bluuebunny/crossref_metadata_2025 huggingface dataset:
Somatic Hybridization, an Integral Component of Citrus Cultivar Improvement: II. Rootstock Improvement
Authors: Grosser J.W. , Jiang J. , Louzada E.S. , Chandler J.L. , Gmitter F.G.
Published: February 2019

Production of tetraploid somatic hybrids that combine complementary diploid rootstock germplasm via protoplast fusion has become a practical strategy for citrus rootstock improvement, with the overall objective of packaging necessary disease and pest resistance into horticulturally desirable, widely adapted rootstocks. Citrus somatic hybridization techniques have been advanced to the point where numerous somatic hybrid rootstocks can now be produced and propagated for evaluation on a timely basis. Herein we report the production of 11 new somatic hybrid rootstock candidates from 12 different parents, including Milam lemon hybrid (Citrus jambhiri Lush.), Cleopatra mandarin (C. reticulata Blanco), sour orange (C. aurantium L.), `Succari' sweet orange [C. sinensis (L.) Osbeck], `Redblush' grapefruit (C. paradisi Macf.), `Nova' tangelo [C. reticulata × (C. paradisi × C. reticulata)], `Kinkoji' (C. obovoidea Hort. Ex Takahashi), Swingle citrumelo [C. paradisi × Poncirus trifoliata (L.) Raf.], Carrizo citrange (C. sinensis × P. trifoliata), rough lemon 8166 (C. jambhiri), and Palestine sweet lime (C. limettoides Tan.). All hybrids were confirmed by cytological and VNTR-PCR analyses, and have been propagated, budded with a commercial scion, and field-planted for performance evaluation.
Comparison of Controlled-release Nitrogen Fertilizers on Turfgrass in a Moderate Temperature Area
Authors: Zhang M. , Nyborg M. , Malhi S.S.
Published: February 2019

Coating of conventional urea with polymers is designed to improve N availability to crops. A field experiment was conducted from 1993 to 1994 on turfgrass at Ellerslie, Alta., Canada, to determine release rates of coated urea applied on turfgrass thatch surface, and the effect of coated urea application on growth, color, and N uptake of turfgrass. The experiment was established on existing stands of a mixture of `Merion' Kentucky bluegrass (Poa pratensis L.) and `Gennuina' creeping red fescue (Festuca rubra L.) growing on a Black Chernozemic (Typic Cryoboroll) soil. The annual rate of N application was 100 kg·ha-1 in 1993 and 1994. The release rate of urea fertilizers was determined by the weight loss of the fertilizer granules after application in polyvinyl chloride (PVC) cylinders inserted into the turfgrass thatch. Some coated urea fertilizers released most of their N within the growing season (e.g., Sherritt-G, Polyon 4%, and SulfurKote), while others released only half their N (e.g., Esso T-90 and Meister 7), probably because of the cool ambient summer temperature in the area. The growth and color of turfgrass were more uniform in some controlled-release fertilizer treatments (e.g., Esso T-90, Meister 7, Polyon 4%, and SulfurKote) than in noncoated urea and NH4NO3 treatments. Promotion of growth in 1994 as a residual effect of the 1993 controlled-release urea fertilizer application was also noted. The results suggest that the application of some controlled-release urea fertilizers (with 70- to 90-day release rates) can produce the most consistent quality turfgrass.
Gene Action and Heritability of High-temperature Fruit Set in Tomato Line CL5915
Authors: Hanson Peter M. , Chen Jen-tzu , Kuo George
Published: February 2019

High-temperature fruit set (heat tolerance) is a critical trait of tomato (Lycopersicon esculentum Mill.) cultivars targeted for lowland wet season production in the tropics and subtropics. Heat-tolerant Asian Vegetable Research and Development Center (AVRDC) tomato line CL5915-93D4-1-0-3 (CL5915) is a valuable source of heat-tolerance genes for tomato genetic improvement. The gene action of heat tolerance in CL5915 was determined by evaluating the F1, F2, BCP1, and BCP2 of a cross between CL5915 and heat-sensitive line UC204A for fruit set traits in two wet-season trials at AVRDC. Parent-offspring regression of F2-derived F3 (F2:3) family means on the F2 plants from CL5915 × UC204A was used to estimate the heritability of F2 single plant selection for heat tolerance. Mean percentage of fruit set and fruit number per cluster of the F1 and BCP1 exceeded midparent values and were not significantly different from those of CL5915, indicating complete dominance for heat tolerance. Generation means analyses indicated that a model including simple additive and dominance effects adequately explained the inheritance of mean fruit number per cluster both years. For mean percentage of fruit set, a model including simple additive-dominance effects produced an adequately fitting model in the 1996 season but the best-fitting model included an epistatic component in the 1997 season. Heritabilities estimated for fruit set traits in 1996 and 1997, respectively, were: 0.31 and 0.21 for percentage of fruit set; 0.28 and 0.14 for mean fruit number per cluster; and 0.53 and 0.15 for flower number per cluster. The low heritabilities for percentage of fruit set and mean fruit number per cluster under high temperatures imply that single plant selection in the F2 for heat tolerance from crosses involving CL5915 is not effective and that selection should be based on replicated family testing in the F3 and later generations.
Precooling, Planting Depth, and Shade Affect Cut Flower Quality and Perennialization of Field-grown Spring Bulbs
Authors: Cavins Todd J. , Dole John M.
Published: February 2019

