bluuebunny/crossref_metadata_2025 huggingface dataset:
Micropropagation of Agave americana
Authors: Chen Ying , Chen Xinlu , Hu Fei , Yang Hua , Yue Li , Trigiano Robert N. , Cheng Zong-Ming (Max)
Published: February 2019

Agave species are economically important plants in tropical and subtropical desert ecosystems as ornamentals as well as potential bioenergy crops. However, their relatively long life cycles and the current lack of biotechnology tools hinder their breeding. In this study, an efficient system for micropropagation was developed for Agave americana L. by using basal stems as explants and grown on a modified Murashige and Skoog medium (MSI) or a 1/2 MSI medium supplemented with various concentrations of 6-benzylaminopurine (BA) for shoot proliferation. The highest number of shoots (18.5 shoots/explant) from basal stems was obtained on MSI supplemented with 13.32 μM BA. An efficient shoot regeneration system was also developed from leaf tissues. Combinations of auxin with cytokinin, basal media, and leaf regions were optimized for shoot induction. Adventitious shoot formation from leaf segments was induced and proliferated with combination ranging of 0.54 to 2.68 μM [α-naphthaleneacetic acid (NAA)] with 8.88 to 13.32 μM (BA), and the maximum frequency (≈69%) was obtained with 2.68 μM NAA plus 13.32 μM BA. MSI medium and the basal segment of leaf affected shoot induction. The highest rooting frequency and mean number of shoots occurred in 1/2 MSI containing with 4.92 μM indole-3-butyric acid (IBA) alone (90%, 3.4) or 1.48 μM IBA plus 1.61 μM NAA (92%, 5.2). Survival of in vitro plantlets after transfer and acclimatization to ex vitro conditions was 87%. This is the first complete protocol for micropropagation of A. americana.
Fertilizer Rate and Type Affect Sedum-vegetated Green Roof Mat Plant Performance and Leachate Nutrient Content
Authors: Clark Mary Jane , Zheng Youbin
Published: February 2019

This study compared the effect of fertilizer rates and types on plant performance and leached nutrients for an installed sedum-vegetated green roof mat system. Sedum-vegetated mats in non-fertilized plots (control) were compared with plots fertilized with 16N–2.6P–10K plus Minors 5–6 month controlled-release fertilizer (CRF) at 5, 10, 15, or 20 g·m−2 nitrogen (N) or 5 g·m−2 N of a fly-larvae processed chicken manure (Sus). Plot overall appearance was among the highest for 10 g·m−2 N in Mar., May, June, and July 2012, whereas 15 and 20 g·m−2 N resulted in the highest winter injury ranking in Mar. 2012. Vegetative coverage was highest for 10 and 15 g·m−2 N in Oct. 2011 but did not differ among treatments in 2012. Sedum spp. composition within plots remained closest to the original when fertilized at 10 g·m−2 N. Of all species, S. acre flowered for the longest duration and flowered longer in 10 g·m−2 N than 15 g·m−2 N or Sus. Leaf greenness of S. acre for 5, 10, 15, and 20 g·m−2 N was higher than the control in May 2012. Leached amounts of NH4+, NO3–, potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), and aluminum (Al) did not differ among treatments, and cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), and lead (Pb) were not detected. All nutrients but NO3– in all plots and zinc (Zn) in the 5 g·m−2 N (CRF and Sus) and control plots were leached at levels above target nutrient loss thresholds. Among fertilizer types, Sus leached more phosphorus (P) without greater plant performance compared with 5 g·m−2 N CRF. A fertilizer rate of 10 g·m−2 N is recommended to benefit plant performance of this green roof system. However, in the first year after installation, to prevent negative environmental impacts resulting from initial substrate fertility, no fertilizer (CRF or Sus) is needed for this green roof system.
The Effects of Gibberellic Acid on Sex Expression and Secondary Sexual Characteristics in Papaya
Authors: Han Jennifer , Murray Jan E. , Yu Qingyi , Moore Paul H. , Ming Ray
Published: February 2019

The vegetative forms of male (XY), female (XX), and hermaphrodite (XYh) papaya (Carica papaya L.) plants are phenotypically identical. However, the flower and inflorescence morphology of each sex type is unique. Gynodioecious varieties SunUp, SunUp Diminutive mutant, and dioecious AU9 were used to test the response of papaya to gibberellic acid (GA3). Exogenous applications of GA3 on female and hermaphrodite flowers of papaya did not yield any sex reversal phenotype but caused a significant increase in peduncle elongation and inflorescence branch number in all treated plants. An increase in flower number was seen in females but not hermaphrodites or males. There was an increase in plant height for all treated plants except SunUp Diminutive mutant, suggesting that the mechanism causing the dwarf phenotype is independent of gibberellins. Gibberellin metabolism genes were identified in the papaya genome, none of which mapped to the sex-determining region of either the male- or hermaphrodite-specific region of papaya Y or Yh chromosome. We hypothesize that a transacting regulatory element that enhances gibberellin biosynthesis plays a role in the extreme length of the male papaya peduncle.
Apple Compositional and Peel Color Differences Resulting from Canopy Microclimate Affect Consumer Preference for Eating Quality and Appearance
Authors: Hamadziripi Esnath T. , Theron Karen I. , Muller Magdalena , Steyn Willem J.
Published: February 2019

