bluuebunny/crossref_metadata_2025 huggingface dataset:
Storability in Cold Temperatures Can Be Evaluated Based on Changes in Fruit Quality in Apple Genotypes Under Shelf Life Conditions
Authors: Iwanami Hiroshi , Moriya Shigeki , Kotoda Nobuhiro , Takahashi Sae , Abe Kazuyuki
Published: February 2019

To compare changes in fruit quality during cold storage with those during shelf life conditions, flesh firmness and titratable acidity (TA) were measured during storage in 20 apple (Malus ×domestica Borkh.) cultivars. Fruit of each cultivar were divided into two groups and stored in chambers controlled at 20 ± 2 °C and 85 ± 5% relative humidity (RH) (shelf life conditions) or 0.5 ± 0.3 °C and 95 ± 5% RH (cold storage). Five of the stored fruit were removed for measurements at 5- or 10-d intervals for 40 d and at 1-month intervals until 10 months after harvest at 20 °C and 0.5 °C, respectively. Data for firmness and TA were subjected to a linear regression and a nonlinear regression, respectively. Moreover, to determine the advantages of 0.5 °C storage over 20 °C storage for retaining firmness and TA, the effect of storage type on extending the storage period was introduced as a parameter. The estimate of the effect of storage type showed that firmness and TA could be retained 8.9 and 3.7 times, respectively, longer at 0.5 °C than 20 °C, independently of the cultivar. Therefore, firmness and TA after cold storage could be predicted by the change in firmness and TA during shelf life conditions. Moreover, cultivar differences regarding quality change under cold storage could be determined in a short period after harvest because the cultivar differences under shelf life conditions were detected within 1 month after harvest.
Genetic Diversity of Hazelnut (Corylus avellana L.) Germplasm in Northeastern Spain
Authors: Boccacci Paolo , Botta Roberto , Rovira Mercè
Published: February 2019

In Spain, hazelnut is mainly cultivated in Catalonia, a region in the northeast. The province of Tarragona accounts for 88% of the total Spanish area planted to hazelnut. Almost 80% of the production in Tarragona is of the local cultivar Negret, with others cultivated to a lesser extent. Minor cultivars are only sporadically present in older orchards, farm yards and gardens, and have been collected for preservation. In this work, 16 SSR markers were used to fingerprint 18 minor hazelnut cultivars from northeastern Spain. Their microsatellite profiles were combined with those of 15 Spanish cultivars characterized in a previous work, and used to study the genetic diversity in 33 genotypes including local Spanish germplasm. The SSR analysis allowed development of unique profiles of each of the 18 cultivars, and no new case of synonymy was detected. A high level of genetic diversity (mean He = 0.7) was observed in 33 genotypes, although a high number of them showed a close genetic relationship. The dendrogram generated by UPGMA cluster analysis placed the 33 accessions into nine main groups, related to their putative pedigrees or geographical area of cultivation. All investigated Negret-type cultivars were found to be distinct from Negret, and only a few cultivars within this germplasm appeared to be seedlings of Negret. The results will be useful in the conservation of hazelnut germplasm and in the selection of parents for use in breeding.
Fruit Shape Analysis of Vitis Using Digital Photography
Authors: Wycislo Andrew P. , Clark John R. , Karcher Douglas E.
Published: February 2019

Quantifying fruit shape is challenging, particularly when measurements are made on segregating populations of plants. Objective manual measurements can be performed on small samples of fruit, but this method is difficult and very time-consuming when dealing with larger samples or when shapes are complex or shape variations are slight. Subjective rating scales can also be used, but their effectiveness is questionable when done by multiple raters resulting from varying descriptive standards among individuals. Therefore, a method was developed to analyze digital images containing multiple fruits to characterize fruit shapes. Each segregant of a population of table grapes (Vitis spp.) with parents of wide shape variation was photographed and analyzed for shape using SigmaScan® software. The program discriminately selected image pixels representing the fruit and determined the area and perimeter of a grape berry, which were subsequently used to calculate the major:minor axis ratio, shape factor, and compactness values. Computer findings were compared with data from human raters using a simple correlation. When compared with the human ratings, results showed strong correlations of r = 0.941 for major:minor axis ratio, r = –0.804 for shape factor, and r = 0.744 for compactness. This analysis method was a reasonably quick and simple way to quantify grape berry shape, yielding valuable phenotypic data in numerical form. This technology should be useful for shape characterizations in other fruits as well.
Root Pruning Effects on Growth and Yield of Red Raspberry
Authors: Darnell Rebecca L. , Alvarado-Raya Horacio E. , Williamson Jeffrey G.
Published: February 2019

Annual production systems for red raspberry (Rubus idaeus L.) have been proposed for off-season production or for increasing crop diversity in warm winter climates. However, yields in these annual systems are low compared with annual yields in perennial production systems. The yield reduction may be from the root pruning that occurs during removal and shipment of the canes from the nursery. This would result in significant root loss and may decrease the availability of root carbohydrates for reproductive development. To investigate this, ‘Cascade Delight’ red raspberry plants were root pruned during dormancy, and growth and fruiting of these plants were compared with non root-pruned controls the next season. Dry weights of all organs except floricane stems increased throughout the growing season; however, root pruning decreased root, floricane lateral, and total fruit dry weight compared with no root pruning. The yield decrease observed in root-pruned plants was because of a decrease in flower and fruit number per cane compared with the control. Total carbohydrate concentration in roots of root-pruned and non root-pruned plants decreased significantly between pruning and budbreak; however, root carbohydrate concentration and content were always lower in root-pruned compared with non root-pruned plants. The lower root carbohydrate availability in root-pruned compared with non root-pruned plants during budbreak apparently limited flower bud formation/differentiation, resulting in decreased yield. These results suggest that yields in annual red raspberry production systems are limited because of the loss of root carbohydrates during removal from the nursery. Management practices that increase yield per plant (e.g., by ameliorating root loss) or increase yields per hectare (e.g., by increasing planting density) are needed to render the annual production system economically viable.
A Novel Mechanism for Xenia?
Authors: Liu Yongsheng
Published: February 2019