Narcissus L. `Music Hall', N. `Tahiti', Tulipa L. `Couleur Cardinal', and T. `White Emperor' bulbs were precooled at 5 °C for 0 or 5 weeks and planted 15, 30, or 45 cm deep (from bulb base) into raised ground beds under 0%, 30%, or 60% shade. Plant growth was monitored for two consecutive years after planting. Precooling reduced the percentage of T. `White Emperor' that flowered but did not affect flowering percentage of the other cultivars. Precooling delayed anthesis in one or both years for all cultivars. The greatest percentage of bulbs flowered when planted 15 cm deep and the 45-cm planting depth reduced flowering percentage. Increasing planting depth delayed anthesis for all cultivars. Increasing shade increased stem lengths in one or both years for all cultivars, but did not influence flowering percentage. Perennialization was low for all cultivars regardless of treatment. Cultivar differences in perennialization occurred; in year 2 up to 30% of N. `Tahiti' bulbs flowered vs. 32% for `Music Hall' and up to 30% of T. `White Emperor' bulbs flowered vs. only 22% of `Couleur Cardinal'.
Growth, Development, and Yield of Head Lettuce Cultivated on Paper and Polyethylene Mulch
Authors: Brault D. , Stewart K.A. , Jenni S.
Published: February 2019

Lettuce plants (Lactuca sativa L. cv. Ithaca) were transplanted into organic soil and onto beige paper, black paper, and coextruded white/black polyethylene mulches in 1997 and 1998. A weeded bare ground plot was also tested. Transplanting in 1997 occurred in July under warm and dry conditions. Plants grown on mulch established better when the mean air temperature during the week after transplanting was 22.5 °C. The mortality rates of the bare ground control were 30%. All mulches significantly reduced plant mortality in 1997. In 1998, air temperature during the week after transplanting (June) was 14.6 °C. Plant mortality in 1998 was 1.3% for the control and 1.5% for the mulched plots. For both years, plants grown on mulched plots had higher relative growth rates than the control at the start of the season. Head fresh weight was 3.6 times (1997) and 1.2 times (1998) greater for lettuce grown on mulch compared with lettuce grown in a weeded control. Soil bulk density was lower under mulch than in the control plots in 1997.
An Assessment of the Effects of ENSO Events on Fresh Vegetable and Melon Supplies
Authors: Park Jaehong , Mjelde James W. , Fuller Stephen W. , Malaga Jaime E. , Rosson C. Parr , Dainello Frank J.
Published: February 2019

The historical effects of El Niño/La Niña events on supplies of selected fresh vegetables and melons (Cucumis melo L.) were evaluated by estimating single-equation supply relationships. Economic variables in the estimated equations were, generally, of the correct sign and significant at usual levels. El Niño events had a negative and statistically significant effect on the Texas muskmelon, Florida fall squash [Praecitrullus fistulosus Stocks) Pang.] and the California fall lettuce (Lactuca sativa L.) supply with expected production declines of 15%, 21%, and 5% relative to historical mean production. In contrast, the expected supplies of United States summer onions (Allium cepa L.) and Florida fall and winter tomatoes (Lycopersicon esculentum Mill.) increased about 7%, 10%, and 25% during El Niño events. La Niña events had a negative and significant effect on Texas muskmelon, honeydew, and watermelon, with supplies expected to decline 20%, 29%, and 13% with the occurrence of this event.
Divergent Transplant Production Practices Produce Comparable Growth, Yield, and Quality of Processing Tomatoes
Authors: Hartz T.K. , Giannini C. , Miyao E.M. , Valencia J.G.
Published: February 2019

The effect of transplant production and handling practices on processing tomato growth, yield, and fruit quality were evaluated in five field trials in California. In 1999, processing tomato (Lycopersicon esculentum Mill. cv. Halley) transplants were obtained from a number of commercial transplant producers and taken to the Univ. of California-Davis (UCD) where treatments were imposed for 1 week prior to transplanting. Treatments included N and P fertilization, exposure to lath house or greenhouse temperature, withholding water, and storage in the dark for 2 days to simulate shipment from greenhouse to field. Nine treatments per site were compared in field trials at Yolo, Woodland, and Knights Landing. In 2000, transplants were grown at UCD under varying nutrient regimes, including P fertilization rates ranging from weekly application of 0 to 90 mg·L-1. Two commercial field trials comparing 8 treatments were conducted near Winters and Newman. Although transplant production and handling practices significantly influenced relative growth rate in the 3-4 weeks following transplanting in all 1999 trials, effects on fruit yield were minimal, with only one treatment at Woodland showing significantly lower yield and no treatment differences in crop maturity, fruit soluble solids, or juice color observed at any site. In 2000, plants receiving no weekly P fertilization showed slower growth in the 3 weeks after transplanting, but no treatment differences were observed after 6 weeks. Fruit yield, soluble solids content (°Brix) and juice color were unaffected by transplant treatment. We conclude that transplant production and handling practices tested had minimal differential effect on the subsequent field performance of processing tomato transplants in the Central Valley of California.
Annual Life Cycle and Floral Development of 'Sarah Bernhardt' Peony in Israel
Authors: Barzilay Amalia , Zemah Hanita , Kamenetsky Rina , Ran Itzhak
Published: February 2019

The life cycle and morphogenesis of the floral shoot of Paeonia lactiflora Pallas cv. Sarah Bernhardt were studied under Israeli conditions. The renewal buds for the following year originate on the underground crown, at the base of the annual stems. Bud emergence begins in early spring. Stems elongate rapidly and reach heights of 50-70 cm in 60-70 days. Flowering begins in April and continues until the end of May. After flowering, the leafy stems remain green until September-October, when the leaves senesce, and the peony plant enters the “rest” stage for 3-4 months. The new monocarpic shoot initiated in the renewal bud at the end of June with the formation of the first leaf primordia and continued to increase in size until February. During summer, the renewal buds remain vegetative. The apical meristem ceases leaf formation after senescence of the aboveground shoots in the fall. During September, the apical meristem of the renewal buds reaches the generative stage and achieves the form of a dome, but remains undifferentiated. In October, floral parts become visible. Floral differentiation is terminated at the beginning of December. Floral initiation and differentiation of peony do not require low temperatures. Morphological development and florogenesis were similar to other geophyte species with an annual thermoperiodic life cycle.
Planting Date and Genotype Effects on Tepary Bean Productivity
Authors: Bhardwaj Harbans L. , Rangappa Muddappa , Hamama Anwar A.
Published: February 2019