We hypothesized that the microclimate at different positions in the tree canopy may affect the appearance, eating quality, and consumer preference for apple fruit. Hence, the aim of this study was to evaluate the internal and external quality of inner and outer canopy apples in relation to consumer preference for the eating quality and appearance of these fruit. We determined peel color, flesh firmness, percentage starch breakdown, soluble solids concentration (TSS), titratable acidity (TA), and dry matter concentration (DMC) for inner and outer canopy ‘Starking’, ‘Golden Delicious’, and ‘Granny Smith’ from the Ceres region in South Africa in the 2009–10 and 2010–11 seasons. We also determined reducing sugars, total phenolics, and total antioxidant capacity in the 2009–10 season. A trained panel assessed the sensory characteristics of fruit while consumers were asked to indicate their liking for the eating quality and appearance of fruit. Outer canopy fruit of all three cultivars had higher antioxidant capacity, TSS, DMC, lower TA, and were generally sweeter than inner canopy fruit. Consumers could discern eating quality differences and generally preferred the eating quality of outer canopy fruit. The appearance of outer canopy fruit was not preferred in the “green” cultivars, probably as a result of the unfamiliarity of consumers with such fruit. Consumers did, however, prefer the redder outer canopy to the less red inner canopy ‘Starking’ fruit. The redness of ‘Starking’ fruit in this study can therefore be seen as a true signal of eating quality, i.e., the redder the fruit, the better the eating quality, and this would probably apply to other fully red and bicolored apple cultivars. Hence, the classification of red cultivars into different quality classes based on the extent of red color development seems justified from an eating quality perspective. In contrast, blushed outer canopy ‘Granny Smith’ and ‘Golden Delicious’ are culled for aesthetic reasons. It might be possible to develop a niche local market for these blushed fruit based on their better eating quality. Our data were generated in older orchards with trees planted at low density and with large canopies. Planer, two-dimensional canopies are likely to reduce the differences between inner and outer canopy fruit. Differences in macroclimate or in fruit maturity between seasons may also have an overbearing effect on fruit quality parameters compared with canopy microclimatic conditions.
Effect of Light Intensity and Nutrition Level on Growth and Flowering of Adenium obesum ‘Red’ and ‘Ice Pink’
Authors: McBride Kaitlyn , Henny Richard J. , Chen Jianjun , Mellich Terri A.
Published: February 2019

Adenium obesum (Forssk.), Roem. & Schult., commonly known as desert rose, is a high-value, container-grown ornamental plant produced worldwide for its bright floral display and striking sculptural caudex. Little scientific-based information exists regarding the effect of light intensity and nutritional levels on Adenium growth and flowering. In this study, A. obesum ‘Red’ and ‘Ice Pink’ were grown under full sun [with a measured maximum photosynthetically active radiation (PAR) of 1850 μmol·m−2·s−1], 30% shade (1255 μmol·m−2·s−1), or 50% shade (943 μmol·m−2·s−1) in 1.25-L pots top-dressed with controlled-release fertilizer Nutricote® Plus (18N–2.6P–6.6K) at rates to provide 0.4, 0.9, or 1.4 g of nitrogen (N) per pot. Canopy height and width, flower number, and visual quality ratings (based on plant size and form, foliage color, and flowering) were highest after 16 weeks of growth for both cultivars when fertilized with 1.4 g of N per pot. A 30% shade level resulted in plants with the highest flower numbers and quality ratings. Plants grown at 50% shade had the greatest canopy heights and widths, but flower numbers and quality ratings were low. In full sun, plants were smaller overall. In a second experiment, A. obesum ‘Red’ produced the highest shoot dry weight when grown 20 weeks at 30% or 50% shade with 1.4 g of N per pot. Root formation is an important measure of aesthetic value for this crop. As plants mature, roots enlarge dramatically and are often washed to expose sculptural forms. The highest root dry weights were measured at 1.4 g of N under both full sun and 30% shade.
Effects of Foliar Sulfur Sprays on Pecan Independent of Pecan Scab Control
Authors: Wells Lenny , Brock Jason , Brenneman Tim
Published: February 2019

Many commercial pecan [Carya illinoinensis (Wangenh.) K. Koch] producers routinely spray foliar urea and sulfur (S) in combination with their fungicide sprays, despite very little information available in the scientific literature regarding the effects of these practices on pecan production. The objectives of this study were to investigate the effects of foliar application of elemental S and urea, alone and in combination, on pecan leaf tissue nitrogen (N) and S concentration, pecan nut quality, leaf chlorophyll index (LCI), and pecan scab control. Foliar S sprays increased pecan nut weight over the control in 2 of 3 years of study. Pecan nut weight was unaffected by foliar urea sprays compared with the control, but nut weight was lower for foliar urea sprays compared with foliar S sprays in the first 2 years of study. Neither foliar S nor urea sprays affected pecan scab incidence or severity. Foliar S sprays failed to increase leaf S concentration throughout the study. Pecan leaf N and leaf S concentrations were lower in the foliar urea treatment than in the control and foliar S treatments during the initial year of study; however, no treatment differences were observed for urea after Year 1. Foliar S application enhanced LCI in 2011 and 2012. Leaf chlorophyll index was also increased by the combination of foliar urea and S in 2012. These results suggest that foliar S sprays may provide pecan producers with a tool with which to maximize nut size and increase the profitability of their crop.
Yield of Two Hydroponically Grown Tomato Cultivars as Affected by Transplanting Stage or Direct Seeding
Authors: Maboko Martin Makgose , Du Plooy Christian Phillipus
Published: February 2019

