bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Different Types of Daylily Explants for Somatic Embryogenesis
Authors: Chen* Lianghong , Gosukonda Ramana , Carter Johnny
Published: February 2019

To improve somatic embryogenesis of Daylilies (Hemerocallis hybrid); six types of explants namely immature seeds, immature embryos, mature embryos, young inflorescence, ovary-sections and filaments of daylily flower buds were investigated as source of explants. Explants from field grown plants were surface sterilized and followed by culturing on MS medium supplemented with 1.5 mg/L NAA and 0.5 mg/L BAP for four weeks. Explants were scored for development of embryogenic tissue and formation of somatic embryos with/without the formation of an intermediate callus stage. Both mature and immature embryo explants produced direct development of embryogenic tissue followed by somatic embryos. Young inflorescence explants developed compact calli and produced roots around cut ends and showed no somatic embryogenesis. Ovary explants exhibited swelling and not produced embryogenesis. Production of embryogenic callus and formation of somatic embryos in filament explants depended on the sizes of flower buds. Explants from 0.5 to 1.2 mm size flower buds produced calli and formed somatic embryos while explants from sizes over 1.2 mm flower buds only non-embryogenic calli. Immature seeds failed to grow. The results indicated that immature and mature embryos and filaments from young flower buds responded better than other explants for developing somatic embryos in daylily.
The Gene slm1-1 Regulates Abscission, Dehiscence, Meristem Arrest, and Apical Dominance in Arabidopsis thaliana
Authors: Dotson* Bradley , Rey Camila , Kim Joonyup , Patterson Sara
Published: February 2019

Cell separation regulates basic developmental processes such as abscission and dehiscence and is one of the horticultural traits first to be selected by mankind. Abscission is characterized by an active cell separation process where organs are detached from the main body of the plant through the dissolution of the middle lamella. Crops with early abscission can have significant reduction in yield. For example, canola, Brassica napus, loses 5% to 10% of crop due to early pod shatter. By screening T-DNA mutagenized populations of A. thaliana for delayed abscission, we have identified several genes that regulate cell separation, slm1-1 (slender lasting inflorescence and meristem) is one such genes. During our investigation of slm1-1 we have employed phenotypic, physiological, genetic, and molecular assays. Phenotypically, slm1-1 displays traits such as delayed abscission of floral organs, lack of anther pollen dehiscence (making slm1-1 functionally male sterile), delayed meristem arrest, and strong apical dominance. Phenotypic characterization includes scanning electron microscopy, bright field microscopy, and stereoscope microscopy. Physiological assays include reporter gene expression and break strength analyses. Genetically, slm1-1 is regulated by a single recessive gene. Molecular assays characterizing slm1-1 include TAIL-PCR, RT-PCR, and preliminary microarray of abscission zones. We have also begun to map based cloning of slm1-1. We believe that understanding genes that regulate cell separation in A. thaliana will contribute to crop improvement. Applications could include reducing loss during harvesting, regulation of pollination, changes in branching patterns, and longevity of flowering.
Almond Spur Autonomy: Leaf Growth, Floral Initiation and Spur Survival
Authors: Heerema* Richard J. , De Jong Ted M. , Weinbaum Steven A.
Published: February 2019

Spurs are the primary bearing unit in mature `Nonpareil' almond (Prunus dulcis (Mill.) D.A. Webb) trees. Our objective was to determine whether almond spurs behave autonomously with respect to various biological activities throughout the season. If autonomous, a spur's carbohydrate demands are met primarily by its own leaves and, therefore, the sink to source ratio of the spur itself is expected to be closely linked to its growth and development. In these experiments almond spurs differing in leaf area and/or fruit number were monitored for leaf development, fruit set, floral initiation, spur survival and carbohydrate storage. Previous-season spur leaf area had no relation to the number of leaves preformed within the dormant vegetative bud or final spur leaf area in the current season, but spurs which fruited in the previous season began spring leaf expansion later and current-season spur fruiting was associated with lower spur leaf area. There was little or no relationship between final percentage fruit set at the spur level and spur leaf area in either the current or previous seasons. Current-season spur leaf area was positively related to both spur flower bud number and spur winter survival. Carbohydrate storage in dormant spurs increased with increasing previous-season spur leaf area. These data are consistent with the concept of spur autonomy especially with regards to spur activities late in the season. The relationships of some of these same spur parameters to spur light exposure are currently being investigated.
The Relationship Between Fatty Acid Composition and Cold Hardiness of Pecan Cultivars
Authors: Bafeel* Sameera , Matta Frank
Published: February 2019

Temperature is a major environmental factor governing the distribution of both wild and cultivated plant species. During acclimation and deacclimation plants undergo a series of metabolic changes that lead to cold hardiness or loss of hardiness. One of these changes is the accumulation of certain lipids. This research was conducted to compare hardiness among three pecan cultivars: `Desirable', `Jackson', and `Owens' growing under Mississippi condition and to determine the relationship between fatty acid levels and cold hardiness of pecan shoots. Differential thermal analysis (DTA), electrical conductivity, and tetrazolium tests were used to determine cold hardiness. Pecan stems were collected from September to March in 2002 and 2003 to determine cold acclimation and deacclimation. Fatty acid composition of pecan stems during this time period was determined by gas chromatography. DTA indicated that pecan stems acclimated in October and deacclimated in March. During cold acclimation, there was a shift in the fatty acid composition to more unsaturated fatty acids. The percentage of linoleic and linolenic fatty acids increased, while the percentage of palmitic and stearic fatty acids decreased. The correlation between unsaturated fatty acids and cold hardiness suggests that unsaturated fatty acid may play a role in membrane fluidity.
Do Early Progress Grade Reports Change Student Performance in a Required, Introductory Horticulture Course?
Authors: Rom* Curt R.
Published: February 2019