Our objective was to evaluate production potential of eight tepary bean (Phaseolus acutifolius A. Gray) genotypes and three planting dates. Significant variation (P < 0.05) existed among eight genotypes and three planting dates in 1997 and 1998. The genotype ×planting date interaction was nonsignificant (P > 0.05) for seed yield and harvest index. Seed yields of eight genotypes, when averaged over three planting dates and 2 years, varied from 1618 to 1988 with a mean of 1816 kg·ha-1, indicating that tepary bean is adapted to Virginia's agro-climatic conditions. The harvest index (ratio between seed and total plant weight, expressed as percentage) ranged from 38% to 47%. Seed weight varied from 12.6 to 18.8 g with a mean of 14.5 g. Genotypes with tan-colored seeds had significantly larger seed than those with black or white seeds. Planting dates significantly affected seed yield, seed weight, and harvest index. The highest seed yield (2239 kg·ha-1) and harvest index were obtained from the late May plantings.
Root Epidermal Adhesion in Five Sweetpotato Cultivars during Curing and Storage
Authors: Blankenship Sylvia M. , Boyette Michael D.
Published: February 2019

`Beauregard', `Jewel', `Hernandez', `Carolina Rose', and `White Delight' sweetpotato [Ipomoea batatas (L.) Lam.] roots were placed in chambers for curing at 30 °C and 50%, 70%, or 85% relative humidity (RH) for 1 week. Uncured roots were held at 15 °C and 90% RH. After curing, roots were removed temporarily from the chambers, and chamber conditions were reset for the following storage treatments: 15 °C/85% RH; 18 °C/70% RH; and 18 °C/50% RH. Roots were stored 3 to 4 weeks. Experiments were in factorial arrangements so all combinations of curing and storage conditions were present. Experiments were conducted in two seasons. Roots were subjected to a pressurized water jet and the amount of skinning that occurred was visually rated several times during curing and storage. Weight loss was measured in `Beauregard'. Susceptibility to skinning changed over time and with the temperature and humidity conditions. Curing at 30 °C and any humidity between 50% and 85% generally improved epidermal adhesion, but there were exceptions. Lower humidities promoted greater weight loss. Epidermal adhesion changed during storage, becoming both stronger and weaker, indicating that sweetpotato epidermis is in an active state even after curing. The standard curing and storage conditions of 30 °C/85% RH and 15 °C/85% RH, respectively, are still a reasonable practice.
Trinexapac-ethyl Restricts Shoot Growth and Prolongs Stand Density of 'Meyer' Zoysiagrass Fairway Under Shade
Authors: Ervin E.H. , Ok C.H. , Fresenburg B.S. , Dunn J.H.
Published: February 2019

'Meyer' zoysiagrass (Zoysia japonica Steud.) is a popular turfgrass species for transition zone golf course fairways and tees because it is generally winter hardy while providing an excellent playing surface with minimal chemical and irrigation inputs. However, its functionality declines readily on many of the shaded areas on these courses. Reduced irradiance causes excessive shoot elongation, reduced tillering, and weak plants that are poorly suited to tolerate or recover from traffic and divoting. Trinexapac-ethyl (TE) effectively reduces gibberellic acid (GA) biosynthesis and subsequent shoot cell elongation. The objective of this study was to determine if monthly applications of TE would reduce shoot elongation of 'Meyer' zoysiagrass and improve stand persistence under two levels of shade. Shade structures were constructed in the field that continuously restricted 77% and 89% irradiance. A mature stand of 'Meyer' was treated with all combinations of three levels of shade (0%, 77%, and 89%) and three levels of monthly TE application [0, 48 g·ha-1 a.i. (0.5×), and 96 g·ha-1 a.i. (1×)] in 1998 and 1999. In full sun, the 0.5×-rate reduced clipping production by 17% to 20% over a four-week period and the 1×-rate by 30% to 37%. Monthly application of TE at the 1×-rate increased 'Meyer' tiller density in full sun and under 77% shade. Both rates of TE consistently reduced shoot growth under shade relative to the shaded control. Only the monthly applications at the 1×-rate consistently delayed loss of quality under 77% shade. The zoysiagrass persisted very poorly under 89% shade whether treated or not with TE and plots were mostly dead at the end of the experiment. Our results indicate TE can be an effective management practice to increase 'Meyer' zoysiagrass persistence in shaded environments. Chemical name used: 4-cyclopropyl-α-hydroxy-methylene-3,5-dioxocyclohexanecarboxylic acid ethyl ester (trinexapac-ethyl)
Inheritance of Resistance to Squash Mosaic Virus in a Squash Transformed with the Coat Protein Gene of Pathotype 1
Authors: Provvidenti R. , Tricoli David M.
Published: February 2019

In a yellow summer squash (Cucurbita pepo L.) experimental line developed by Seminis Vegetable Seeds, the coat protein gene of an American strain of squash mosaic virus (SqMV-M88), conferred resistance to Arizona, California, New Jersey, and New York strains belonging to the two pathotypes of the virus. An analysis of genetic populations derived from crosses and reciprocal backcrosses of a homozygous SqMV-resistant line A127-1-2 with the susceptible cultivar Butterbar revealed that the high level of resistance mimics the response of a single recessive gene.
Early Season Softwood Cuttings Effective for Vegetative Propagation of Juglans cinerea
Authors: Pijut Paula M. , Moore Melanie J.
Published: February 2019