Direct seeding or transplanting younger seedlings should reduce costs in hydroponic systems. A 2-year study (2011–12 and 2012–13) was conducted to determine yield of two hydroponically grown tomato cultivars using transplanted seedlings at different growth stages vs. direct seeding. An open bag, using 10-L plastic bags filled with sawdust, was used for direct seeding and transplanting of seedlings at two-, four- or six-leaf stages. Data were collected on early marketable, early total, total, total marketable and cull yield as well as plant fresh and dry mass. In 2011–12, there was increased early marketable and total yields from direct-seeded plants or plants transplanted at the two- or four-leaf stage. Cultivar FA593 produced a higher early marketable yield and total yield compared with ‘Linares’. In 2012–13, the highest early marketable and total yields were for plants developed from those transplanted at the two-leaf stage or from those developed from direct seeding. There was no difference between cultivars on marketable and total yield. Cultivar Linares produced the highest plant fresh and dry mass. Early yield can be induced by direct seeding or transplanting seedlings at the two-true leaf stage with no significant effect on total yield and marketable yield. Direct-seeded plants, or transplanting seedlings at the two-leaf stage, will benefit growers by producing tomatoes earlier for the market while eliminating or reducing transplant shock.
Supplemental Lighting Orientation and Red-to-blue Ratio of Light-emitting Diodes for Greenhouse Tomato Production
Authors: Deram Paul , Lefsrud Mark G. , Orsat Valérie
Published: February 2019

Current greenhouse supplemental lighting technology uses broad-spectrum high-pressure sodium lamps (HPS) that, despite being an excellent luminous source, are not the most efficient light source for plant production. Specific light frequencies in the 400- to 700-nm range have been shown to affect photosynthesis more directly than other wavelengths (especially in the red and blue ranges). Light-emitting diodes (LEDs) could diminish lighting costs as a result of their high efficiency, lower operating temperatures, and wavelength specificity. LEDs can be selected to target the wavelengths used by plants, enabling growers to customize the light produced, to enable maximum plant production and limit wavelengths that do not significantly impact plant growth. In our experiment, hydroponically grown tomato plants (Solanum lycopersicum L.) were grown using a full factorial design with three light intensities (high: 135 μmol·m−2·s−1, medium: 115 μmol·m−2·s−1, and low: 100 μmol·m−2·s−1) at three red (661 nm) to blue (449 nm) ratio levels (5:1, 10:1, and 19:1). Secondary treatments for comparison were 100% HPS, 100% red LED light supplied from above the plant, 100% red LED light supplied below the plant, a 50%:50% LED:HPS mixture, and a control (no supplemental lighting). Both runs of the experiment lasted 120 days during the Summer–Fall 2011 and the Winter–Spring 2011–12. The highest biomass production (excluding fruit) occurred with the 19:1 ratio (red to blue) with increasing intensity resulting in more growth, whereas a higher fruit production was obtained using the 5:1 ratio. The highest marketable fruit production (fruit over 90 g) was obtained with the 50%:50% LED:HPS followed by 5:1 high and 19:1 high. Consistently the 5:1 high performed well in every category. LEDs have been shown to be superior in fruit production over HPS alone, and LEDs can improve tomato fruit production when mixed with HPS. LEDs provide a promising mechanism to enhance greenhouse artificial lighting systems.
Exogenous Abscisic Acid Increases the Anthocyanin Concentration of Berry and Juice from ‘Isabel’ Grapes (Vitis labrusca L.)
Authors: Koyama Renata , Marinho de Assis Adriane , Yamamoto Lilian Yukari , Borges Wellington Fernando , de Sá Borges Rogério , Prudêncio Sandra Helena , Roberto Sergio Ruffo
Published: February 2019

Vitis labrusca grapes are widely cultivated in some countries such as Brazil and the United States, especially for juice production. ‘Isabel’ is one of the main cultivars because of its high production and disease tolerance, but the juice is deficient in color. The objective of this study was to evaluate the effect of timing and concentration of (S)-cis-abscisic acid (S-ABA), a specific isomer of abscisic acid applied to ‘Isabel’ grapes, aiming to increase anthocyanin accumulation and to improve juice quality. The trial was conducted on two consecutive seasons (2011 and 2012) in a commercial vineyard located in Maringa, PR, Brazil. The vines were trained in an overhead trellis system and spaced at 4.0 × 1.0 m. The statistical model used was a randomized block design with four replications and five treatments: control; S-ABA at 200 mg·L−1 at 7 days after veraison (DAV); S-ABA at 400 mg·L−1 at 7 DAV; S-ABA at 200 mg·L−1 at 7 DAV + 200 mg·L−1 at 15 days after the first application (DAFA); and S-ABA at 400 mg·L−1 at 7 DAV + 400 mg·L−1 at 15 DAFA. There were no significant differences between treatments in relation to berry or cluster size or weight. S-ABA application resulted in increased anthocyanin concentrations in both berries and juices, mainly when 400 mg·L−1 was applied. Sensory analysis also revealed the efficiency of this plant growth regulator to promote better acceptance of grape juices. Thus, a single application of S-ABA at 400 mg·L−1 at 7 DAV is sufficient to increase the anthocyanins concentration of ‘Isabel’ grapes, improving the acceptance of juice by consumers.
Somaclonal Variation in Habanero Pepper (Capsicum chinense Jacq.) as Assessed ISSR Molecular Markers
Authors: Bello-Bello Jericó J. , Iglesias-Andreu Lourdes G. , Avilés-Viñas Susana A. , Gómez-Uc Eunice , Canto-Flick Adriana , Santana-Buzzy Nancy
Published: February 2019