Although xenia is widespread in plants and has applications in genetics, physiology, breeding and production, its mechanism remains poorly understood. Here I briefly discuss several previous explanations for xenia, and propose an mRNA action hypothesis, which is consistent with Darwin's Pangenesis.
Improving the Productivity, Quality, and Storability of ‘Katja’ Apple by Better Orchard Management Procedures
Authors: Tahir Ibrahim I. , Johansson Eva , Olsson Marie E.
Published: February 2019

This 4-year study at the Kivik research station, southeastern Sweden (≈55°N), investigated optimal orchard management procedures to improve tree growth, yield, fruit quality, and storability in the important early season apple cultivar ‘Katja’. Two procedures (one standard, one novel) were applied within pruning, weed control, fertigation, and thinning, yielding a total of 16 different combinations (treatments). Tree vegetative growth, yield, fruit size, fruit color, firmness, soluble solids concentration, malic acid, nitrogen and calcium content, and percentage fruit with storage rot (Pezicula malicorticis) were evaluated for all 16 treatments. Changing to the novel alternative in only one or two of the areas did not produce significant improvements in all investigated parameters. The optimal treatment consisted of radical winter pruning + summer pruning (novel), bark mulching (novel), fertigation with 0.13 g N (standard), and hand thinning after full bloom (novel).
Effect of Auxin Treatments on Calyx Senescence in the Degreening of Four Mandarin Cultivars
Authors: Carvalho Catarina P. , Salvador Alejandra , Navarro Pilar , Monterde Adela , Martínez-Jávega Jose M.
Published: February 2019

The degreening process is crucial in citrus fruit for the marketing of extra-early mandarins. Nevertheless, the application of ethylene during this treatment can be associated with calyx senescence. Citrus marketing regulations do not allow either alteration to fruit quality or the presence of calyx browning, especially on product exported to the United States. In this research, four synthetic auxins were tested for control of calyx disorders caused by degreening in different Clementine cultivars: Oronules, Clemenules, Marisol, and Clemenpons. All the tested auxins reduced calyx senescence, but the best results for all cultivars were obtained by 3,5,6-trichloro-2-pyridyloxyacetic acid followed by 2,4-dichlorophenoxyacetic acid isopropyl ester. In general, the higher the doses, the smaller the calyx alterations. The most susceptible cultivar to calyx senescence was ‘Marisol’, whereas ‘Clemenules’ and ‘Clemenpons’ were the most tolerant. Treated fruit presented lower weight loss than untreated fruit. Every treatment achieved the commercial color index and no sensory alteration was observed.
Mustard (Sinapis alba) Seed Meal Suppresses Weeds in Container-grown Ornamentals
Authors: Boydston Rick A. , Anderson Treva , Vaughn Steven F.
Published: February 2019

Mustard seed meal is a byproduct of mustard (Sinapis alba L.) grown for oil production. Developing new uses for mustard seed meal could increase the profitability of growing mustard. Seed meal of mustard, var. ‘IdaGold’, was applied to the soil surface to evaluate its effect on several common weeds in container-grown ornamentals. Mustard seed meal applied to the soil surface of containers at 113, 225, and 450 g·m−2 reduced the number of annual bluegrass (Poa annua L.) seedlings by 60%, 86%, and 98%, respectively, and the number of common chickweed (Stellaria media L.) seedlings by 61%, 74%, and 73%, respectively, at 8 weeks after treatment (WAT). Mustard seed meal applied to the soil surface after transplanting Rosa L. hybrid, var. ‘Red Sunblaze’, Phlox paniculata L., var. ‘Franz Schubert’, and Coreopsis auriculata L., var. ‘Nana’ did not injure or affect the flowering or growth of ornamentals. In separate experiments, mustard seed meal applied at 225 g·m−2 to the soil surface reduced the number of emerged seedlings and fresh weight of creeping woodsorrel (Oxalis corniculata) 90% and 95%, respectively, at 8 WAT. Mustard seed meal applied at 450 g·m−2 completely prevented woodsorrel emergence at 8 WAT. Mustard seed meal applied postemergence to established liverwort (Marchantia polymorpha L.) at 113, 225, and 450 g·m−2 did not injure container-grown Pulsatilla vulgaris Mill., var. ‘Heiler Hybrids Mixed’ up to 6 WAT and controlled liverwort from 83% to 97% at 6 WAT. Weed suppression with mustard seed meal generally increased as rate increased from 113 to 450 g·m−2. Mustard seed meal may be useful for selective suppression of annual weeds when applied to the soil surface of container-grown transplanted ornamentals.
Host Status of Selected Peach Rootstocks to Meloidogyne mayaguensis
Authors: Nyczepir Andrew P. , Brito Janete A. , Dickson Don W. , Beckman Thomas G.
Published: February 2019