Juglans cinerea L. (butternut) is a hardwood species valued for its wood and edible nuts. Information on the vegetative propagation of this species is currently unavailable. Our objective was to determine the conditions necessary for successful stem-cutting propagation of butternut. In 1999 and 2000, 10 trees (each year) were randomly selected from a 5- and 6-year-old butternut plantation located in Rosemount, Minn. Hardwood stem cuttings were collected in March, April, and May. Softwood cuttings were collected in June and July. K-IBA at 0, 29, or 62 mm in water and IBA at 0, 34, or 74 mm in 70% ethanol were tested for root induction on cuttings. The basal end of cuttings were dipped in a treatment solution for 10 to 15 seconds, potted in a peat: perlite mixture, and placed in a mist bed for 5 to 8 weeks. Rooted cuttings were gradually hardened off from the mist bed, allowed to initiate new growth, over-wintered in a controlled cold-storage environment, and then outplanted to the field. For hardwood cuttings, rooting was greatest for those taken in mid-May (branches flushed out), 22% with 62 mm K-IBA and 28% with 74 mm IBA. Softwood cuttings rooted best when taken in June (current season's first flush of new growth or softwood growth 40 cm or greater) and treated with 62 mm K-IBA (77%) or 74 mm IBA (88%). For 1999, 31 out of 51 rooted softwood cuttings (60.8%) survived overwintering in cold storage and acclimatization to the field. For 2000, 173 out of 186 rooted softwood cuttings (93%) survived overwintering and acclimatization to the field. Chemical names used: indole-3-butyric acid-potassium salt (K-IBA); indole-3-butyric acid (IBA).
Effect of Planting Date on Vegetable Amaranth Leaf Yield, Plant Height, and Gas Exchange
Authors: Whitehead W.F. , Carter J. , Singh B.P.
Published: February 2019

Field studies were conducted during 1992 and 1993 to determine the effect of six monthly planting dates from April to September on gas exchange, plant height, and leafy fresh and dry yields of vegetable amaranth (Amaranthus tricolor L.). Vegetative growth was satisfactory for May to August planting. Seeds planted in April failed to germinate due to low soil temperatures. Plant growth was significantly reduced in the September planting possibly due to low fall temperatures and shortened day length. Soil and air temperatures 25 °C or higher promoted optimal stand establishment and growth. The vegetative growth of June seeded amaranth took place during the warmest part of the summer and as a result had maximum CO2 exchange rate (CER), plant height, and leafy fresh and dry yields. The relationship between planting date and CER, transpiration rate (E), stomatal conductance (gs), plant height, and leafy fresh and dry yields was quadratic, while a cubic equation provided best fit between the planting date and internal leaf CO2 concentration (Ci). The results suggest that it is possible to stagger the planting of Amaranthus tricolor in the southeastern United States to assure availability of fresh leafy greens throughout the summer. However, the crop produces maximum leaf biomass when grown during the warmest part of the summer.
Photoperiod Improves Long-term Survival of In Vitro-stored Strawberry Plantlets
Authors: Reed Barbara M.
Published: February 2019

Cold storage is important for managing in vitro germplasm collections. Strawberry shoot cultures can typically be held at 4 °C for 9 to 24 months before they require repropagation. Concentration of BA in the storage medium, pre-storage cold acclimatization (CA), and exposure to a photoperiod during storage were studied to determine conditions for improved strawberry culture storage. Fragaria shoot cultures stored at 4 °C were rated for plantlet condition on a 0-5 scale at 9, 12, and 19 months. Four species were CA and stored on medium with 0, 1, 2.5, or 5 μm BA either in darkness or under a 12-hour photoperiod. Mean ratings over all treatments and genotypes were best at 9 and 12 months (3.4) and declined at 19 months (2.2). BA in the storage medium significantly improved ratings for two species at 9 and 12 months, but ratings were not significantly different at 19 months. At 19 months of storage, shoot cultures stored with a photoperiod were rated significantly better (P ≤ 0.05) than those grown in darkness. Five Fragaria genotypes stored on medium without BA were used to study the effect of photoperiod and CA on ratings of stored plantlets. CA-shoot cultures stored for 9 or 12 months were rated significantly better than non-CA cultures. After 12 and 19 months storage, three of the five genotypes stored under a 12-hour photoperiod had significantly higher ratings than those stored in the dark (P ≤ 0.01), but by 19 months CA was nonsignificant. Overall, the addition of a photoperiod improved the condition of Fragaria shoot cultures stored at 4 °C. Chemical name used: N6-benzyladenine (BA).
A Monocot Plant Identified as an Alternate Host of the Causal Agent of Bacterial Spot of Tomato and Pepper
Authors: Gibbs Harold A.A.
Published: February 2019