Intersimple sequence repeat (ISSR) markers were used to evaluate the effects of in vitro culture on genetic variation in Habanero pepper (Capsicum chinense Jacq.) regeneration protocols. A total of 219 ISSR clear and reproducible fragments were generated with 13 ISSR primers in direct organogenesis, direct and indirect somatic embryos, and the embryogenic callus system. A cluster analysis was performed to express in the form of dendrogram the relationships among different regeneration systems and the genetic variability detected. Genetic distance analysis indicated that our regeneration protocols are inappropriate for micropropagation, conservation, or genetic transformation; however, they may be applicable to breeding. This is the first report on the use of molecular analysis to evaluate genetic variation of in vitro-regenerated plants of Habanero pepper using ISSR markers.
Flower Bud Formation of Sacred Lotus (Nelumbo nucifera Gaertn.): A Case Study of ‘Gyozankouren’ Grown in a Container
Authors: Ishizuna Fumiko , Tsutsumi Nobuhiro
Published: February 2019

The genus Nelumbo consists of two species, N. nucifera and N. lutea. N. nucifera is an ornamental and edible plant that is widely cultivated. Earlier studies of sacred lotus (N. nucifera) flowers focused mainly on morphology, phyllotaxis, leaf arrangements, and flower development. During the growing season, sacred lotus produces one foliage leaf at each node. Flower buds emerge from the abaxial side of the basal part of the foliage leaf. However, the number of blooming flowers is much less than the number of foliage leaves. Little is known concerning flower bud formation during lotus plant development. This is the first experimental study to reveal that every node has one flower bud even in the dormant shoot apex and that most of the formed flower buds aborted in the course of floral development. Our results suggest that flower bud formation of sacred lotus is independent of daylength. On the other hand, whether a formed bud reaches blooming may depend on environmental factors.
Genetic Relatedness among Dendrobium (Orchidaceae) Species and Hybrids Using Morphological and AFLP Markers
Authors: Wahba Lydia E. , Hazlina Nor , Fadelah A. , Ratnam Wickneswari
Published: February 2019

Dendrobium is one of the largest genera in the Orchidaceae family. Information on the genetic diversity and relationships among species and hybrids is important for breeding purposes and species conservation. The objectives of this study were to assess genetic relatedness and to determine whether morphological, molecular, or combined analysis can discriminate among Dendrobium species, commercial hybrids, and interspecific hybrids. A total of 81 Dendrobium accessions were characterized with 12 amplified fragment length polymorphism (AFLP) primer pairs and 21 morphological characters. Mean genetic relatedness for morphological characters, AFLP analysis, and combined analysis were 0.61, 0.37, and 0.43, respectively. Dendrograms were generated using an unweighted pair group method with arithmetic averages (UPGMA); the analysis was performed on a Jaccard similarity coefficient matrix. The data from morphological characters revealed that the Jaccard similarity coefficient ranged from 0.20 to 1.0, where the tested 81 Dendrobium accessions could be grouped into four clusters. For the AFLP analysis, the number of polymorphic fragments for each primer varied from 80 to 284 with 78% average percentage of polymorphic loci and the similarity coefficient ranging from 0.125 to 1.0 with Dendrobium accessions grouped into three clusters. The similarity coefficients estimated through a combined analysis of morphological and AFLP data ranged from 0.21 to 1.0 and the Dendrobium accessions appeared clustered into two groups. The results revealed some similarities among the three data sets. The combined data set was the most useful in discriminating Dendrobium accessions based on species sections and relationship among species and their hybrids. The correlation between the AFLP data and the combined data was highly significant (r = 0.98, P > 0.001), indicating the usefulness of AFLP data for species discrimination and hybrid identity in the absence of floral morphological characters.
Inorganic Nitrogen Nutrition Enhances Osmotic Stress Tolerance in Phaseolus vulgaris: Lessons from a Drought-sensitive Cultivar
Authors: Sassi-Aydi Sameh , Aydi Samir , Abdelly Chedly
Published: February 2019

The nitrogen (N) requirement of legumes can be met by inorganic N assimilation and symbiotic N2 fixation. Both N assimilation routes have diverse influences on drought tolerance because of the differences in the use of energy and the reduction in power characteristics of those pathways. We investigated N nutrition under osmotic stress and likely criteria conferring tolerance to osmotic stress in common bean. Osmotic stress tolerance in a drought-sensitive common bean cultivar (Coco blanc) was compared with beans relying on N nutrition, N2 fixation, or fertilization with urea. Osmotic stress was applied by means of 25 (mild stress), 50 (moderate stress), or 75 (severe stress) mm mannitol for 15 days. At the end of the stress period, relative water content, total N contents, total soluble sugars, total chlorophyll, total protein, and potassium were assayed. Urea-fed plants grew better and had better tolerance to osmotic stress. This was attributed to maintaining higher N use efficiency, better leaf hydration, and adequate osmoregulation.
Vegetative Growth of Three Southern Highbush Blueberry Cultivars Obtained from Micropropagation and Softwood Cuttings in Two Florida Locations
Authors: Marino Silvia R. , Williamson Jeffrey G. , Olmstead James W. , Harmon Philip F.
Published: February 2019