Six commonly known peach rootstocks (i.e., Flordaguard, Guardian®, Halford, Lovell, Nemaguard, and Okinawa) were evaluated for their susceptibility to Meloidogyne mayaguensis in the greenhouse. All rootstocks were rated as either nonhosts (highly resistant) or poor hosts (resistant) of M. mayaguensis. Lovell generally supported greater numbers of M. mayaguensis eggs per plant and eggs per gram of dry root, whereas no nematode reproduction was noted on Flordaguard rootstock (nonhost). Root galling occurred on all six rootstocks. However, reproduction as measured by number of egg masses, eggs per plant, and eggs per gram of dry root was a better measure of host resistance than number of root galls per plant.
Cover Crop Mulch and Fungicide Program Affect Development of Septoria Leaf Spot and Marketable Yield in Processing Tomato Production
Authors: Wyenandt Christian A. , Rhodes Landon H. , Riedel Richard M. , Bennett Mark A.
Published: February 2019

The development of septoria leaf spot in processing tomatoes grown on conventional (bare soil) beds or beds with chemically or mechanically killed winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) cover crop mulch with or without fungicide was examined. The two fungicide treatment programs included fungicide applied weekly (7 d) and a no fungicide control. In mulch bed systems without fungicide, septoria leaf spot caused ≈50% defoliation 10 and 28 d later in 1997 and 1998 than in the conventional system, respectively. In both years, area under disease progress curve (AUDPC) values for septoria leaf spot development were lower with the presence of a chemically or mechanically killed mulch compared with the conventional bed system when no fungicide was applied. In 1997, there were no significant differences in AUDPC values for septoria leaf spot development when fungicide was applied weekly. In 1998, AUDPC values were lower in both mulch systems compared with the conventional bed system when fungicide was applied weekly. At harvest in both years, defoliation was highest in the no fungicide control treatment. In 1997, marketable yield was significantly higher in both mulch systems compared with the conventional bed system. Conversely, in 1998, marketable yield was significantly higher in the conventional bed system than in either mulch bed system.
Suppressive Effect of Silicon Nutrient on Phomopsis Stem Blight Development in Asparagus
Authors: Lu Gang , Jian Wenlei , Zhang Jiajing , Zhou Yijing , Cao Jiashu
Published: February 2019

The effects of silicon nutrition on the resistance to stem blight caused by Phomopsis asparagi was assessed in two asparagus cultivars, UC157 and Gynlim, and the activation of defense responses in inoculated plants was measured in a greenhouse with nutrient solution culture. The supply of silicon (Si) significantly suppressed stem blight development in inoculated plants. The disease index was significantly reduced in Si-supplied plants compared with Si-deprived plants in both cultivars. Supplement with Si enhanced Si accumulation in asparagus root and shoot. Si content was significantly higher in Si-treated plants when compared with control plants, but it was not significantly different between the two cultivars. Interestingly, inoculation with P. asparagi increased Si content in shoots in the cultivar UC157. Root-applied Si significantly enhanced the activities of pathogenesis-related proteins (PRs) such as catalase, peroxidase, polyphenoloxidase, and β-1, 3-glucanase in inoculated plants. However, Si treatment mostly failed to change significantly the activity of PRs in plants without fungal attack. So continuous feeding of Si to the plant is probably important for enhancing the resistance to infection by P. asparagi in asparagus.
The Influence of Breaks in Storage Temperature on ‘Cripps Pink’ (Pink Lady™) Apple Physiology and Quality
Authors: East Andrew R. , Tanner David J. , Jobling Jenny J. , Maguire Kate M. , Mawson A. John
Published: February 2019

The maintenance of optimal storage conditions for fresh produce is rarely achieved in commercial cool chains. The impact of deviations for short time periods from these optimal storage conditions on fruit quality has not been thoroughly investigated. In this study, ‘Cripps Pink’ apples (Malus domestica) stored at 0 °C in air were exposed to periods at 20 °C (for 1, 3, and 6 days) to simulate breaks in the cool chain. The influence of harvest maturity, storage time before exposure, length of exposure, and multiple exposures to 20 °C on fruit physiology during and after the exposures was monitored through 27 laboratory-based scenario simulations. Preclimacteric apples exposed to 20 °C hastened climacteric development, whereas postclimacteric apples were induced to produce ethylene at ≈1.5 times the normal on return to cool storage at 0 °C irrespective of the fruit harvest maturity or timing, length, and number of exposures to 20 °C. The observed increase in ethylene production did not increase rates of reduction of either fruit stiffness (a measure of flesh texture) or background color measurement (hue angle). This research suggests that fluctuations in temperature have a greater effect in terms of changes in quality for preclimacteric apples than postclimacteric fruit. The reasons why changes in fruit stiffness and background hue angle in postclimacteric fruit did not respond to increases in ethylene production require further investigation.
Plant Regeneration of Periwinkle (Catharanthus roseus) via Organogenesis
Authors: Swanberg Andrea , Dai Wenhao
Published: February 2019