Xanthomonas campestris pv. vesicatoria (Xcv) recovered from Commelina benghalensis L., caused bacterial spot disease in cultivars of pepper and tomato susceptible to the pathogen. This is the first reported case of a dicot-infecting Xc pathovar infecting a monocot plant, represented here by a member of the Family Commelinaceae. Laboratory strains of the pathogen that included 81-23, 81-23M13, 82:4, 2595, and P6AD4, known to be pathogenic to pepper and tomato, promoted bacterial spot symptoms on leaves of C. benghalensis L. Of the 63 field isolates recovered from infected C. benghalensis L., 30 gave biochemical and physiological reactions consistent with Xcv pathogens, whereas 10 of the latter promoted bacterial spot disease in the test cultivars resulting in the identification of seven pathogenic races, including P2, P5, P6, P5T1, P5T2, P6T2, and P6T3. Bacterial spot disease symptoms developed on stems only when C. benghalensis L. was spray-inoculated with strains 81-23, 81-23M13, and P6AD4. Bacterial concentration increased in planta by as much as 103 per lesion of the leaf, whereas growth of the same strains was restricted in the stem of this weed. Growth of these three strains was, however, significantly (P ≤ 0.05) lower on NYGA amended with C. benghalensis L. stem extract than on NYGA amended with leaf extract. The ability of the bacterial spot pathogen to infect the stem of C. benghalensis L. has serious implications for management of bacterial spot disease in fields populated with this weed since stems of this plant infected with the pathogen continue to grow vegetatively and disperse throughout all fields in which it is found.
A Cultivar by Any Other Name: Genetic Variability in Heirloom Bell Pepper 'California Wonder'
Authors: Votava Eric J. , Bosland Paul W.
Published: February 2019

Random amplified polymorphic DNA (RAPD) analysis can provide a means of evaluating and comparing genetic variability within cultivars. The purpose of this study was to evaluate the relative genetic variability between accessions of two open-pollinated bell pepper cultivars: 'California Wonder', an heirloom cultivar, and 'Jupiter', a modern cultivar. RAPD molecular markers were used to assess the genetic variability between accessions of these two cultivars. The high levels of genetic variability found among accessions of 'California Wonder' may preclude its use as a standard cultivar in research.
Host Reactions of Sweetpotato Genotypes to Root-knot Nematodes and Variation in Virulence of Meloidogyne incognita Populations
Authors: Cervantes-Flores J.C. , Yencho G.C. , Davis E.L.
Published: February 2019

Sweetpotato [Ipomoea batatas (L.) Lam.] genotypes were evaluated for resistance to North Carolina root-knot nematode populations: Meloidogyne arenaria (Neal) Chitwood races 1 and 2; M. incognita (Kofoid & White) Chitwood races 1, 2, 3, and 4; and M. javanica (Treub) Chitwood. Resistance screening was conducted using 150-cm3 Conetainers containing 3 sand: 1 soil mix. Nematode infection and reproduction were assessed as the number of egg masses produced by root-knot nematodes per root system. Host suitability for the root-knot nematode populations differed among the 27 sweetpotato genotypes studied. Five genotypes (`Beauregard', L86-33, PDM P6, `Porto Rico', and `Pelican Processor') were selected for further study based on their differential reaction to the different root-knot nematodes tested. Two African landraces (`Tanzania' and `Wagabolige') were also selected because they were resistant to all the nematode species tested. The host status was tested against the four original M. incognita races, and an additional eight populations belonging to four host races, but collected from different geographical regions. The virulence of root-knot nematode populations of the same host race varied among and within sweetpotato genotypes. `Beauregard', L86-33, and PDM P6 were hosts for all 12 M. incognita populations, but differences in the aggressiveness of the isolates were observed. `Porto Rico' and `Pelican Processor' had different reactions to the M. incognita populations, regardless of the host race. Several clones showed resistance to all M. incognita populations tested. These responses suggest that different genes could be involved in the resistance of sweetpotato to root-knot nematodes. The results also suggest that testing Meloidogyne populations against several different sweetpotato hosts may be useful in determining the pathotypes affecting sweetpotato.
Medium-incorporated PEG-8000 Reduces Elongation, Growth, and Whole-canopy Carbon Dioxide Exchange of Marigold
Authors: Burnett Stephanie E. , van Iersel Marc W. , Thomas Paul A.
Published: February 2019

French marigold (Tagetes patula L. `Boy Orange') was grown in a peat-based growing medium containing different rates (0, 15, 20, 30, 42, or 50 g·L–1) of polyethylene glycol 8000 (PEG-8000) to determine if PEG-8000 would reduce seedling height. Only 28% to 55% of seedlings treated with 62, 72, or 83 g·L–1 of PEG-8000 survived, and these treatments would be commercially unacceptable. Marigolds treated with the remaining concentrations of PEG-8000 had shorter hypocotyls, and were up to 38% shorter than nontreated controls at harvest. Marigold cotyledon water (ψw), osmotic (ψs), and turgor (ψp) potentials were significantly reduced by PEG-8000, and ψp was close to zero for all PEG-treated seedlings 18 days after seeding. Whole-plant net photosynthesis, whole-plant dark respiration, and net photosynthesis/leaf area ratios were reduced by PEG-8000, while specific respiration of seedlings treated with PEG-8000 increased. Marigolds treated with concentrations greater than 30 g·L–1 of PEG-8000 had net photosynthesis rates that were close to zero. Fourteen days after transplanting, PEG-treated marigolds were still shorter than nontreated seedlings and they flowered up to 5 days later. Concentrations of PEG from 15 to 30 g·L–1 reduced elongation of marigold seedlings without negatively affecting germination, survival, or plant quality. It appears that marigold seedlings were shorter because of reduced leaf ψp and reductions in net photosynthesis.
Predispositional Effect of Soil Water Saturation on Infection of Chile Pepper by Phytophthora capsici
Authors: Sanogo S.
Published: February 2019