Field performance of southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrids) cultivars Emerald, Jewel, and Primadonna derived from softwood cuttings (SW) and tissue culture (TC) was evaluated in Citra and Haines City, FL, in 2010–12. Both fields were planted in Apr. 2010 on sandy soil amended with pine bark. Plant height and width were recorded at both locations, from which plant canopy volume was calculated. Additionally, whole plants were harvested at planting and after the first growing season, after the first fruit harvest, and after the second growing season. Average plant height and width, number of major canes, and total shoot number were determined at each sampling date. Dry weights for roots, crowns, canes, shoots, and leaves were obtained. Although propagation method affected plant canopy volume during the first season, no effects were observed by the end of the second growing season. At planting and after the first and second growing seasons, TC plants of the three cultivars had more major canes. Total shoot number per plant was greater for TC ‘Jewel’ at all dates but ‘Emerald’ TC plants had more shoots only at planting and after the first growing and harvest seasons. Tissue culture resulted in increased plant dry weights of ‘Jewel’ and ‘Emerald’ after the first and second growing seasons. There were no significant differences in total number of shoots or plant dry weight between TC and SW-derived ‘Primadonna’ plants at any point during the study.
Grow Tubes Change Microclimate and Bush Architecture but Have Little Effect on Bush Biomass Allocation at the End of the Establishment Year in Blueberry
Authors: Tarara Julie M. , Chaves Bernardo , Strik Bernadine C.
Published: February 2019

Microclimate variables were integrated over a 6-month period during which blueberry (Vaccinium corymbosum cv. Liberty) bushes were grown in 51-cm high, 20-cm diameter round grow tubes (opaque or translucent) on a sawdust mulch-covered raised bed with the mulch incorporated into tilled soil. Grow tubes were installed around plants in the spring of 2006, 5 months after planting. Total photosynthetic photon flux (PPF) density was 55% and 21% of ambient in translucent and opaque tubes, respectively. Daily maximum vapor pressure deficit consistently was highest in translucent tubes. Air (Ta) and stem (Tstem) temperatures in both grow tube types exceeded Ta and Tstem in non-tubed plants (ambient). Maximum mulch surface temperature (Tm) was lowest in opaque tubes, whereas there was no difference in Tm between ambient and translucent tubes. The soil–mulch interface temperature (Tsm) was warmer outside tubes than Tsm inside tubes. Soil temperatures directly under the tubes differed very little between tube types and ambient, generally less than 1 °C. Root and crown dry mass (DM) did not differ between tubed plants and ambient at the end of the establishment year. Leaf area, leaf DM, and fruit bud number were suppressed inside tubes. All plants were greater than 51 cm tall at the end of the growing season. Substantial compensatory growth occurred above tubes: tubed plants were more upright and had more leaf area, leaf DM, and shoot growth than ambient plants above 51 cm. However, there was no difference between tubed and ambient plants in fruit bud number, total plant leaf area, shoot:root, or DM of 1- and 2-year-old wood. Grow tubes can alter microclimate and architecture of young blueberry bushes but have no significant influence on size and distribution of total DM after one growing season in the field.
Susceptibility of Peach Cultivars to Rusty Spot and Characterization of Susceptibility Groups
Authors: Lalancette Norman , Ward Daniel L. , Goffreda Joseph C.
Published: February 2019

A field study was conducted during the 2007 and 2008 growing seasons to determine and compare the susceptibility of 33 peach (Prunus persica L. Batsch) cultivars and advanced selections to rusty spot caused by Podosphaera leucotricha. During each season, the progression of peach rusty spot was monitored on three cultivars of varying susceptibility to determine when the epidemics had terminated. At that time, disease incidence and severity were estimated as percent infected fruit and number of lesions per fruit, respectively, for all cultivars in the study. Observations were recorded on fruit sampled from four replicate trees of each cultivar located in experimental plantings at the Rutgers Agricultural Research and Extension Center, Bridgeton, NJ. No fungicide sprays were applied to the trees during the study. Overall disease incidence values, estimated by averaging data from both years, varied widely across cultivars, ranging from 5% to 68% fruit infected. The three most susceptible cultivars were Autumnglo, Jerseyqueen, and Bounty, whereas the three least susceptible cultivars were Gloria, Harrow Beauty, and Sugar May. Results of Tukey-Kramer mean separation groupings and relative susceptibility rankings across both years were used to place cultivars into five disease susceptibility categories. The most susceptible cultivars were characterized as having yellow flesh with normal melting flesh texture and acidity, whereas less susceptible cultivars tended to have white-fleshed stony-hard subacid fruit. Among eight quantitative fruit characteristics examined for association with disease levels, ripening date, fruit weight at pit hardening, and fruit pubescence were found to be positively correlated with rusty spot development. Finally, the relationship between disease incidence and lesion density within the 0 to 0.5 incidence range, based on data from all cultivars in the study, agreed closely with former models derived from only a single cultivar.
Groundcover Management and Nutrient Source Effects on Soil Carbon and Nitrogen Sequestration in an Organically Managed Apple Orchard in the Ozark Highlands
Authors: Mays N. , Brye K.R. , Rom Curt R. , Savin M. , Garcia M.E.
Published: February 2019