In a required introductory horticulture course during a 5-year period, students received early progress grades 1/3rd of the way through the course reflecting 20% of the possible points to be awarded in the class. It was thought that student knowledge of their grade performance may result in changes in behavior and class performance. The early progress and final grades both had a bell-shaped distribution with 45% and 48% of students receiving grades better than “C” for early progress and final grades, respectively. There was a significant although low correlation between early progress grades and final grades for the course (r2 = 0.58). About 50% of the students received a final grade equal to the early progress grades, and 27% received grades higher than the early progress grades. The greatest change in performance were students who received a “D” early progress grade; 60% of those students improved their final grade. Nearly 25% of the students received final grades lower than the early progress grades. Of students receiving failing early progress grades (12%), nearly 60% withdrew from the course and only 10% received passing final grades.
Contrasting Demographics of Nontraditional Students in Two Off-Campus Horticulture Degree Programs
Authors: Fitzpatrick* George , Moore Kimberly
Published: February 2019

The Academic Program at Fort Lauderdale (APF), founded in 1984, and the Academic Program at Homestead (APH), founded in 2000, were established to enable place bound students to earn the Univ. of Fla. B.S. degree in horticulture. Although both programs are located within 60 miles of each other in the same general geographical area in southeastern Florida, there are significant demographic contrasts, as well as some similarities, between them. According to data published by the U.S. Census Bureau, the area defined by a 10-mile radius around the site of the APH has a population of ≈83,500, while the same area at the site of the APF has a population of more than 1,100,000, a 13-fold difference. The student profile at the two programs indicates a higher enrollment at APF, a higher average student age at APH, and a higher distance traveled to attend class at APF. Similarities include a student body comprised of people working in the horticultural industry who are working to earn a B.S. degree for career advancement, as well as an increasing number of students who are not currently working in horticulture but who are planning a career change.
Reaching Midwest Organic Growers through On-farm Partnerships
Authors: Delate* Kathleen , DeWitt Jerald
Published: February 2019

Based on citizen demand, Iowa State Univ. (ISU) established the first organic specialist faculty position at a U.S. Land Grant Univ. in 1997, as a shared appointment in the departments of horticulture and agronomy, with a 70% Extension and 30% Research split. A series of Organic Agriculture Focus Groups was convened in 1998 to help direct the new organic research and Extension program at ISU. Partnerships with the Leopold Center for Sustainable Agriculture and the College of Agriculture facilitated the ISU sustainable agriculture Extension leader and organic specialist's participation in an extensive focus group dialogue with a diverse group of farmers (organic and conventional), agribusiness professionals, bankers and consumers in six agricultural communities across Iowa. Paramount in the needs assessment was the establishment of organic research sites, both on-farm and at research stations across the state, to demonstrate the economic and environmental benefits associated with organic farming practices over the long term. Specific outcomes-based Extension needs were articulated, which led to the development of an annual schedule of organic workshops, field days and conferences. In 2001, in a survey of 300 farmers, 90% of respondents reported an increase in soil quality and 67% reported a 6 to 30% increase in farm income as a result of organic farming practices. The success of Land Grant Univ. organic programs will be dependent upon administrative support, sufficient resources, and community involvement in the decision-making process.
Taste Panel Perception of Sweetness as it Correlates to Refractometer Measurements and HPLC Analysis of Sugar Content
Authors: Hale* Teri , Hassell Richard , Phillips Tyron
Published: February 2019

Taste panel perception and preference of sweetness in three phenotypes (su, se and sh2) of sweet corn harvested at three maturities (early, mature and late) were compared to refractometer measurements and HPLC analysis of fructose, sucrose, and glucose. Panelist rating of sweetness and acceptability significantly correlated with HPLC analysis. These correlations were found for sucrose and total sugars present (for sweetness, r2 = 0.70 and 0.61; acceptability, r2 = 0.64 and 0.55). Sucrose significantly correlated with the total sugars present (r2 = 0.95). The panelists' perception of flavor also correlated significantly with the amount of sucrose present and total sugars (r2 = 0.66 and 0.59, respectively). Sucrose content was significantly different between se, sh2 and su, with sh2 having the highest level. Taste panels indicated this difference but showed not significant differnece between se and sh2 acceptablity. Su was only acceptable to panelists at early maturity. °Brix did not reflect the taste panels scores and HPLC measurements postively. Soluble solids and taste panel scores were negatively correlated in both the panel's perception of sweetness and acceptability (r2 = -0.66 and -0.66, respectively) which indicates that as panel scores decreased °Brix increased. Comparison of soluble solids to HPLC analysis, indicate that °Brix was negatively correlated to sucrose and total sugar content, and that as soluble solids increased, the sucrose or total sugar concentration remained constant or decreased. Soluble solids measurements have been positively correlated with sucrose levels in other crops; but this was not the case with sweet corn.
Research and Development on Genetic Resources in Non-heading Chinese Cabbage
Authors: Hou Xi-Lin , Caq Shou-Chun , Jiang* Zhong-Chun
Published: February 2019