Phytophthora capsici is a serious soilborne pathogen in chile pepper [Capsicum annuum L.] in New Mexico, and has been shown to spread under high soil moisture conditions and cause losses in a wide array of crops worldwide. This study was conducted to assess whether soil water saturation predisposes chile pepper to infection by P. capsici. Potted chile pepper plants of `Criollo de Morelos 334' (`CM334') and `New Mexico 6-4' (`NM6-4'), resistant and susceptible to P. capsici, respectively, were subjected to soil water saturation conditions (saturated and nonsaturated) for 3 and 6 days at two growth stages (six- to eight-leaf stage and one- to four-flower bud stage) prior to being inoculated or noninoculated with zoospores of P. capsici. Regardless of growth stage, no disease symptoms developed in `CM334' grown either under saturated or nonsaturated soil conditions at any of the two periods (3 or 6 days) of soil water saturation. In `NM6-4', disease symptoms consisting of stem necrosis, defoliation, and wilting were expressed. Plant growth stage at inoculation had a significant effect on disease severity (P < 0.0001). However, the response of `NM6-4' to P. capsici at each growth stage under saturated soil conditions was similar to that under nonsaturated conditions regardless of the period of saturation (P = 0.09). These results indicate that soil water saturation does not exert a significant predispositional effect on infection of chile pepper by P. capsici.
Olive Oil Quality Decreases with Nitrogen Over-fertilization
Authors: Fernández-Escobar R. , Beltrán G. , Sánchez-Zamora M.A. , García-Novelo J. , Aguilera M.P. , Uceda M.
Published: February 2019

Mature `Picual' olive (Olea europaea L.) trees growing in two different localities of Córdoba and Jaén provinces, southern Spain, were subjected to annual applications of 0, 0.12, 0.25, 0.50, or 1.0 kg N/tree in the Cordoba's experiment, and to 0 or 1.5 kg N/tree in the Jaén's experiment. Nitrogen was applied 50% to the soil and 50% through foliar application in Córdoba, and 100% to the soil in Jaén. Three years after the initiation of treatments, when the trees showed differences among them in nitrogen content, fruit were sampled at maturity from each experimental tree during six consecutive seasons to determine the effect of nitrogen fertilization on olive oil quality. Tree nitrogen status was always above the threshold limit for deficiency even in control trees, indicating that most treatments caused nitrogen over fertilization. Nitrogen in excess was accumulated in fruit and, consequently, polyphenol content, the main natural antioxidants, significantly decreased in olive oil as nitrogen increased in fruit. The decrease in polyphenols induced a significant decrease in the oxidative stability of the oil and its bitterness. Tocopherol content, on the contrary, increased with nitrogen application, mainly by an increase in α-tocopherol, the main component in the olive oil. No effect was found on pigment content, particularly carotenoid and chlorophyllic pigments, neither on fatty acid composition.
Foliar- and Fruit-applied Strontium as a Tracer for Calcium Transport in Apple Trees
Authors: Rosen Carl J. , Bierman Peter M. , Telias Adriana , Hoover Emily E.
Published: February 2019

Application of calcium (Ca) sprays is a recommended practice to reduce the incidence of Ca-related disorders such as bitter pit in apple (Malus ×domestica), but effectiveness of sprays to increase Ca concentrations in the fruit is not always consistent. Strontium (Sr) has been used as a Ca analog to evaluate Ca transport processes and distribution in plants. A field study was conducted using foliar- and fruit-applied Sr as a tracer for Ca transport in 20-year-old `Honeycrisp' apple trees on Malling.26 (M.26) rootstock. The objectives of this study were to 1) measure the amount of Sr translocation from leaves to fruit, 2) determine the effectiveness of eight sprays applied over the growing season vs. four late-season sprays on increasing Sr concentrations in leaves and fruit, and 3) evaluate the effect of an experimental adjuvant consisting of alkyl-polysaccharides and monosaccharides on spray efficacy. Seven treatments were tested, which included a control and six Sr treatments applied in various combinations with or without an adjuvant. Trees were sprayed four or eight times during the growing season, either directly to leaves and fruit or to leaves only (fruit covered during application). Spray treatments did not significantly affect total fruit fresh or dry weight. Although some discrimination between Ca and Sr was detected, the similar distribution of Ca and Sr in fruit tissue of control treatments suggested that Sr is a suitable tracer for Ca. Based on the covered vs. uncovered fruit treatments, about 11% to 17% of the Sr in the fruit came from Sr applied directly to the leaves. Eight spray applications over the growing season more than doubled both the concentration and content of fruit Sr compared with four late season sprays. The tested adjuvant doubled Sr absorption by and translocation to fruit compared with not using an adjuvant. Assuming similar transport for Ca and Sr, and adjusting for the atomic weight of Ca relative to Sr, the maximum increase in fruit Ca concentration at harvest from foliar and fruit applications (eight sprays with adjuvant and uncovered fruit) would have been as follows: core = 78 mg·kg–1; flesh = 35 mg·kg–1; peel = 195 mg·kg–1; entire fruit = 67 mg·kg–1. In addition to being an underused tool for studying Ca transport patterns, the results also suggest that use of Sr may be a novel technique for testing the efficacy of various adjuvants used to enhance uptake and transport of Ca in leaves and fruit.
Iron Form and Concentration Affect Nutrition of Container-grown Pelargonium and Calibrachoa
Authors: Wik Ron M. , Fisher Paul. R. , Kopsell Dean A. , Argo William R.
Published: February 2019