Orchards established on weathered, acidic mineral soils in the Ozark Highlands must be managed to meet tree nutritional requirements. However, a common characteristic of Ozark Highland soils is a relatively low soil organic matter (SOM) concentration, a condition that can have detrimental effects on orchard productivity. Organic orchard management poses specific challenges to managing competitive under-tree vegetation and supplying appropriate supplemental nutrition to maintain tree growth and cropping. In Mar. 2006, an experimental apple orchard was established to evaluate the effects of under tree, in-row groundcover management system (i.e., shredded paper, wood chips, municipal green compost, and mow-blow), and nutrient source (i.e., non-fertilized control, composted poultry litter, and pelletized organic commercial fertilizer) on SOM, carbon (C), and nitrogen (N) concentration, and soil C and N sequestration over time in an organically managed orchard in the Ozark Highlands region of northwest Arkansas. Soil organic matter, total C, and total N concentrations (soil weight basis) and contents (area basis) in the top 7.5 cm increased in all groundcover management systems from 2006 to 2011. The greatest differences were observed with municipal green compost treatments. Significant interactions between groundcover management treatment and nutrient source were only observed for SOM concentration, whereas nutrient source did not affect total C and total N concentrations or contents. Soil C sequestration rates were 0.9, 1.0, and 2.8 Mg·ha−1 per year under the shredded paper, wood chip, and green compost treatments, respectively, whereas total C content did not change over time under the mow-blow treatment. The green compost treatment was the only treatment that had significant total N sequestration occur (0.25 Mg nitrogen/ha/year). Results of this study indicate that organic cultural methods can significantly augment near-surface soil C and N contents, which will likely increase productivity, of apple orchards in the Ozark Highlands over a relatively short period time after establishment. This study has implications for orchards in similar soils or environmental circumstance and for both organic and conventional management systems.
Flowering Patterns of Pollenizer and Triploid Watermelon Cultivars
Authors: McGregor Cecilia E. , Waters Vickie
Published: February 2019

The past 10 years has seen a steep increase in production of seedless watermelon (Citrullus lanatus) in the United States. Seedless fruit is produced on triploid plants that require pollination from diploid pollenizers for fruit set. Synchronization of the staminate flowers on the pollenizers with the appearance of pistillate flowers on the triploids is a fundamental requirement for this production system. Previous research suggested that pistillate flowers reach peak production early in the season, but data are only available for a small number of triploid cultivars. We compared the flowering patterns of 29 triploid cultivars and 20 pollenizers, including 10 harvested pollenizers, during the first 6 weeks after transplanting over 2 years. The average number of days from transplanting (DAT) to the first staminate flower was between 5.3 days and 19.1 days in 2012 and 9.7 days and 24.4 days in 2013 for the pollenizers and between 18.7 days and 27.6 days and 22.1 days and 32.7 days for the pistillate triploid flowers in the 2 years, respectively. K-means clustering of the weekly percentage of plants with staminate and pistillate flowers for the different cultivars shows that different triploid and pollenizer cultivars have different flowering patterns and that some combinations have better synchronized flowering than others. Growers should take particular care when choosing pollenizers for early-flowering triploid cultivars. Harvested pollenizers are better suited to late-flowering triploids and growers should choose triploid and pollenizer cultivar combinations with flowering patterns that best satisfy their specific production goals.
Russeting and Relative Growth Rate Are Positively Related in ‘Conference’ and ‘Condo’ Pear
Authors: Scharwies Johannes Daniel , Grimm Eckhard , Knoche Moritz
Published: February 2019

Russeting is an important surface disorder in fruit and mechanical growth stresses, among other factors, are considered causal in russet induction. To test this hypothesis, fruit development and russeting were monitored on a whole fruit level and also in the calyx, cheek, and neck region of developing ‘Conference’ and ‘Condo’ pear fruit (Pyrus communis L.). To quantify growth, the pear fruit was geometrically modeled as approximating to half of a prolate spheroid for the calyx region and two truncated cones for the cheek and neck regions, respectively. Mass and surface area of ‘Conference’ and ‘Condo’ fruit increased in a single sigmoidal pattern with time. Fruit volume, determined by buoyancy, using a hydrostatic balance, and the Archimedes’ principle was closely related to that predicted by the model from fruit geometry. Growth rates of surface area in ‘Conference’ and ‘Condo’ peaked at ≈90 and 100 days after full bloom (DAFB), respectively, and were highest in the calyx followed by the cheek and neck regions. Relative growth rates, calculated by dividing growth rates by the absolute surface area present at that time, were at maximum during early development and thereafter continuously declined. In general, relative growth rates were highest for the cheek region, intermediate in the calyx, and lowest for the neck. ‘Conference’ fruit were always more russeted than ‘Condo’ with russeting generally decreasing from calyx to cheek and neck. Furthermore, russeting increased rapidly in ‘Conference’ during early development until ≈70 DAFB, particularly in the calyx and cheek regions and, to a lesser extent, in the neck region. There was little change in russeting after ≈70 DAFB. Plotting rates of russeting vs. relative growth rates in surface area indicate a positive and common relationship across regions where russeting increased when relative growth rates exceeded 0.03/day. Thus, differential growth rates between regions within ‘Conference’ or ‘Condo’, but not across the two cultivars, accounted for topical differences in russeting.
Impact of Cluster Thinning and Basal Leaf Removal on Fruit Quality of Cabernet Franc (Vitis vinifera L.) Grapevines Grown in Cool Climate Conditions
Authors: Zhuang Shijian , Tozzini Letizia , Green Alan , Acimovic Dana , Howell G. Stanley , Castellarin Simone D. , Sabbatini Paolo
Published: February 2019