Two periwinkle cultivars, Pacific Coral (P1) and Sunstorm Rose (P2), were used for development of a plant regeneration system. Leaf and internodal explants collected from in vitro plants were plated onto woody plant medium (WPM) using a factorial arrangement of 6-benzyladeine (BA) and 1-naphthalene acetic acid (NAA). Shoots were successfully regenerated. Shoot production from leaf tissues was minimal for all cultivars, whereas internodal tissues showed variable rates of regeneration depending on the hormone combination. Cultivar P1 showed the maximum regeneration rate (73.3%) when internodal explants, 4 to 6 mm in length, were placed on WPM containing 5 μm BA and 5 μm NAA. Cultivar P2 showed a regeneration rate of 56.7% with a combination of 20 μm BA and 10 μm NAA. Shoot regeneration rate increased as the internodal explant size increased for P2; however, the regeneration rate decreased when the explant size was greater than 7 mm for P1. The shoot regeneration rate decreased as the period of the dark treatment of internodal explants increased in both P1 and P2. The antibiotics carbenicillin (Carb) and cefotaxime (Cef) had little effect on shoot regeneration. There was a slightly higher rate observed for P1 when Cef was added into the medium, whereas P2 showed a decrease with the addition of Cef. Carb showed no significant effect on shoot regeneration for both cultivars. Addition of both Carb and Cef to the medium slightly inhibited shoot regeneration.
Maternal Light Environment During Seed Development Affects Lettuce Seed Weight, Germinability, and Storability
Authors: Contreras Samuel , Bennett Mark A. , Metzger James D. , Tay David
Published: February 2019

Seed germinability and storability are important aspects of seed quality determined by the genotype and environment of seed development. Lettuce (Lactuca sativa L.) is produced commercially in most temperate and subtropical areas of the world. The objective of this study was to determine how photoperiod and light quality of the mother plant environment affects lettuce seed quality. Seeds of cv. Tango were produced in growth chambers under one of two treatments: a) short day (SD), consisting of 8 hours of fluorescent light (≈310 μmol·m−2·s−1) plus 16 hours of darkness daily, and b) long day (LD), consisting of 4 hours of incandescent light (≈21 μmol·m−2·s−1), 8 hours of fluorescent light, 4 hours of incandescent light, and 8 hours of darkness daily. The red to far-red ratio was ≈6.8 and 1.0 for the fluorescent and incandescent light, respectively. In both treatments, the temperature was 23 °C. The LD treatment produced significantly heavier seeds; however, germination at optimal conditions (20 °C-light) was similar for both treatments. Germinability (percentage and rates) at suboptimal conditions (30 °C, 20 °C with different external ABA concentrations, negative osmotic potentials, or dark) was higher for seeds produced under the LD treatment. On the other hand, seeds produced under the LD treatment presented better storability (evaluated by the accelerated aging test and standard germination after storage at 30 °C and 74% RH). The critical period for light environment effects was also studied. Seed weight patterns were determined early in seed development, during the first 6 days after flowering. Conversely, light environment effects on seed germinability and storability were determined at the end of seed development, after physiological maturity, which occurred by 11 days after flowering. These results show that lettuce seed germinability and storability may be modified by management of light conditions during seed production and provide useful information for seed producers, seed companies, and seed conservation institutions.
Effects of Phosphorus on Morphology and Foliar Nutrient Concentrations of Hydroponically Grown Scaevola aemula R. Br. ‘Whirlwind Blue’
Authors: Burnett Stephanie E. , Zhang Donglin , Stack Lois B. , He Zhongqi
Published: February 2019

In commercial greenhouses, fan flower ‘Whirlwind Blue’ (Scaevola aemula R. Br.) plants are sensitive to phosphorus applications in the range typically applied to other floricultural crops. To quantify this response, fan flower plants were grown in Hoagland solutions containing 0, 20, 40, 60, or 80 mg·L−1 P. Plants fertilized with either the highest (80 mg·L−1) or lowest (0 mg·L−1) P concentrations had significantly shorter stems and smaller shoot dry weights and leaf areas than plants fertilized with 20 to 60 mg·L−1 P. Low or high P concentrations negatively impacted flower number; fan flower fertilized with 0, 60, or 80 mg·L−1 P had fewer flowering branches and flowers compared with plants fertilized with 20 to 40 mg·L−1 P. Plants receiving no P had longer roots than those receiving any P and had greater root dry weights than plants receiving all other P concentrations except 20 mg·L−1. Foliar nutrient analysis indicated that although P treatments significantly impacted foliar concentrations of at least some essential macro- and micronutrients, all essential elements were within or near recommended ranges except P. Foliar P concentrations exceeded 1 mg·g−1 in fan flower that received even the lowest concentration of supplemental P, but leaf chlorosis was only observed in plants grown in 60 to 80 mg·L−1 P. As a result of rapid accumulation of P in fan flower foliage and subsequent reductions in flower number and shoot elongation, fan flower should be fertilized with no more than 20 mg·L−1 P.
Altered Light Interception Reduces Grape Berry Weight and Modulates Organic Acid Biosynthesis During Development
Authors: DeBolt Seth , Ristic Renata , Iland Patrick G. , Ford Christopher M.
Published: February 2019

The response of grape berries at a cellular level to environmental change was explored with particular emphasis on physiological changes such as weight, sugar content, and the biosynthesis of organic acids. Three levels of light were used: highly exposed, moderately exposed, and light-excluding boxes (1% ambient with no change in temperature effect). Berry weight was significantly lower in light-excluding boxes than in exposed bunch treatments. Organic acid content and berry development were followed throughout the growing season. Light exclusion resulted in a significant reduction of both tartaric acid and oxalic acid compared with highly exposed fruit, suggesting that in this experiment, light irradiance influenced accumulation of these metabolites. In contrast, malic acid was broken down postveraison at a dramatically slower rate in light exclusion treatments. The sink properties of grape berries appear to change according to the light received by the bunch. These data imply that cluster shading significantly reduced berry size and suggest the role of organic acids as osmotica.
Register of New Fruit and Nut Cultivars List 44
Authors: Finn Chad E. , Clark John R.
Published: February 2019