Two experiments were completed to determine whether the form and concentration of iron (Fe) affected Fe toxicity in the Fe-efficient species Pelargonium ×hortorum `Ringo Deep Scarlet' L.H. Bail. grown at a horticulturally low substrate pH of 4.1 to 4.9 or Fe deficiency in the Fe-inefficient species Calibrachoa ×hybrida `Trailing White' Cerv. grown at a horticulturally high substrate pH of 6.3 to 6.9. Ferric ethylenediaminedi(o-hydroxyphenylacetic) acid (Fe-EDDHA), ferric ethylenediamine tetraacetic acid (Fe-EDTA), and ferrous sulfate heptahydrate (FeSO4·7H2O) were applied at 0.0, 0.5, 1.0, 2.0, or 4.0 mg ·L–1 Fe in the nutrient solution. Pelargonium showed micronutrient toxicity symptoms with all treatments, including the zero Fe control. Contaminant sources of Fe and Mn were found in the peat/perlite medium, fungicide, and lime, which probably contributed to widespread toxicity in Pelargonium. Calibrachoa receiving 0 mg Fe/L exhibited severe Fe deficiency symptoms. Calibrachoa grown with Fe-EDDHA resulted in vigorous growth and dark green foliage, with no difference from 1 to 4 mg·L–1 Fe. Using Fe-EDTA, 4 mg Fe/L was required for acceptable growth of Calibrachoa, and all plants grown with FeSO4 were stunted and chlorotic. Use of Fe-EDDHA in water-soluble fertilizer may increase the upper acceptable limit for media pH in Fe-inefficient species. However, iron and Mn present as contaminants in peat, irrigation water, or other sources can be highly soluble at low pH. Therefore, it is important to maintain a pH above 6 for Fe-efficient species regardless of applied Fe form or concentration, in order to avoid the potential for micronutrient toxicity.
Molecular Characterization of Three Comercial Cultivars and a New Pollinator in Kiwifruit
Authors: Prado M.J. , Romo S. , Novo M. , Rey M. , Herrera M.T. , González M.V.
Published: February 2019

We investigated the characterization of genotypes of Actinidia deliciosa (Chev.) Liang and Ferguson var. deliciosa by using isozymatic and molecular techniques [randomly amplified polymorphic DNA (RAPD), amplified fragment-length polymorphism (AFLP), standard AFLP, and modified AFLP]. Four genotypes were tested, the female cultivar `Hayward', the traditional New Zealand pollinizers `Matua' and `Tomuri', and a new pollinizer named clone A selected in a breeding program in Spain. PGI and PGM were the only isozymes that allowed us to distinguish the kiwifruit genotypes, although the accessions of `Matua' presented two different banding patterns for both isozymes. All three molecular markers differentiated between the genotypes of kiwifruit tested, although RAPD markers did not allow us to establish differences between accessions of `Matua', while both standard and modified AFLP did. These results, along with those of isozymes, support the hypothesis that the male kiwifruit genotypes present in Europe belong to different clones. None of the markers used showed differences between accessions of `Hayward', which would suggest that it is a uniform cultivar. On the other hand, clone A was a seedling derived from `Hayward' and an unknown pollinizer. The results obtained using AFLP markers strongly suggest that `Tomuri' may have been the male parent of clone A. A specific protocol for kiwifruit characterization based on a modified AFLP technique is also presented, that gave rise to the highest percentage of polymorphism while scoring the lowest number of bands. This, together with the technical features of modified AFLP markers, make them very useful for identifying propagated kiwifruit plant material in commercial nurseries.
Methods to Ensure Microbiological Safety of Organically Produced Medicinal Plants: A Review
Authors: Rushing James W.
Published: February 2019

The production, handling, processing and marketing of over-the-counter medicinal products manufactured from plants is virtually unregulated. This can include dietary supplements, functional foods and nutraceuticals, any of which may contain botanical constituents. Of particular concern is the possible presence of human pathogens in products offered at retail. A review of literature is presented. Options for sterilizing herbal medicinal products, including fumigation, irradiation and heat treatments, are presented. Experiences of the spice industry are discussed as they relate to the development of similar protocols for herbal medicines. Methods used to ensure microbiological safety must be evaluated for their effect on the medicinally active constituents in the plant material. Very little data of this nature are available. Avenues for future research are proposed.
European and Asian Pears: Simple Sequence Repeat–Polyacrylamide Gel Electrophoresis-based Analysis of Commercially Important North American Cultivars
Authors: Ghosh Ashok K. , Lukens Lewis N. , Hunter David M. , Strommer Judith N.
Published: February 2019

The genus Pyrus (pear) includes species and cultivars of great diversity. We have tested the feasibility of a polyacrylamide gel eletrophoresis (PAGE)-based +/– simple sequence repeat (SSR) screen as a means of defining relationships amongst pears of commercial importance in North America. The screen included 28 pear accessions, including economically important cultivars, numbered selections from breeding programs and interspecific hybrids. It relied on 18 SSR primer pairs, each of which produced polymorphic banding patterns in all the genotypes examined. Fragments were scored for presence or absence within genotypes. The results show that amplification and analysis of a small number of SSR loci enable identification of cultivars and reasonable definition of genetic relationships in North American pears. Seven primer pairs were sufficient to distinguish the 28 pear cultivars. Analyses using both distance and parsimony criteria grouped cultivars in a manner consistent with known pedigrees and sites of origin.
Resistance to Infection by Fungal, Bacterial, and Viral Pathogens in a Common Bean Core Collection from the Iberian Peninsula
Authors: Monteagudo Ana B. , Rodiño A. Paula , Lema Margarita , De la Fuente María , Santalla Marta , De Ron Antonio M. , Singh Shree P.
Published: February 2019

Availability of germplasm with high level of resistance is essential for broadening the genetic base and breeding crop cultivars resistant to abiotic and biotic stresses. The objective of this study was to determine reaction of a common bean core collection from the Iberian Peninsula to anthracnose, rust, common and halo blights, bean common mosaic virus (BCMV, a potyvirus) and bean common mosaic necrosis virus (BCMNV, a potyvirus) pathogens. Of 43 accessions evaluated, 14 large-seeded Andean type, seven small-seeded Middle American type and seven with intermediate characteristics or recombinant type between the two gene pools had resistant reaction to one or more diseases. Resistance to race 17 or 23 of anthracnose pathogen was present in 17 accessions and four accessions were resistant to both races. Resistance to race 38 or 53 of rust pathogen was shown by 22 accessions and five accessions were resistant to both races. All accessions were susceptible to common bacterial blight and 12 accessions had resistance to halo blight. Ten accessions showed resistance to BCMV, none to BCMNV, and two were variable to both viruses. Accessions such as PHA-0573 (pinto), PHA-0589 (marrow), PHA-0654 (favada pinto), and PHA-0706 (favada) showed resistance to two or more diseases. These accessions may be valuable in breeding Andean bean for enhancing simultaneous utilization of both large seed size and disease resistance.
Effect of Aminoethoxyvinylglycine and Surfactants on Preharvest Drop, Maturity, and Fruit Quality of Two Processing Peach Cultivars
Authors: Cline J.A.
Published: February 2019