Achieving desired fruit quality at harvest in cool climate conditions is a challenge, especially for red varieties, and the typical inability of fruit to reach technological maturity is a critical contributing factor requiring examination. To probe this issue, this research investigated the impact of two levels of crop thinning and of basal leaf removal at three phenological stages in the 2011 and 2012 growing seasons in Michigan. Experiments were conducted at the Southwest Michigan Research and Extension Center (SWMREC) in Benton Harbor. Using ‘Cabernet franc’ (Vitis vinifera L.) vines, yield components (yield per vine, pruning weight, and cluster and berry weight) and basic fruit composition traits [total soluble solids (TSS), pH, titratable acidity, anthocyanins, and phenolics) were studied to investigate the effect of cluster thinning and basal leaf removal on vine performance and fruit quality at harvest. Neither of the treatments significantly impacted TSS in either of the two seasons. Cluster thinning treatment successfully altered cropload ratio, indexed as Ravaz Index (RI), independently of the time of application. Basal leaf removal increased exposed berry temperature, cluster light exposure, and subsequent anthocyanin and phenolic content of the berry in both seasons, again independent of application date, whereas cluster thinning was effective only in 2012. Crop thinning coupled with basal leaf removal resulted in an increased efficiency in anthocyanin accumulation in relation to TSS accumulation, expressed as anthocyanin:sugar, in both years. This is significant because it offers potential for vineyard management practices aiming to improve fruit quality in cool climates where the onset of anthocyanin accumulation could be reduced and decoupled from sugar accumulation.
Effects of S-Abscisic Acid and (+)-8′-Acetylene Abscisic Acid on Fruit Set and Stomatal Conductance in Apple
Authors: McArtney Steven J. , Abrams Suzanne R. , Woolard Derek D. , Petracek Peter D.
Published: February 2019

Fruit set of apple can be reduced by cloudy weather, short-term shade treatments, or application of photosynthetic inhibitors when the young fruit are ≈8 to 15 mm in diameter, indicating that fruit are sensitive to a transient carbohydrate stress during this period. We investigated the potential for S-abscisic acid (ABA) and an ABA analog [(+)-8′-acetylene ABA] to chemically thin apple fruit by causing a stomatal limitation of photosynthesis. Stomatal conductance (gS) of ‘Imperial Gala’/M.7 was reduced by 60% 3 h after application of 250 mg·L−1 ABA or 25 mg·L−1 (+)-8′-acetylene ABA. Stomatal conductance began to recover 4 days after application but did not return to control levels until 19 days after treatment. Application of 250 mg·L−1 ABA combined with 100 mg·L−1 6-benzyladenine (6-BA) when mean fruit diameter was ≈10 mm reduced fruit set of ‘Gala’/M.7 but not ‘Pink Lady™’/M.7 or ‘Morganspur Delicious’/MM.111. Fruit set of ‘Pink Lady™’/M.7 was reduced by application of 20 mg·L−1 (+)-8′-acetylene ABA + 100 mg·L−1 6-BA at full bloom or 10 mg·L−1 (+)-8′-acetylene ABA + 100 mg·L−1 6-BA at the 10-mm fruit diameter stage. Fruit set of ‘Morganspur Delicious’/MM.111 was reduced by application of 25 mg·L−1 (+)-8′-acetylene ABA, either alone or in combination with 75 mg·L−1 6-BA, at the 10-mm fruit diameter stage. ABA and (+)-8′-acetylene ABA triggered leaf abscission at rates above 250 mg·L−1 and 25 mg·L−1, respectively. Fruit set and gS data from the present studies indicate the biological activity of (+)-8′-acetylene ABA is 10-fold higher than ABA. These results suggest that ABA and (+)-8′-acetylene ABA reduced fruit set by causing a stomatal limitation in photosynthesis that resulted in a transient carbohydrate stress. Thinning responses to ABA and (+)-8′-acetylene ABA at the concentrations used in these experiments were reduced compared with standard concentrations of currently available chemical thinning agents. However, increasing the concentration of ABA or (+)-8′-acetylene ABA to levels that would achieve comparable thinning are also likely to result in unacceptable leaf abscission.
Essential Oil Yield and Composition of Garden Sage as a Function of Different Steam Distillation Times
Authors: Zheljazkov Valtcho D. , Astatkie Tess , Shiwakoti Santosh , Poudyal Shital , Horgan Thomas , Kovatcheva Natasha , Dobreva Anna
Published: February 2019