Crop Listingsz: Almond, Almond Rootstock, Apple, Apricot, Apricot Rootstock, Blackberry, Blueberry, Cherry Rootstock, Cherry—Sweet, Currant, Grape, Hazelnut, Nectarine, Pawpaw, Peach, Peach Rootstock, Pear—Asian, Pear—European, Pecan, Persian Walnut, Plum and Plum Hybrids, Plum Rootstock, Raspberry, Strawberry
Capsaicinoids Content in Habanero Pepper (Capsicum chinense Jacq.): Hottest Known Cultivars
Authors: Canto-Flick Adriana , Balam-Uc Eduardo , Bello-Bello Jericó Jabìn , Lecona-Guzmán Carlos , Solís-Marroquín Daniela , Avilés-Viñas Susana , Gómez-Uc Eunice , López-Puc Guadalupe , Santana-Buzzy Nancy , Iglesias-Andreu Lourdes Georgina
Published: February 2019

The aim of this study was to determine the pungency level of different accessions of Habanero peppers. The high-performance liquid chromatography (HPLC) technique was used to evaluate the content of total capsaicinoids in the whole fruit, placenta, and pericarp of 18 accessions of Habanero pepper from the germplasm bank of the Capsicum chinense species maintained in the Scientific Research Center of Yucatan [Centro de Investigación Científica de Yucatán (CICY)]. Thirteen of these accessions belonged to the “orange type”, four to the “red type”, and one to the “yellow type”. During the study, the plants were cultivated and maintained under greenhouse conditions and the fruit was harvested only when it was completely ripe on the plant. The results show considerable intraspecific diversity for this characteristic as well as the existence of cultivars of this species that surpass the levels of pungency reported for Habanero peppers under the conditions evaluated.
Potential Sources of Genetic Resistance in Lactuca spp. to the Lettuce Aphid, Nasanovia ribisnigri (Mosely) (Homoptera: Aphididae)
Authors: McCreight James D.
Published: February 2019

Lettuce aphid, Nasanovia ribisnigri (Mosely) (Homoptera: Aphididae), is an economically important pest of lettuce (Lactuca sativa L.). High-level resistance found in a wild relative, Lactuca virosa L. accession PIVT 280, is conditioned by the Nr gene, which has been transferred to European cultivars and is being commercially transferred to U.S.-adapted cultivars. New sources of resistance to guard against possible resistance-breaking strains of lettuce aphid were sought in a greenhouse screening of 1203 accessions of lettuce, which included 1047 accessions of L. sativa L., seven accessions of Lactuca perennis L., 18 accessions of Lactuca saligna L., 125 accessions of L. serriola L., and six accessions of L. virosa L. Two new and potentially unique sources of resistance to lettuce aphid were found in L. serriola accession PI 491093 and L. virosa accession PI 274378. The genetic relationship of resistance in PI 491093 and PI 274378 with that in PIVT 280 remains to be determined.
Wine Grape Response to Foliar Particle Film under Differing Levels of Preveraison Water Stress
Authors: Shellie Krista , Glenn D. Michael
Published: February 2019

We investigated how foliar application of kaolin particle film influenced diurnal leaf gas exchange, leaf water potential, yield, and berry maturity of a red (‘Merlot’) and white (‘Viognier’) wine grape (Vitis vinifera L.) cultivar under differing levels of water stress over two growing seasons (2005 and 2006) in the warm, semiarid climate of southwestern Idaho. Net diurnal stomatal conductance (g
S) was increased by particle film and the effect varied according to vine water status. Particle film delayed the onset of diurnal decline in g
S under mild water stress (leaf water potential ≈ –1.2 MPa) but had no influence on leaf gas exchange when vines were under greater water stress (leaf water potential ≈ –1.4 MPa). Correlation between soluble solids concentration and titratable acidity (‘Viognier’) and between berry fresh weight and yield (‘Merlot’) was higher with than without particle film, suggesting that particle film may attenuate the influence of other factors affecting expression of these traits. Particle film was associated with an increase in berry weight in ‘Merlot’ and with an increase in berry soluble solids concentration in ‘Viognier’, suggesting that the film may increase vine-carrying capacity. Midday leaf water potential throughout the growing season was not influenced by particle film. Fruit surface browning was observed on deficit-irrigated, particle film-treated vines on exposed clusters on the west side of the canopy, indicating that the film did not eliminate development of heat stress symptoms on fruit under the most extreme environmental conditions evaluated in this study.
Temperature and Pseudobulb Size Influence Flowering of Odontioda Orchids
Authors: Blanchard Matthew G. , Runkle Erik S.
Published: February 2019

Odontioda is a cool-growing, sympodial epiphytic genus of orchids originating from the Andes Mountains of South America. Several hybrids are commercially grown as potted flowering plants for their brightly colored flowers and compact growth habit. We quantified how constant and fluctuating day/night temperatures influenced inflorescence initiation, time from visible inflorescence (VI) to flower, and pseudobulb development. Odontioda George McMahon ‘Fortuna’ and Lovely Penguin ‘Emperor’ were grown at constant temperature set points of 14, 17, 20, 23, 26, or 29 °C and day/night (12 h/12 h) temperatures of 20/14, 23/17, 26/14, 26/20, 29/23, or 29/17 °C. Plants were grown in glass greenhouses under a 12-h photoperiod and a maximum irradiance of 500 μmol·m−2·s−1. Within 6 weeks, heat stress symptoms such as leaf necrosis were observed on plants grown at a day temperature of 26 °C or greater regardless of the night temperature. After 20 weeks, 90% or greater of both clones had a VI when grown at a constant temperature of 14 or 17 °C. Plants grown at a constant temperature of 17 °C had the greatest pseudobulb diameter with a mean increase of 3.5 to 4.0 cm. In all treatments, a minimum pseudobulb diameter was required for uniform inflorescence initiation; pseudobulbs with a diameter of 5.5 cm or greater developed a VI in 93% of plants. Data for time from VI to open flower were converted to a rate, and a thermal-time model relating temperature with inflorescence development was developed. The base temperature and thermal time for VI to flower in George McMahon ‘Fortuna’ and Lovely Penguin ‘Emperor’ were estimated at −0.1 °C and 1429 °C·d−1 and 0.8 °C and 1250 °C·d−1, respectively. This information could be used by commercial orchid growers to assist in producing potted flowering Odontioda orchids for specific market dates.
Productivity, Oil Content, and Oil Composition of Sweet Basil as a Function of Nitrogen and Sulfur Fertilization
Authors: Zheljazkov Valtcho D. , Cantrell Charles L. , Ebelhar M. Wayne , Rowe Dennis E. , Coker Christine
Published: February 2019

