1,721,042 research outputs found
Winter Hardiness and Spring Regrowth of Four Varieties of Stevia rebaudiana (Bertoni) in Eastern North Carolina
No full textStevia (Stevia rebaudiana) is attracting attention in the United States in response to consumer demand for healthier low-calorie sweeteners. Farmers are looking at stevia as a valuable alternative crop to add to their rotations not only for its high value but because it is perennial and can be repeatedly harvested reducing annual establishment costs. S&W Seed Company is testing stevia varieties across the southeastern United States at locations in North and South Carolina, Georgia, and Alabama. This study evaluated four stevia varieties grown at two locations near Nashville and Roseboro in North Carolina. S&W is focused on developing cultivars suited to the climate of the southeastern United States. Research was conducted for eight months in fields near Nashville and Roseboro North Carolina to assess winter survival, spring regrowth, and leaf-to-stem ratio of four top performing varieties in plots contracted by S&W with local farmers. All four varieties overwintered without significant winter kill and spring regrowth began from crowns in April and May. Weed interference in the Nashville location negatively affected percentage of regrowth in the spring. In Roseboro with lower weed pressure, regrowth occurred a month earlier with increases of 43% for SW-1005, 50% for SW-2267, and 114% for SW-2647. SW-2427 had no difference in percentage of survival between locations. Plants in Roseboro had greater mean plant heights and leaves per stem count. Stevia can be grown as an alternative perennial crop in coastal Carolina although there was significant winter die back and spring regrowth was slow.MAL
Does Position in Cantaloupe (Cucumis melo L.) Fruit Affect Seed Quality?
No full textEffects of the location of seed development inside cantaloupe (Cucumis melo L.) fruit on seed germination percentage and vigor was compared for two Western Shipper cantaloupe cultivars (‘Ropey King’ and ‘Expedition’). Mean time to germination (MTG), as (NiTi )/ (Ni) where Ni is the number of newly germinated seeds at time Ti after imbibition was calculated as a measure of seed vigor. Fruit was grown in Woodland, CA, in a randomized complete block design, consisting of 4 blocks (i.e., replicates). Melons were harvested at the full slip stage of maturity and were measured and sliced into six equal sections (blossom end top, blossom end bottom, middle top, middle bottom, stem end top, and stem end bottom). Harvested seed was equally divided for germination testing without drying immediately after harvest (no seed storage, NSS), and after 6 months of seed storage (6MSS) of dried seeds. 6MSS was stored in a cold temperature-controlled (3.33°C, 35% relative humidity) refrigerator in sealed containers for six months, so moisture content did not fluctuate. Both cultivars showed improved germination percentage after 6MSS. Moreover, the 6MSS of both cultivars resulted in significantly higher (P ≤ 0.05) germination percentages in the stem end and middle sections of both cultivars. In contrast, MTG increased after 6MSS compared to NSS possibly because of differences in hydration. However, after 6MSS seeds from the stem end and middle fruit sections of both cultivars germinated faster (P ≤ 0.05) compared to seed from the blossom end indicating the most vigorous seeds developed in those sections.MAL
Efficacy of Organic Fungicides for Control of Powdery Mildew, Downy Mildew, and Plectosporium in Pumpkins
No full textIncreased agritourism in the state of Virginia has led to an increase in the pumpkin planting acreage for pick-your-own operations across the commonwealth. Virginia pumpkin producers face yield losses from numerous sources, including several fungal diseases. The objective of this research was to compare the efficacy of certified organic fungicides against a conventional fungicide program for the control of powdery mildew, downy mildew, and plectosporium. Cultivar Warty Goblin pumpkins were grown in Rockville, Virginia during the 2016 crop season. Five different treatments (water, Kaligreen, Nordox, Regalia, and Bravo +Quintec/Proline) were assessed for their control of powdery mildew, downy mildew, and plectosporium. Disease observations and treatments were made weekly from August 12 – September 15. Disease ratings for powdery mildew showed that conventional fungicides provided the greatest control, with organic products Kaligreen and Nordox providing next-best control, statistically equivalent in some analyses. Regalia did not provide significantly better disease control than untreated water controls. Plectosporium disease severity was reduced the most in plots receiving conventional fungicides, with Nordox being almost as effective. Kaligreen provided no control of plectosporium. Regalia provided modest control, which in some analyses was significantly better than the untreated control. Downy mildew pressure was extremely limited, and no significant differences in disease incidence were seen among the treatments. In conclusion, several of the tested organic materials proved to be statistically as effective as the conventional fungicides in controlling both powdery mildew and plectosporium, although conventional fungicides provided numerically superior control for all diseases.MAL
Quantitative Real-time PCR Analysis of Tobacco mosaic virus in Individual Flue-cured Tobacco Seed