Garden sage (Salvia officinalis L.) is a medicinal, culinary, ornamental, and essential oil plant with a wide range of ecological adaptation. Garden sage essential oil traditionally is extracted by steam distillation from the above-ground biomass and has widespread applications as an aromatic agent in the food and pharmaceutical industries as well as in perfumery and cosmetics. The hypothesis of this study was that the steam distillation time (DT) may significantly affect essential oil yield and composition of garden sage and, therefore, DT could be used as a tool to obtain oil with different composition. Therefore, the objective was to evaluate the effect of various steam DTs (1.25, 2.5, 5, 10, 20, 40, 80, and 160 minutes) on garden sage oil yield and composition. Most of the oil in the garden sage dry herbage was extracted in 10-minute DT; extending DT up to 160 minutes did not significantly increase oil yields. Overall, 39 oil constituents were identified in the garden sage essential oil. Fourteen oil constituents with the highest concentration in the oil were selected for statistical analyses. Monoterpenes represented the major percentage (58.2% to 84.1%) of oil composition followed by sesquiterpenes (4.0% to 16.1%) and diterpenes (0.3% to 7.6%). Overall, the monoterpene hydrocarbons (α-pinene, camphene, β-pinene, myrcene, and limonene) were eluted early in the steam distillation process, which resulted in their high concentration in the oil at 5- to 10-minute DT and relatively low concentrations in the oil obtained at 160-minute DT. In general, the concentration of sesquiterpenes (β-caryophyllene, α-humulene, and verdifloral) increased with increasing duration of the DT and reached their respective maximum concentrations in the oil at 160-minute DT. The relative concentrations of major constituents, camphor and cis-thujone, in the oil obtained at 2.5-minute DT were higher than in the oils obtained at longer DT. Therefore, if oil with high concentrations of camphor and cis-thujone is desirable, garden sage dried biomass ought to be steam distilled for 2.5 to 5 minutes and the oil collected. If oil with a high concentration of monoterpene hydrocarbons and a high concentration of oxygenated monoterpenes is desirable, then garden sage should be distilled for 20 minutes. If oil with a high concentration of the diterpene manool is desirable, then garden sage should be steam-distilled for 80 minutes. If oil with a high concentration of sesquiterpenes is desirable, then garden sage should be steam-distilled for 160 minutes. The duration of steam distillation can be used as an economical method to obtain garden sage oil with a different chemical composition. The regression models developed in this study can be used to predict garden sage oil yield and composition distilled for various amounts of time and to compare literature reports in which different durations of DT were used.
Effects of Ripening Stage, Temperature, and Film Wrapping on the Elasticity Index as Determined by a Nondestructive Resonance Vibration Method and Fruit Quality in ‘Irwin’ Mango
Authors: Fumuro Masahiko , Sakurai Naoki
Published: February 2019

We examined the effects of ripening stage, temperature, film wrapping, and storage period on the elasticity index (EI) and fruit quality of ‘Irwin’ mangos to develop a storage technique for improving the storage life of this fruit and to determine whether flesh firmness can be estimated using the EI. The second resonant frequency measured between the two sides of the fruit was nearly equal to measurements between the dorsal and ventral surfaces of the fruit. The EI declined as fruit ripening progressed and was not influenced by fruit size. Fruits harvested at the pre-natural fruit drop stage (pre-NFDS; 2 to 3 days before fruit drop) and the post-natural fruit drop stage (post-NFDS) were kept at 25 °C for 10 days. No significant differences were detected between fruits at these two stages in terms of the EI and flesh firmness, except that both variables at the pre-NFDS were higher than those at the post-NFDS after 0 and 4 days and after 0 day of storage, respectively. Similarly, no significant differences were found between fruits at these two stages in terms of total sugar and organic acid contents, regardless of the length of the storage period. Fruits harvested at pre-NFDS were individually wrapped in low-density polyethylene film (11 μm thick) and stored at 10, 15, 20, and 25 °C for 10 days. The EI of fruits kept at 10 °C was higher than that of fruits stored at 15 to 25 °C regardless of the presence of film wrapping. At 10 °C storage, the EI of film-wrapped fruits was higher than that of non-film-wrapped fruits. Film-wrapped fruits harvested at pre-NFDS were stored at 10 °C for 30 days. After 15 days in storage, relatively rapid and then gradual declines in both the EI and flesh firmness were observed. Sugar content was unaffected by the storage period, but organic acid content decreased after 30 days in storage. A strong positive correlation was found between the EI and flesh firmness. When the data set was limited to fruits less than 20 N·cm−2 in flesh firmness and more than 350 g in weight, the correlation coefficient was higher compared with a data set with all fruit combined. The results of this study indicate that flesh firmness in ‘Irwin’ mangos can be estimated by measuring the EI. Moreover, the ripening stage, storage temperature, and film wrapping affected the retention of fruit quality.
Effects of Substrate Salinity and Nutrient Levels on Physiological Response, Yield, and Fruit Quality of Habanero Pepper
Authors: Urrea-López Rafael , Díaz de la Garza Rocío I. , Valiente-Banuet Juan I.
Published: February 2019

Although habanero peppers (Capsicum chinense, Jacq.) are highly appreciated as a result of their organoleptic and pungency properties, the crop faces edaphic stresses throughout Mexico. A study was conducted to determine how the photosynthetic parameters, vegetative growth, yield, and fruit quality of the plant change in response to suboptimal conditions in the substrate. Habanero plants were grown in an inert substrate (perlite) and exposed to increased salinity levels (4 and 7 dS·m−1) and reduced nitrogen and phosphorus conditions. Plants grown with a Hoagland-based solution were used as controls. High salinity conditions reduced the light-saturated photosynthetic rates (64% of the control) but did not compromise yield or fruit quality. This effect was possibly the result of the addition of Ca2+, which reduced salinity-induced calcium deficiency. Although comparable low nitrogen levels in previous studies were shown to cause a severe reduction in plant viability, in our study, low nitrogen reduced the light-saturated photosynthetic rates (47% of the control) and shoot:root ratio (67% of the control) but did not significantly affect yield or fruit quality. Low nitrogen and 7-dS·m−1 treatments increased fructose and glucose content (increases of 27% and 21%, respectively). Low phosphorus significantly affected plant growth and yield and reduced fructose content (73% of the control). Plants were not sensitive to low nitrogen and high salinity, possibly as a result of the use of nitrate-based fertilizers and the addition of calcium, respectively. These results provide guidelines for habanero pepper production under suboptimal edaphic conditions.