It reviewed the research and development on genetic resources in non-heading Chinese cabbage (Brassica campestris L. ssp.chinensis Makino var. communis Tsen et Lee) achieved during the past 50 years. Researches were carried out on the methodology and classification of horticultural crops, investigation and collection of the genetic resources and development of new cultivars. Further studies were conducted on the morphological and biological characteristics, identification and analysis of disease resistance and genetic model of main economic characteristics. On these bases, 13 new cultivars were selected and spread to 800,000 hm2.
Cold and Hot Rhizome Storage Affects Growth and Flowering of Ornamental Gingers
Authors: Paz* Maria P. , Kuehny Jeff S. , Criley Richard
Published: February 2019

Ornamental gingers are popular cut flowers and have been promoted as a promising potted flower crop because of unique foliage, long-lasting colorful bracts, and few pest problems. Rhizomes are the primary means of propagation in late spring followed by shoot growth and flowering, and plants enter dormancy under short days in the fall. Termination of dormancy is important for greenhouse forcing and extending the growing season. Dormancy of storage organs can be terminated prematurely by temperature. Rhizomes of three ginger species (Curcuma alismatifolia Gagnep., C. cordata L., and Globba winittii C.H. Wright) were stored for 0,1, or 2 weeks at 10 or 15 °C followed by 0,1, or 2 weeks at 25, 30, or 35 °C to determine the effect on growth and flowering. Upon completion of treatment application, rhizomes were planted in a peat moss: bark: perlite mix and placed in a greenhouse with 25 °C day/21 °C night temperatures with 40% shade. Rhizome cold storage in combination with hot storage affected growth and development of ornamental gingers. Days to emergence (DTE) and days to flower (DTF) for Globba were hastened when rhizomes were stored for 3 weeks at 15 °C followed by 3 weeks at 30 °C. For C. alismatifolia, DTE and DTF were hastened when rhizomes were stored for 3 weeks at 10 °C followed by 3 weeks at 30 °C. For C. cordata, DTE and DTF were hastened with rhizome storage of 2 weeks at 10 °C followed by 3 weeks at 35 °C.
Refining Ornamental Heat Zone Categories with Evapotranspiration
Authors: Sutherland* Albert , Schnelle Mike , Arndt Derek
Published: February 2019

The American Horticulture Society (AHS) Heat Zone categories have been developed to categorize ornamental plant adaptability to different air temperature climates. These zones, like the Plant Hardiness map showing plant cold hardiness zones within the United States, are primarily north to south zones. Within the Great Plains region of the United States, the AHS Heat Zone categories provide a basic level of plant adaptability to air temperature, but do not account for plant reaction to variations in wind, relative humidity or sunlight. Daily reference evapotranspiration provides a single number that responds to variations in air temperature, wind, relative humidity and sunlight. In Oklahoma, the Oklahoma Mesonet provides a uniform statewide network of weather monitor towers that can be used to accurately calculate both short and tall American Society of Civil Engineers (ASCE) reference evapotranspiration (ref ET) across the entire state. Accumulated daily ref ET values can be used to provide further refinement in categorizing ornamental plant adaptability.
Effects of Reduced Fall and Winter Irrigation on Citrus Fruit Quality
Authors: Parsons* Larry R. , Etxeberria Ed
Published: February 2019

Earlier work has shown that moderate water deficits imposed on citrus trees can increase fruit Brix without adversely affecting yield. Increased water restrictions have been imposed on citrus growers as Florida's population continues to increase. The objectives of this study were to determine: 1) the effects of no irrigation in the fall and winter on orange fruit quality parameters in Florida; and 2) amount of potential irrigation water savings. Trees were irrigated identically in the spring and summer. A non-irrigation treatment was started on Hamlin and Valencia oranges in September and October, respectively, while controls continued to be irrigated following established irrigation practices. An additional non-irrigated treatment was started at the same time on the Valencias that consisted of a soil covering with a water barrier (Tyvek) to exclude rainfall. Stem water potential was monitored during the fall and winter to estimate differences in water stress among the treatments. Brix and organic acids increased in fruit from non-irrigated treatments when compared to fruit from irrigated trees. Results also demonstrate that reduced irrigation did not affect yield greatly. Amount of irrigation savings was determined for both cultivars that differ in maturity dates.
Crop Load and Canopy Temperature Affect Leaf Characteristics and Net Gas Exchange of `Spring' Navel Orange Trees
Authors: Otero Alvaro , Goni Carmen , Syvertsen* Jim
Published: February 2019

Six-year-old `Spring' navel [Citrus sinensis (L.). Osb.] orange trees were either totally defruited, 50% defruited or left fully cropped to study effects of fruit load on growth net gas exchange characteristics of mature leaves on seven selected clear days from Nov. 2001 through July 2002. Near harvest time, defruited trees had more shoot flushes, greater leaf dry wt per area (LDW/A) but lower net assimilation of CO2 (Ac) and stomatal conductance (gs) at midday than leaves on trees with fruit. Defruited trees had a higher ratio of internal to ambient CO2 (Ci/Ca) concentration in leaves implying internal limitations were dominant over stomatal limitation on Ac. Removal of half the crop increased individual fruit mass but reduced fruit color development. Half the trees were also shaded for four months prior to harvest with reflective 50% shade cloth to determine effects of lower leaf temperature (Tl) and leaf-to-air vapor pressure difference (D) on leaf responses. On selected clear days throughout the season, shade increased midday Ac and gs but decreased Ci/Ca compared to trees in the open implying that high mesophyll temperatures in sunlit leaves were more important than gs in limiting Ac. There were no effects of the shade treatment on canopy volume, yield or fruit size. Shaded fruit developed better external color but lower Brix than sun-exposed fruit. Thus, the presence of mature fruit maintained higher Ac than in leaves on defruited trees but high leaf temperatures and D reduced gs and Ac on warm days throughout the season.
C-Partitioning in Sweet Cherry (Prunus avium L) During Early Spring
Authors: Ayala Marlene , Lang* Greg
Published: February 2019