No full textThe Tobacco mosaic virus (TMV) has infected tobacco plants since the late 1800’s, causing detrimental yield and economic losses in tobacco. TMV is classified as a seed borne virus because the virus infects tobacco seed as a contaminant on the seed coat surface. The purpose of this study is to investigate seed-borne transmission of Tobacco mosaic virus (TMV) by examining the infestation route of tobacco seeds. Four different crosses were performed using K326 flue-cured variety: 1) self-fertilized, TMV infected, 2) self-fertilized, non-TMV infected, 3) TMV maternal infected, and 4) TMV paternal infected. Tobacco seeds were collected from three individual pods for each cross. Total RNA was extracted from 100 individual seeds per pod, and synthesized into cDNA for analysis. A quantitative real-time PCR (qRT-PCR) assay was developed to analyze TMV concentrations within individual tobacco seeds. qRT-PCR was adopted over other traditional viral detection methods for its capability of generating fast quantitative results in real time. Results revealed distinct TMV concentration patterns and data suggests uneven distribution of TMV within individual seed pods. These results show evidence of maternal but not paternal seed-borne transmission of TMV. Furthermore, dissection of individual seed reveals that the majority of TMV found in the seed is located within the seed coat and not the embryo. These findings may be useful in identifying the TMV infection route of entry in emerging tobacco seedlings.MAL
LabField™ as a Tool for Predicting Field Emergence of Diverse Melon Genotypes
No full textMany vegetables have specific climatic requirements with relatively narrow temperature and moisture optima for best establishment and production. Global climate change threatens food crop production in some areas because of shifts in temperature and moisture distribution. Identifying germplasm with greater environmental adaptability will help sustain global vegetable production. LabFieldTM tables were developed to test seed germination and plant growth in soil maintained at constant temperature or along a gradient of temperatures in a laboratory. The LabFieldTM eliminates using multiple growth chambers to test the same broad range of environments. In this study, we compared field emergence of five melon (Cucumis melo L.) with emergence of the same genotypes on a LabFieldTM table and using standardized Association of Official Seed Analysts germination tests on paper towels. The objectives were to identify genetic variation in germination performance and to test LabFieldTM as a tool for accurately predicting field emergence.Published versionInvited 30 minute webinar that was part of an international online seed conference hosted by the Institute of Vegetable Crops, Angers France. There were roughly 220 participants from countries in Western Europe. The Zoom presentation was recorded and posted on the French experimentation website: www6.angers-nantes.inra.fr/irhs_eng/Research/SEEDYes, abstract only (Peer reviewed?
The Potential for Green Fluorescent Protein as a Screening Tool in the Production of Haploid Potato Plants
No full textA hybrid between a highly regenerative diploid clone (BARD 1-3) of Solanum phureja and haploid inducer IVP 101 was transformed with Agrobacterium tumefaciens strain 4404 containing plasmid pHB2892 with genes for green florescent protein (GFP) and kanamycin resistance. Hemizygous primary transformants (To) were produced from three leaf discs: 17 diploid plants from one leaf disc, three and nine tetraploids from the other two leaf discs. GFP expression was observed qualitatively under fluorescence microscopes and quantitatively with a GFP meter. Anther culture of tetraploids produced 29 plants, none with high levels of GFP. Segregation ratios for tetraploid T1 seedlings fit models for single duplex insertions (35 transgenic: 1 non) or double simplex insertions (15 transgenic: 1 non). Diploid T1 seedlings segregated for deleterious traits: dwarfed size and curled leaves, as well as the GFP transgene. Similar segregation patterns in diploid families implied that all diploids may have been from the same transformation event. The cumulative segregation showed the dwarfed and curled plants fit a single recessive gene ratio (3 normal: 1 mutant), and GFP fit a double-copy insertion ratio (15 transgenic: 1 non). There was substantial GFP silencing evidenced by the loss of expression in plants that had originally been selected for high GFP. However, six selections were found to be free of deleterious traits, consistently high expressers of GFP, and producers of stainable pollen with less 2n than IVP 101.Master of Scienc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Visualizing and Assessing Seed Germination, A simple experiment for K-12 teachers
No full textMost crops are grown from seed. The seed industry in the US is a major agricultural industry employing tens of thousands of people. The value of agricultural seeds sold in the US, Mexico, and Canada each year is worth billions of dollars. Seed production for propagation is a major industry in California, Iowa, Minnesota, Oregon, Washington, and Idaho. The exercise described below is designed to give students a hands-on experience with seeds that can be conducted in a classroom or at home. The experiment can be used to discuss related issues like food security, global warming, human health, genetic engineering etc.Published versionthis is one of many exercises designed to help teachers education students about plant science and it is posted online for K-12 teachers at the agronomy4me websit
Virginia Report: Seed Research Activities in Virginia for 2021
No full textUnpublished versionSeminar presented at the NY Ag Experiment Station in Geneva NY, to Cornell faculty, graduate students, USDA employees and members of USDA Research Project W-416
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