Nitrogen (N) and sulfur (S) were believed to be important nutrient management tools for the production of sweet basil (Ocimum basilicum L. ‘German’) with desirable oil content and composition and acceptable herbage yields. A multilocation research study was initiated to evaluate the effect of N (0, 60, 120, and 180 kg·ha−1 N) and S (0, 20, 40, and 80 kg·ha−1 S) rates on biomass production, oil content, and oil composition for sweet basil. The three locations in Mississippi (Stoneville, Poplarville, and Verona) were selected based on soil type, geographic, and climatic variation. Location, N rate, and their interaction were significant on basil dry herbage yields. The herbage yield means were 4967 kg·ha−1, 2907 kg·ha−1, and 2122 kg·ha−1 for Poplarville, Verona, and Stoneville, respectively. Oil content was significantly affected by location with means of 0.69%, 0.80%, and 0.64% for Stoneville, Poplarville, and Verona, respectively. Location, N, and S had significant effects on oil yields with means of 14.7, 38.7, and 18.5 kg·ha−1 for Stoneville, Poplarville, and Verona, respectively. The significant quadratic response of essential oil yields to N fertilization rates showed oil yields were maximized for fertilization between 50 and 60 kg·ha−1 N. In contrast, the response to S fertilization appeared to continue to increase beyond the maximum fertilization rate evaluated of 80 kg·ha−1 S. Location and N application rates had a significant effect on the yields of the major basil oil constituents (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol, whereas S had a significant effect on eucalyptol yield only. Eucalyptol concentration was positively correlated to the concentration of (–)-bornyl acetate. This is the first study to quantify (in real concentration) the response of the major sweet basil oil constituents (–)-linalool, eugenol, (–)-bornyl acetate, and eucalyptol as a function of N and S application rates. Also, it is the first study to demonstrate a strong response of basil oil yield to S. The results from this study demonstrated that N and S applications can be used as management tools with respect to sweet basil production, oil content, and oil composition.
Nutrient Management with Cover Crops and Compost Affects Development and Yield in Organically Managed Sweetpotato Systems
Authors: Treadwell Danielle D. , Creamer Nancy G. , Hoyt Greg D. , Schultheis Jonathan R.
Published: February 2019

A 3-year field experiment was initiated in 2001 to evaluate different organic sweetpotato production systems that varied in cover crop management and tillage. Three organic systems: 1) compost and no cover crop with tillage (Org-NCC); 2) compost and a cover crop mixture of hairy vetch and rye incorporated before transplanting (Org-CCI); and 3) compost and the same cover crop mixture with reduced tillage (Org-RT) were compared with a conventionally managed system (Conv) with tillage and chemical controls. Yield of No. 1 sweetpotato roots and total yield were similar among management systems each year, except for a reduction in yield in Org-RT in 2002. The percentage of No. 1 grade roots was at least 17% and 23% higher in Org-CCI and Org-NCC than Org-RT in 2001 and 2002, respectively, and similar to Conv in 2001 and 2004. Organic and conventional N sources contributed to soil inorganic N reserves differently the 2 years this component was measured. In 2002, soil inorganic N reserves at 30 DAT were in the order: Org-CCI (90 kg·ha−1) > Org-NCC (67 kg·ha−1) > Org-RT (45 kg·ha−1), and Conv (55 kg·ha−1). No differences in soil inorganic N reserves were observed among systems in 2004. Sweetpotato N, P, and K tissue concentrations were different among systems only in 2004. That year, at 60 days after transplanting, tissue N, P, and K were greatest in Org-CCI. In 2001 and 2004, N (4.09% to 4.56%) and K (3.79% to 4.34%) were higher than sufficiency ranges for N (3.2% to 4.0%) and K (2.5% to 3.5%) defined by North Carolina Department of Agriculture and Consumer Services recommendations for all treatments. No tissue macronutrient or micronutrient concentrations were limiting during this experiment. Reduced rainfall during the 2002 sweetpotato growing season may have contributed to the low microbially mediated plant-available N from the organic fertilizer sources. Despite differences in the nutrient content of organic and conventional fertility amendments, organically managed systems receiving compost with or without incorporated hairy vetch and rye produced yields equal to the conventionally managed system.
Remediation of Iron Chlorosis by the Addition of Fe-o,o-EDDHA in the Nutrient Solution Applied to Soilless Culture
Authors: Urrestarazu Miguel , Alvaro Juan E. , Moreno Soraya , Carrasco Gilda
Published: February 2019