In deciduous fruit trees, some storage reserves accumulate during fall and are used for early spring growth. In sweet cherry (Prunus avium L), stored reserves are critical for early growth and there is a transition phase during which current photoassimilates become the primary source for support of reproductive and vegetative sinks. As little is known about this transition, an experiment using 4-year-old `Regina' sweet cherry on the semidwarfing rootstock, Gisela 6, was established. Using whole canopy exposure chambers, five trees were pulsed with high levels of 13CO2 on three different dates during fall (Sept.-Oct). At leaf drop, leaves, buds, wood, bark and roots were sampled for GCMS analysis of pre-winter storage reserves. The major storage organs (those which had the highest change in isotopic ratios) were roots and wood in the trunk and branches. During spring, newly developing organs (flowers, fruits and young leaves) were sampled weekly from bloom to stage III of fruit development for additional GCMS analysis. The stored 13C was mobilized and partitioned to flowers, fruits and young leaves from early spring until one week after fruit set. The highest 13C levels in growing sinks were observed between bloom and fruit set. The isotopic composition of new organs did not differ initially (3 May). During the three next sampling dates (10-24 May) reproductive organs had higher 13C levels compared to vegetative growth. The role of storage reserves, as a source of assimilates for early spring growth and their implications for crop development, will be discussed.
Antisense Inhibition of Sorbitol Synthesis Leads to Changes in the Activity of the Antioxidant System in Apple Leaves
Authors: Zhou* Rui , Cheng Lailiang , Dandekar Abhaya
Published: February 2019

Sorbitol is the primary photosynthetic end product in the leaves of many tree fruit species in the Rosaceae family, but its physiological role remains unclear. In this study, we determined the effect of decreased sorbitol synthesis on the antioxidant system that scavenges reactive oxygen species (ROS) in apple leaves. Sorbitol synthesis was decreased in apple leaves by antisense inhibition of aldose-6-phosphate reductase activity. Dehydroascorbate reductase (DHAR), glutathione reductase, and catalase (CAT) activities increased in the leaves of the transgenic plants with decreased sorbitol synthesis, whereas superoxide dismutase, ascorbate peroxidase, NADH dependent and NADPH dependent monodehydroascorbate reductase activity did not show significant changes. Ascorbate and glutathione concentrations were higher in leaves of the transgenic plants compared with the control. The effect of decreased sorbitol synthesis on the antioxidant enzyme activity was dependent on leaf developmental stages. Larger changes in the enzyme activities of CAT, DHAR, and GR were observed in the old leaves than in the young leaves. These results suggest that sorbitol may play a role in ROS scavenging in apple leaves.
Screening Landscape Roses for Salinity Tolerance
Authors: Hill* Samuel C. , McKenney Cynthia B.
Published: February 2019

Given the regularity of periods of drought in the southwestern U.S., concern over an ample supply of high quality water is always an issue. With a diminishing water supply, higher quality water will likely be diverted to higher priority uses; therefore, concern arises over the availability and quality of water for landscape use. This project was designed to screen representative cultivars from several of the major garden rose categories (China, Tea, Polyantha, Hybrid Tea, and Found Roses) for tolerance to saline irrigation water. Roses were placed in a completely randomized design with four replications in a container holding area. Salinity treatments were designed to be a 2:1 molar ratio of NaCl:CaCl2. The treatments consisted of 0, 6.25, 12.5, 25, and 50 mmol NaCl. The volume of solution applied to each treatment was adjusted at every irrigation event to meet ET and produce a 30% leaching-fraction. At the conclusion of the study, the China rose retained the best foliage while one of the hybrid tea roses maintained flowering throughout the study at all treatment levels. It appears that the roses with the smallest leaflets were able to tolerate salinity better than those with larger leaflets. Results of the tissue sample, leachate, spad and media analyses will also be presented.
Results from a Multi-year Evaluation Study of Epimedium Taxa
Authors: Rudy* Mark
Published: February 2019

The Chicago Botanic Garden (USDA Hardiness Zone 5b, AHS Plant Heat Zone 5) conducted an evaluation study of 40 taxa of Epimedium from 1995 to 2001. The goal of this project was to select superior taxa based on winter hardiness, ornamental merit, pest and disease resistance, and cultural adaptability. Three plants of each taxon were grown in a site that features a variety of light levels and diverse microclimates. Of the 40 taxa that began this trial, 33 survived to receive final ratings that ranged from excellent to poor. Although a wide variety of data was collected for each taxon, overall ratings were based on four criteria: flower coverage, health quality, overall habit quality and winter hardiness. Among the rated plants, three varieties stood apart from the others: Epimedium `Crimson', E. grandiflorum `Sonoyzki' and E. × versicolor `Neosulphureum'. One of the most significant characteristics that separated the best performers from the mediocre and poor performers was winter hardiness. Five taxa lost all three plants in the first winter of the trial and were not retested. Several other taxa had their overall ratings severely impacted by winter losses. In addition to winter hardiness, data on frost damage, nutrient limitation and rabbit damage were also collected. Epimedium habits varied from clumped to widespreading groundcovers. Of the 33 barrenwort taxa to receive final ratings, nine were determined to have significant potential use as groundcovers. Also, 12 taxa displayed highly ornamental, early-season foliage colors in shades of burgundy, bronze and red.
In Vitro Inhibitory Activity of Antimicrobial Peptides Cecropin, α-Thionin DB4, and γ-Thionin RsAFP1 Against Several Pathogens of Strawberry and Highbush Blueberry
Authors: Hammerschlag F.A.
Published: February 2019