The effect of aminoethoxyvinylglycine (AVG), commercially available as ReTain, and three organo-silicone surfactants were evaluated in a series of four experiments over a 2-year period in two commercial peach orchards. Four rates of AVG (0, 66, 132, and 264 mg·L–1 AVG; all applied with 0.05% Sylgard 309) and three surfactants (0.05% Sylgard 309; 0.05% Regulaid; and 0.50% LI-700; all applied with 132 mg·L–1 AVG) were applied to `Venture' and `Babygold 7' peach trees 10 days before first harvest. Fruit were harvested according to commercial standard maturation criteria of background color, suture filling, and fruit size. Treatments were assessed in relation to fruit maturity, delay in harvest, fruit size and yield, fruit quality (flesh firmness and brix), as well as fruit quality following 2 weeks of cold storage. Based on sequential harvest data, the maturation of the AVG treated trees was delayed by about 3 to 4 days. Fruit from AVG treated trees were firmer at harvest and 2 weeks following cold storage at 2°C. However, no additional increase in fruit size or yield was detected. In addition, the addition of a surfactant was not necessary for AVG to be efficacious for delaying maturity and enhancing firmness when applied at 132 mg·L–1 AVG. However, when the three surfactants were compared, Regulaid and Li 700 advanced color development in one experiment and Li-700 resulted in firmer fruit in another. Aminoethoxyvinylglycine applications to the clingstone cultivars `Venture' and `Babygold 7' can be used successfully to manage harvest activities by delaying the onset of picking and improving fruit firmness.
High Soil Moisture and Low Soil Temperature Are Associated with Chlorosis Occurrence in Concord Grape
Authors: Davenport Joan R. , Stevens Robert G.
Published: February 2019

Leaf yellowing (chlorosis) is not unique to Concord grape, yet occurs with great intensity in the arid, irrigated central Washington state growing region. Past research on nutrients has not shown a clear cause and effect relationship between soil and/or plant nutrient status and chlorosis. We investigated both nutritional and climatic conditions for their association with chlorosis occurrence. Six vineyard sites were selected, 2 each with no history of chlorosis (achlorotic), occasional chlorosis, and annually reoccuring chlorosis (chronically chlorotic) and monitoring sites in chlorotic and achlorotic areas were established. Nutrient elements K, Ca, Mg, Mn, and Cu plus the nonnutrient elements Na and Al were monitored in soil (surface, 0 to 30 cm, and subsurface, 30 to 75 cm, depths) and leaf tissue (both petioles and blades) prebud burst (soil only), at bloom, and preveraison at 650 degree days at all vineyard sites for the 2001, 2002, 2003, and 2004 growing seasons. In addition, both soil temperature and moisture were monitored. To evaluate the intensity of chlorosis at each site, chlorotic vines were GPS marked and mapped post-bloom each year. Overall, chlorosis incidence was more widespread in 2001 and 2003 than in 2002 or 2004. There were few relationships with soil or tissue nutrient concentrations. However, soil moisture was consistently higher and soil temperature lower in the period between bud burst and bloom in the chlorotic sites. This suggests that a cold, wet soil environment prior to bloom impedes grape root growth and/or function and triggers plant chlorosis. Yearly differences strongly support this finding.
Comparative Effects of NaCl and CaCl2 Salinity on Cucumber Grown in a Closed Hydroponic System
Authors: Trajkova Fidanka , Papadantonakis Nicolas , Savvas Dimitrios
Published: February 2019

The objective of this study was to discriminate among Na, Cl, and Ca salinity effects on cucumber (Cucumis sativus L.). Cucumber plants grown in perlite were exposed for 134 days to low and moderate levels of salinity induced by the addition of either NaCl or CaCl2 at equal rates (on a chemical equivalent basis) to a standard nutrient solution for cucumber up to two target electrical conductivity (EC) levels (3.0 and 5.0 dS·m–1). The experimental treatments included also a control, which was irrigated with the standard nutrient solution without additional salt. The mean EC values in the drainage solution were 2.35, 3.94, 4.2, 6.31, and 6.35 dS·m–1 for the control, low NaCl, low CaCl2, high NaCl, and high CaCl2 treatments, respectively. The fresh and dry weights of stems and leaves were reduced only under conditions of high NaCl salinity, whereas root mass was not affected. Fruit yield decreased in proportion to the increase in NaCl salinity, while CaCl2 salinity reduced yield only at the high EC, to a level that corresponded to the low NaCl salinity. The suppression of yield with increasing salinity resulted mainly from a decrease in fruit size, while the number of fruit per plant was reduced to a lesser extent. These changes caused a reduction in the number of Class I fruit and an increase in nonmarketable produce. Both salinity sources enhanced the total soluble solids and the fruit chlorophyll concentration. NaCl salinity appreciably raised the concentrations of Na and Cl in young and old leaves, and suppressed the K concentration. CaCl2 salinity increased leaf Cl and Ca levels and diminished Mg and K. It is concluded that cucumber is more susceptible to NaCl salinity than to equal EC levels of CaCl2 salinity.