The aim of this study was to evaluate the remediation of ferric chlorosis using by iron (Fe)-o,o-EDDHA in fertigation of soilless crops compared with Fe-EDTA (ethylene diamine tetra acetic acid) and its effects on production. Two separate greenhouse experiments were conducted in slab or bag cultures using the tomato (Lycopersicon esculentum Mill. cv. Daniela) and green bean crops (Phaseolus vulgaris L. cv. Maite) in Almería (southeast Spain). The crops were subjected to the following experimental setup: 1) At first phase, all plants were treated with a standard nutrient solution and Fe was supplied as Fe-EDTA. 2) No Fe was supplied in the nutrient solution to bean crops 46 days after transplanting. For tomato plants, this element was eliminated from the nutrient solution since 102 days after transplanting. In this phase, Fe-EDTA was supplied to the control plants (T1). This phase was ended when signs of ferric chlorosis appeared on the leaves. 3) The ferric chlorosis was remediated with either Fe-EDTA (T2) or Fe-o,o-EDDHA (T3). The T4 group did not receive any supplements. The total tomato and bean production was improved after the Fe deficiency had been corrected by either EDTA and Fe o,o-EDDHA supplements in the fertigation of these crops. The synthetic Fe o,o-EDDHA chelate alleviated Fe deficiency by increasing the amount of iron in the rhizosphere and its supply to the leaves and petioles. Consequently, the decrease in tomato and bean production resulting from ferric chlorosis could be prevented. As a conclusion, the remediation of ferric chlorosis through fertigation with Fe o,o-EDDHA is as effective as the use of traditional Fe-EDTA.
Plant and Environmental Factors Influencing the Pattern of Pigment Accumulation in ‘Honeycrisp’ Apple Peels Using a Novel Color Analyzer Software Tool
Authors: Telias Adriana , Hoover Emily , Rother Diego
Published: February 2019

One of the most important factors determining apple (Malus pumila P. Mill.) market acceptance is peel color. Coloring of ‘Honeycrisp’ fruits can adopt two patterns: blushed or striped. This is an unusual phenomenon in apple. The objective of this study was to compare ‘Honeycrisp’ fruit from trees that were propagated from buds occurring on branches carrying only blushed or striped fruit. We concluded that blushed trees tend to produce a higher percentage of blushed fruit than striped trees, indicating a mechanism conserved through cell division. The percentage of blushed fruit on any given tree changed from year to year. Blushed and striped fruit occurred together on the same branch, and even on the same spur, with fruits located in the outer canopy being more likely to be striped. Higher crop loads were associated with a lower percentage of blushed fruit on the tree. Blushed and striped fruit do not consistently differ in their maximum pigment accumulation before ripening. The comparison of average hue angle for the whole peel at harvest indicates that blushed fruit are redder on average. Stripes were caused by reduced anthocyanin accumulation in certain portions of the peel and not by deeper localization. We speculate that an epigenetic mechanism regulates the pattern of anthocyanin accumulation in ‘Honeycrisp’ apple. Increased production of blushed, redder apples may be achieved through clonal selection and crop load regulation. A software tool for efficient relative color evaluations was developed and is freely available to the community.
Effects of Timing of CPPU Applications on Rabbiteye Blueberries
Authors: NeSmith D. Scott
Published: February 2019

A series of field and greenhouse experiments were conducted at two locations in Georgia to determine how rabbiteye blueberries (Vaccinium ashei Reade) respond to different timings of application of the growth regulator [N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU)]. In all tests, a CPPU rate of 15 mg·L−1 was used, and timings of applications were based on days after flowering (DAF). Overall, results indicate that a positive response in fruit set or berry size can occur with applications of CPPU depending on cultivar and timing of application. As with many growth regulators, the effect can vary, and these experiments indicate that the timing of CPPU application is critical in achieving the most desirable response. Collectively, data suggest an optimum window of application of CPPU to rabbiteye blueberries is between 7 and 21 DAF with the most probable success being from an application made around 14 ± 3 DAF.
Public Funding for Research into Specialty Crops
Authors: Alston Julian M. , Pardey Philip G.
Published: February 2019

Specialty crops have become increasingly important relative to other categories of agricultural production in the United States over the past 50 years, especially during the past 25 years. The growth in the value of production of specialty crops has not been matched by commensurate growth in public agricultural research spending. The specialty crops' share of spending on crops research (or on all agricultural research) has remained approximately constant during a period when the specialty crops' share of the value of production has increased significantly. This article reviews trends in the economic importance of specialty crops, and public funding for specialty crops research, and examines arguments and evidence about whether the total funding for specialty crops research is too little and whether the share of agricultural research funding allocated to specialty crops should increase. Although the evidence is mixed, we conclude that specialty crops research is underfunded and that a case can be made for increasing the share of agricultural research funding going to specialty crops. A producer check-off program with a matching government grant could be developed to give incentives to both the industry and the government to help enhance research funding.
Characterization of Stigma Exudates in Aqueous Extracts from Apple and Pear Flowers
Authors: Lawrence Pusey P. , Rudell David R. , Curry Eric A. , Mattheis James P.
Published: February 2019