As part of a program to develop transgenic highbush blueberry (Vaccinium corymbosum L.) and strawberry (Fragaria ×ananassa Duchesne) cultivars with increased levels of disease resistance, we have investigated the feasibility of introducing genes for the antimicrobial peptides cecropin B and MB39, α-thionin DB4 (DB4) and γ-thionin RsAFP1 (RsAFP1) by testing the effects of these peptides on several important pathogens of these two crop species. A thin-layer plate bioassay was conducted with these peptides and the pathogens Botrytis cinerea (Pers.ex. Fr.), Botryosphaeria dothidea (Mouq.ex. Fr.) Ces & de Not., Colletotrichum acutatum Simmonds, C. gloeosporioides (Penz.) Penz.et Sacc., C. fragariae Brooks, Monilinia vaccinii-corymbosi Reade (Honey), Phytophthora fragariae Hickman and Xanthomonas fragariae Kennedy and King. The minimum lethal concentration (μm) for cecropin ranged from 0.02 for X. fragariae strains 10 and 128 to 72.8 for C. gloeosporioides isolate Akp1. For DB4, the minimum inhibitory concentration (μm) ranged from 0.03 for X. fragariae strain 6 to 87.2 for B. cinerea isolate cc. For RsAFP1, the minimum inhibitory concentration (μm) ranged from 0.13 for X. fragariae strain 6 to 61.4 for M. vaccinii-corymbosi isolate 9423-x-45. These results indicate that introducing genes for either cecropin, DB4 or RsAFP1 into strawberry may be useful for controlling bacterial angular leaf spot disease caused by X. fragariae.
Fruit Quality Indices in Eight Nance [Byrsonima crassifolia (L.) H.B.K.] Selections
Authors: Medina-Torres Raúl , Salazar-García Samuel , Gómez-Aguilar José Roberto
Published: February 2019

Nance [Byrsonima crassifolia (L.) HBK.] is a tropical fruit cultivated along the coastal areas of Mexico. Nance consumption has increased due to its versatility, as it can be used as fresh fruit, refreshments, and alcoholic beverages and also for preparing fruit rolls, bottled drinks, jellies, syrup, ice cream, and cakes. However, the broad variation in fruit quality parameters, like juice acidity, total soluble solids, skin color, and size, seems to limit its use. Since fruit quality can be influenced by the parameter used, multivariate canonical discriminant analysis (CDA) was used to discriminate among nance selections. The objective of this study was to find the best quality indices using physical and chemical fruit characteristics from eight nance selections cultivated in the state of Nayarit, Mexico. Six physical and five chemical variables of fruit quality were studied to determine the relative contribution of each variable to the discrimination between nance selections. Two canonical discriminant functions (CDF1 and CDF2) explained >80% of the accumulated variation among nance selections. The total soluble solids (TSS) to titratable acidity (TA) ratio was dominant on the CDF1 (standardized canonical coefficient = 2.46), therefore, this ratio could be used as the best quality index to select nance fruit. The following TSS to TA values are proposed to classify the nance selections studied: a) 5.1 to 8 as sour fruit (Sour-small and Purple selections), b) 8.1 to 10 as sweet-sour fruit (Conical, Improved, Sweet-sour-1, Sweet-sour-2, and Sweet-sour-3 selections), and c) >10 as sweet fruit (Sangunga selection).
Ethephon Promotes Germination of Echinacea angustifolia and E. pallida in Darkness
Authors: Qu Luping , Wang Xiping , Yang Jinghua , Hood Eatherley , Scalzo Richard
Published: February 2019

Seeds from five lots each of Echinacea angustifolia DC and E. pallida (Nutt.) Nutt. were germinated in a growth chamber in light (40 μmol·m-2·s-1) or darkness at 25 °C for 16 to 20 days after soaking in 1 mm ethephon or water for 10 minutes or moist stratification at 4 - 6 °C for 2 weeks. Either light or ethephon promoted seed germination of E. angustifolia and E. pallida compared with darkness in nine of ten lots. Ethephon in the dark had similar or greater germination percentages than water with light. Ethephon with light improved germination in three of ten lots compared with ethephon in the dark. The effect of cold, moist stratification compared with darkness varied by seed lot. Five lots of E. purpurea (L.) Moench were tested, however, no treatment differences were measured. The finding that ethethon promoted E. angustifolia and E. pallida seed germination in darkness could be useful in the cultivation of these two species. Chemical name used: 2-chloroethylphosphonic acid (ethephon).
Far-red Light Alters Primocane Morphology of Red Raspberry
Authors: Dale Adam , Blom Theo J.
Published: February 2019

The objectives of the study were to determine whether raspberries responded to decreased red to far-red ratio and whether it was more effective at the beginning or end of the dark period. Increased proportions of far-red light increased the internode length when at the beginning of the dark period on the three raspberry cultivars `Lauren',`Reveille', and `Titan'. Cultivars varied in that internode length also increased in ambient daylength compared to short days in `Lauren' and `Reveille', but not in `Titan'. They also responded differently to photoperiod: `Titan' and `Lauren' grew under short days, whereas `Reveille' ceased growth.
Fruit Quality of Satsuma Mandarin Grown on the Northern Coast of the Gulf of Mexico
Authors: Ebel R.C. , Dozier W.A. , Hockema B. , Woods F.M. , Thomas R. , Wilkins B.S. , Nesbitt M. , McDaniel R.
Published: February 2019

