventitious Root Formation in Asian Jasmine (Trachelospermum asiaticum) I. Comparative Morphology
Authors: Apter R.C. , McWilliams E.L. , Davies F.T.
Published: January 2019

One-node explants and one-node stem cuttings of Asian jasmine [Trachelospermum asiaticum (Siebold & Zucc.) Nakai] were rooted, respectively, in vitro [tissue culture (TC)] or by conventional macropropagation (MACRO). The TC and MACRO stem bases were then analyzed for differences in the time-course sequence of 1) root primordia initiation and development and 2) adventitious root xylem development and root-to-shoot xylem connections. Early root primordia were observed at Day 3, and, by Day 7, root-to-shoot xylem connections were equally developed in TC and MACRO systems. Continued development and emergence of adventitious roots were observed at Days 8 to 10. At Days 13 and 18, when viewed using scanning electron microscopy, TC root hairs were morphologically thicker and one-third to one-half the length of MACRO root hairs. There was no apparent difference in root-hair density. Inferior TC root-hair length may be a factor in the acclimation of TC-generated plantlets.
Identifying Pollen Incompatibility Groups in California Almond Cultivars
Authors: Kester D.E. , Gradziel T.M. , Micke W.C.
Published: January 2019

Six cross-incompatibility groups, which contain most of commercially important California almond cultivars [Prunus dulcis (Mill.) D.A. Webb, syn. Prunus amygdalus Batch], and their self-incompatibility (S) allele genotypes are identified. Incompatibility groups include `Mission' (SaSb), `Nonpareil' (ScSd), and the four groups resulting from the `Mission' × `Nonpareil' cross: (SaSc), (SaSd), (SbSc), and (SbSd), as represented by `Thompson', `Carmel', `Merced' and `Monterey', respectively. All seedlings from the `Mission' × `Nonpareil' cross were compatible with both parents, a result indicating that these two cultivars have no alleles in common. Crossing studies support a full-sib relationship for these progeny groups and the origin of both parents from common germplasm. Cultivars in these six groups account for ≈ 93% of present California production, a result demonstrating a limited genetic base for this vegetatively propagated tree crop.