The stigmatic secretions of pomaceous flowers serve as a natural medium not only for pollen, but also for the pathogen Erwinia amylovora (Burr.) Winslow et al. and other microorganisms. To understand the microecology on the stigma, exudates from cultivars of pear (Pyrus communis L.), apple (Malus pumila P. Mill.), and crab apple [Malus mandshurica (Maxim.) Kom.] were analyzed for free sugars and free amino acids as available carbon and nitrogen sources. Extracts were obtained at different stages of anthesis by submerging and sonicating stigmas in water. Certain free sugars (glucose and fructose) and free amino acids (proline, asparagine, glutamic acid, and glutamine) were consistently predominant and increased during anthesis. Apple stigma extracts were also analyzed for polysaccharides and proteins. Of major components identified for apple, free sugars made up 4.5% by mass; polysaccharides (composed of arabinose and galactose), 49.6%; and proteins, 45.9%. The two largest components are likely present as glycoproteins. This may be the first report on characteristics of rosaceous stigma exudates that includes the identity of specific free sugars, free amino acids, and polysaccharide subcomponents. Discussion includes the comparison of pomaceous stigma exudates to those of other plants and the microecological implications.
Using Color Infrared Imagery to Detect Sooty Mold and Fungal Pathogens of Glasshouse-propagated Plants
Authors: Summy Kenneth R. , Little Christopher R.
Published: February 2019

Fungi are major biotic constraints for optimum production and quality of glasshouse plants. When plants are infested with sooty mold (Capnodium spp.) or infected with pathogens, the reflected wavelengths of the electromagnetic spectrum are altered. Spectroradiometric measurements and color infrared (CIR) images of control, honeydew-coated, and sooty mold-infested saplings and individual leaves from trifoliate orange (Poncirus trifoliata), sour orange (Citrus aurantium), ‘Valencia’ orange (C. sinensis), and ‘Bo’ tree (Ficus religiosa) were obtained. Grapefruit saplings and individual leaves infected with Mycosphaerella citri (greasy spot) were imaged under glasshouse conditions. Similarly, muskmelon foliage showing low and high levels of powdery mildew (Sphaerotheca fuliginea) disease severity were analyzed. When examining individual leaves, all fungal biotic stressors generally resulted in variable spectral reflectance data, especially in the blue (450 nm) and green (550 nm) wavelengths; however, values in the red (650 nm) tended to increase and values in the near-IR (850 nm) tended to decrease with stress. Near-IR/red image ratios were significantly reduced (P < 0.05) in stressed whole plant foliage and individual leaves relative to healthy controls. The accumulation of insect honeydew (which occurs before sooty mold infestation) significantly increased (P < 0.05) near-IR reflectance values and near-IR/red ratios in ‘Valencia’ orange and near-IR/ratios in ‘Bo’ tree foliage and individual leaves. Image acquisition and enhancement techniques may prove useful in large-scale production greenhouses where existing infrastructure and high plant populations require high throughput data analysis and identification of biotic stressors.
Development of Tuber Blight (Phytophthora infestans) on Potato Cultivars Based on In Vitro Assays and Field Evaluations
Authors: Nyankanga Richard O. , Olanya Ocen Modesto , Wien Hans C. , El-Bedewy Ramzy , Karinga John , Ojiambo Peter S.
Published: February 2019

Tuber blight may result from infection of wounded or unwounded potato tubers exposed to sporangia from foliar blight, soil, or blighted tubers. However, there are limited data on the prediction of tuber blight in field or storage environment based on in vitro assays. To assess this relationship, potato cultivars with foliar blight resistance (R-genes) and general resistance were evaluated for tuber blight incited by Phytophthora infestans (US-1) based on wound-induced and unwounded tuber inoculations. Surface lesion diameter, lesion depth, and frequency distribution of blighted tubers were assessed in in vitro assays and tuber blight incidence determined in field experiments. Significant differences (P < 0.05) in lesion diameter and depth were recorded among cultivars. Surface lesion diameter, depth, and index ranged from 5 to 40, 2 to 16.3, and 15 to 656 mm, respectively, in wound-inoculated tubers. In nonwounded tuber assays, the incidence of blighted tubers ranged from 0% to 8.7% in both years. Tuber blight infection of potato cultivars varied between years in field studies. Although tuber infection differed among cultivars, the frequency of blighted tubers had a normal statistical distribution irrespective of R-genes, implying that foliar resistance may have limited effect on tuber blight occurrence based on in vitro experiments. Prediction of tuber blight based on inoculation assays can be effectively used to estimate and manage blight development in storage environments.
Temperature Prior to Harvest Influences the Incidence and Severity of Clubroot on Two Asian Brassica Vegetables
Authors: McDonald Mary Ruth , Westerveld Sean M.
Published: February 2019

Shanghai pak choy [Brassica rapa L. subsp. chinensis (Rupr.) var. communis Tsen and Lee] and Chinese flowering cabbage [Yow choy; B. rapa L. subsp. chinensis (Rupr.) var. utilis Tsen and Lee] were seeded into organic (muck) soil naturally infested with the clubroot pathogen (Plasmodiophora brassicae Woronin) at the University of Guelph Muck Crops Research Station, Ontario, Canada, in June, July, and Aug. 2001 and May, June, July, and Aug. 2002. At harvest, clubroot incidence and disease severity index (DSI) were assessed. Data from 17 different seedings at the research station over 4 years were used to compare the relationship between disease incidence and DSI and weather conditions during crop development. Clubroot incidence and severity were highest for crops harvested in July and August and lowest for crops harvested in October. Mean air temperatures during crop development ranged from 15 to 22 °C and were positively correlated with clubroot incidence and severity for both pak choy (r = 0.68) and flowering cabbage (r = 0.73). The strongest correlations occurred between air temperatures and disease severity over the final 10 d before harvest (r = 0.82 for pak choy; r = 0.84 for flowering cabbage). The research suggests that clubroot damage in Asian Brassica vegetables could be minimized by seeding in early spring and late summer in areas infested with P. brassicae.