This study was conducted to determine fruit quality of Satsuma mandarin Citrus unshiu, Marc. `Owari' grown on the northern coast of the Gulf of Mexico. Soluble solids increased linearly and titratable acidity decreased quadratically during October and November for the four sampling years. There was no significant interaction between sampling date and year. There was a significant year effect for titratable acidity, but not soluble solids or their ratio. A 10:1 soluble solids to titratable acidity ratio was observed on 10 Nov. Variation in fruit weight corresponded with cropload. Fruit weight increased during the sampling period due to an increase in fruit length since there was no change in width. Peel color was yellow-orange by 10 Nov., with many fruit still exhibiting patches of green color. Because of some green color present in the peel, the fruit would have to be degreened for successful marketing in U.S. retail chain stores.
Segregation of Scab Resistance in Three Apple Populations: Molecular Marker and Phenotypic Analyses
Authors: Shupert David , Smith Aaron P. , Janick Jules , Goldsbrough Peter B. , Hirst Peter M.
Published: February 2019

The codominant PCR marker AL07-SCAR closely linked to the Vf gene for scab resistance was used to genotype seedlings in three apple populations in which each parent (`GoldRush', `Enterprise', `Pristine', and CQR10T17) was resistant to apple scab. The marker was used to predict the genotype at the Vf locus. Each parent was heterozygous. In two populations (CQR10T17 × `GoldRush' and `Pristine' × `GoldRush') seedlings segregated 1:2:1 for fragments associated with VfVf:Vfvf:vfvf as predicted by Mendelian segregation. However, in another population (`GoldRush' × `Enterprise') the ratio was 1.5:1:1.5, suggesting some type of selection against heterozygotes. Fruiting seedlings were rated for the presence of fruit scab. No scab was observed on seedlings homozygous for the PCR marker linked to Vf, a small amount of scab was observed on one heterozygous seedling out of 35, and 22 of 26 seedlings that were homozygous recessive, had fruit scab.
Genetic Transformation of Garlic (Allium sativum L.) by Particle Bombardment
Authors: Robledo-Paz Alejandrina , Cabrera-Ponce José Luis , Villalobos-Arámbula Víctor Manuel , Herrera-Estrella Luis , Jofre-Garfias Alba Estela
Published: February 2019

Microprojectile bombardment was used to introduce DNA into embryogenic callus of garlic (Allium sativum L.) and produce stably transformed garlic plants. Embryogenic calluses, derived from garlic cultivar `GT96-1', were bombarded with plasmid DNA containing genes coding for hygromycin phosphotransferase and β-glucuronidase. Putatively transformed calluses were identified in the bombarded tissue after 4 months of selection on 20 mg·L-1 hygromycin B. The transgenic nature of the selected material was demonstrated by GUS histochemical assay and Southern blot hybridization analysis, and twenty transgenic plants were regenerated.
Reduced Cell Size and Cell Wall Components of Apple Softening before Ripening on the Tree
Authors: Choi Dong Geun , Yun Song Joong
Published: February 2019

The softening of fruit dramatically reduces its market value, especially when this occurs on the tree before ripening. The causes of fruit softening, before ripening, were examined through anatomical and phytochemical comparative analyses between normal fruit, fruit softened on the tree, and stored fruit. The typical morphological changes that occurred with the fruit included early senescence and decreased firmness. The decrease in firmness of softening fruit was due to smaller cell sizes but larger intercellular spaces. The water and free sugar content of the fruit flesh, as well as the weight and sugar content of the cell walls, were significantly lower in softening fruit. Conversely, uronic acid levels and β-galactosidase activity were slightly higher in the softening compared to normal fruit, but the latter was lower than in stored fruit. The results indicated that reduced cell size and cell wall mass were major changes occurring during fruit softening on the tree before ripening, suggesting a difference in the softening mechanisms in ripening and stored fruit.
Rootstock Effects on Growth and Quality of `Gala' Apples
Authors: Al-Hinai Yahya K. , Roper Teryl R.
Published: February 2019

The effect of rootstock on apple size is not clear due to inconsistent results of published studies. This study was conducted over 3 years at the Peninsular Agricultural Research Station near Sturgeon Bay, WI on 6-year-old `Gala' apple trees (Malus domestica Borkh) grafted on Malling 26 (M.26), Ottawa 3, M.9 Pajam 1, and Vineland (V)-605 rootstocks. Fruit diameter was measured weekly. Fruit weight and volume were estimated by a quadratic regression of weekly measurements. Fruit weight was positively correlated with fruit volume. Rootstock had no effect on fruit growth and final size even with the removal of crop load effects. Crop load was a highly significant covariate for fruit size, but canopy light interception and seed count were not. Trees on M.26 EMLA had slightly higher yield in 2000 but rootstock did not affect yield efficiency any year. Rootstock had no influence on fruit quality attributes during 2001; however, in 2002, fruit obtained from trees on Pajam-1 tended to be less firm. Generally, apple fruit size was influenced by crop load and other factors, but not by rootstock.
Garlic Productivity and Profitability as Affected by Seed Clove Size, Planting Density and Planting Method
Authors: Castellanos J.Z. , Vargas-Tapia P. , Ojodeagua J.L. , Hoyos G. , Alcantar-Gonzalez G. , Mendez F.S. , Alvarez-Sanchez E. , Gardea A.A.
Published: February 2019

Depending on clove size and plant stand, planting represents a considerable proportion of the total production costs in garlic cultivation. The objectives of this study were to analyze the influence of seed clove size, planting density and planting method on yield, bulb size and on the profitability of garlic for the fresh market, planted under fertigation. Two experiments were established to evaluate planting densities ranging from 300,000 to 500,000 plants/ha in the 1998-99 season, and 300,000 to 600,000 plants/ha during the 1999-2000 season. Two additional experiments were established to evaluate the effect of seed size in the range of 1.9 to 10 g/clove in 1998-99, and 1.9 to 17 g/clove in 1999-2000. Seed of Taiwan-type `Tacatzcuaro' garlic was used in all the experiments. A fifth experiment was established to compare mechanical vs. hand planting. The experimental design in all cases was a randomized complete block with four replicates. For the plant density study, yields varied from 23.5 to 29.9 t·ha-1 for the first year and from 32.1 to 39.7 t·ha-1 for the second season. For the seed clove size study, yields varied from 18.7 to 27.3 t·ha-1 for the first year and from 16.3 to 32.2 t·ha-1 for the second season. Yields and leaf area index (LAI) were directly related to planting density and clove size. Highest yields were attained with maximum studied densities in both seasons. However highest profitability was attained with planting densities of 420,000 plants/ha for the first year, as calculated from the regression equation and 300,000 plants/ha for the second year as there was no statistical difference (P > 0.05) with the two subsequent population treatments and the former has lower costs than the others. The biggest diameters of bulb were always attained with the lowest population densities. In regard to seed size, the highest yield was achieved with 7.5 g/clove for the first season and 13 g/clove for the second season, which also resulted in biggest bulb diameters and therefore in more valuable commercial classes. In accordance with the regression analysis, highest profits were obtained with clove sizes 3.6 to 6.5 g/clove, which yielded from 24 to 27 t·ha-1 for the first season and from 7 to 10 g/clove for the second season, for yields from 29 to 31 t·ha-1. In general, the largest-sized seeds produced lower profits than medium-sized seeds, even though yields were significantly higher. The best planting method for garlic, as evaluated in terms of yield, quality and profitability, was associated with good plant distribution in the field and planting the seed with the apex upwards, characteristics obtained in the hand-planted treatment.
Potted Gerbera Production in a Subirrigation System Using Low-concentration Nutrient Solutions
Authors: Zheng Youbin , Graham Thomas , Richard Stefan , Dixon Mike
Published: February 2019

To determine whether currently used commercial nutrient solution concentrations can be reduced during the final stage (last 4 to 5 weeks) of production of potted gerbera (Gerbera jamesonii `Shogun') under recirculating subirrigation conditions, plants were grown under one of four nutrient levels (10%, 25%, 50%, and 100% of full strength). Nutrient concentration levels did not affect leaf area, flower number and appearance, and plant total dry weight. There were no significant differences in the greenness (as measured by SPAD meter) of leaves from plants that received the 50% and 100% strength nutrient solutions. However, leaves from plants that received the 10% and 25% strength solution showed significantly less greenness than that of the plants that received 50% and 100% strength nutrient solutions. There were interveinal chlorosis symptoms on the younger leaves of some plants in the 10% and 25% strength nutrient treatments. It is suspected that this interveinal chlorosis was due to iron (Fe) deficiency caused by the increased substrate pH. It is concluded that the nutrient solution concentrations typically used for potted gerbera production in commercial greenhouses at the final stage (4 to 5 weeks) under recirculating subirrigation conditions, can be safely reduced by at least 50% without adversely affecting crop production. Nutrient salts accumulated in the top section of the growth substrate under all treatments levels; however, no phytotoxic effects were observed. No differences in water use (141 mL per plant per day) were observed amid the various nutrient levels. Fertilizer inputs were reduced in the 50%, 25%, and 10% treatments by 54%, 75%, and 90% respectively, relative to the 100% treatment. After 4 weeks under recirculating conditions, the qualities of the nutrient solutions were still within acceptable limits.
Light Intensity and Fertilizer Concentration: II. Optimal Fertilizer Solution Concentration for Species Differing in Light Requirement and Growth Rate
Authors: Nemali Krishna S. , van Iersel Marc W.
Published: February 2019

To evaluate the effects of increasing photosynthetic photon flux (PPF) on optimal fertilizer concentrations, we grew wax begonia (Begonia semperflorens-cultorum Hort.) and petunia (Petunia ×hybrida Hort. Vilm-Andr.) seedlings in a soilless growing medium without starter fertilizer under three PPF treatments (high, medium, and low corresponding to an average daily PPF of 23.2, 15.6, and 9.8 mol·m-2.d-1, respectively) and subirrigated with six fertilizer concentrations [electrical conductivity (EC) of 0.12, 0.65, 1.18, 1.71, 2.24, and 2.77 dS·m-1]. Compared to low PPF, shoot dry mass of wax begonia and petunia seedlings increased 2- and 3-fold, respectively, at high PPF. Fertilizer EC resulting in maximum shoot dry mass was the same (1.28 and 1.87 dS·m-1 for wax begonia and petunia, respectively) in the three PPF treatments. Shoot dry mass and leaf area of petunias decreased little at higher than optimal fertilizer EC in the three PPF treatments, while growth of begonia was inhibited at high fertilizer EC. The optimal fertilizer range, calculated as the lower and upper limits of fertilizer EC within which plant growth was not reduced by >10% as compared to the optimum EC was 0.65 to 1.71 dS·m-1 in wax begonia and 1.18 to >2.77 dS·m-1 for petunia. Compared to those grown at 1.18 dS·m-1, wax begonias grown at 1.71 dS·m-1 had similar dry mass, but were shorter in all three PPF treatments (average height reduction of 6.5%). In general, EC of the top layer of the growing medium was higher than that of the bottom layer of the growing medium, and this difference increased with increasing EC.
Light Transmission Through Colored Polyethylene Mulches Affects Weed Populations
Authors: Ngouajio Mathieu , Ernest Jeremy
Published: February 2019

Weed control is one of the benefits associated with the use of plastic mulches used for vegetable production. The mulches decrease light transmission and prevent development of most weed species. Plastics chemistry has developed films varying in their ability to reflect, absorb, and transmit light. Laboratory and field experiments were conducted to 1) measure light transmitted through colored mulches, 2) evaluate weed populations under each mulch type, and 3) determine if light transmission could be used as an indicator for weed populations in the field. The polyethylene mulches were black, gray, infrared transmitting brown (IRT-brown), IRT-green, white, and white-on-black (co-extruded white/black). On average, 1%, 2%, 17%, 26%, 42%, and 45% light in the 400 to 1100 nm range was transmitted through the black, white/black, gray, IRT-brown, IRT-green, and white mulches, respectively. In field experiments, density and dry biomass of weeds growing under the mulches were evaluated. The white mulch had the highest weed density with an average of 39.6 and 155.9 plants/m2 in 2001 and 2002, respectively. This was followed by the gray mulch, with 10.4 and 44.1 weed seedlings/m2 in 2001 and 2002, respectively. Weed density was <25 plants/m2 with the other mulches in both years. Weed infestation was correlated with average light transmission for white, black, white/black, and gray mulches. However, both light quantity and quality were necessary to predict weed infestations with the IRT mulches. Weed infestation under the IRT mulches was better estimated when only wave lengths in the photosynthetically active radiation range (PAR; 400 to 700 nm) were considered. Low weed pressure and high light transmission with the IRT mulches would make them appropriate for use in areas where both weed control and soil warming are important factors.
Blossom and Fruitlet Thinners Affect Crop Load, Fruit Weight, Seed Number, and Return Bloom of `Northern Spy' Apple
Authors: Nichols Douglas , Embree Charles , Cline John , Ju Hak-Yoon
Published: February 2019

To determine the effect of blossom and fruitlet thinners on crop load, fruit weight, seed development during the year of treatment, and the subsequent year effect on return bloom, fruit weight and yield, a field trial using the biennial apple cultivar `Northern Spy' (Malus × domestica Borkh.) was established. Treatments applied at full bloom included ATS (ammonium thiosulphate) [12% (w/v) nitrogen, 26% (w/v) S]; TD [15.9% (w/v) diacarboxylic acid, 5.5% (w/v) dimethylalkylamine salt (Endothal)] and SCY [57% (w/v) pelargonic acid (Scythe)]. At 18 days after full bloom (DAFB), oil treatments [98% (w/v) mineral oil (Superior “70” oil)] were applied with S [480 g·L-1 a.i. carbaryl (Sevin XLR)] and without as a means of increasing the efficacy of S. BA [19 g·L-1 a.i. 6-benzyladenine/1.9 g·L-1 a.i. gibberellins 4+7 (Accel)]; S; and/or SA [100% (w/w) 2-hydroxybenzoic acid (salicylic acid)], were also applied in a factorial arrangement on the same day. Fruit abscission was significantly increased the year of treatment with BA, S, BA + S, BA + SA, S + SA, BA + S + SA, oil, and S + oil. Average fruit weight was enhanced by S, BA + S, BA + SA, S + SA, BA + S + SA, and S + oil although in the latter treatment the crop load was very low. Only treatments that included BA reduced the number of fully developed seeds per fruit and seed number per trunk cross-sectional area (TCA) and increased return bloom. Defining the number of fully developed seeds per tree coupled with crop load is proposed as a predictor of return bloom in `Northern Spy'.
Relationships between Jasmonates and Chilling Injury in Mangosteens Are Affected by Spermine
Authors: Kondo Satoru , Jitratham Anan , Kittikorn Monrudee , Kanlayanarat Sirichai
Published: February 2019

Effects of low temperature and chilling injury (CI) on jasmonic acid (JA) and methyl jasmonate (MeJA) concentrations were investigated in mangosteens (Garcinia mangostana L.). JA concentrations in the skin of fruit stored at 7 °C increased significantly compared with that of those stored at 13 °C, but JA decreased with the occurrence of visible symptoms of CI. Neither an increase in JA nor CI was detected in pulp of fruit stored at 7 °C. JA concentrations in the skin of fruit treated with spermine (Spm) and stored at 7 °C also increased, but at a lesser extent than in untreated fruit. Thus, the response of JA to low temperatures appears to be limited to chill-susceptible parts of the fruit. The decrease of JA and the onset of CI was delayed in fruit treated with Spm kept at 7 °C compared with untreated control fruit. Exogenous application of n-propyl dihydrojasmonate, which is a jasmonic acid derivative, effectively decreased CI. These results suggest that low temperature-induced JA accumulation may play a protective role against CI. The application of jasmonates may increase chill-resistance in fruit.