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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Using Day Neutral Cultivars and Low Tunnels to Extend the Strawberry Harvest Season in the Northeastern United States

Orde, Kaitlyn Marie 23 June 2018 (has links)
<p> Day-neutral strawberry cultivars have produced competitive yields and allowed for extended production in several recent experiments in the Upper Midwest and northeastern US, and the inclusion of small plastic-covered low tunnels has increased percent marketable yields and even total yields in some cases. However, low tunnel systems have not been evaluated for production conditions in New England, and cultivar evaluation is limited. The objectives of our experiments were to: (1) evaluate five different plastic films with diverse light-transmission profiles, as well as three mulch types (black plastic, white-on-black plastic, and bare ground) for low tunnel day-neutral strawberry production in New England, and (2) compare the performance of six standard day-neutral cultivars for their suitability at our location (&lsquo;Albion&rsquo;, &lsquo;Aromas&rsquo;, &lsquo;Monterey&rsquo;, &lsquo;Portola&rsquo;, &lsquo;San Andreas&rsquo;, and &lsquo;Seascape&rsquo;). We report that during the 2016 and 2017 growing seasons in Durham, New Hampshire, season-long cumulative marketable yields were comparable between plants under tunnels than open beds. However, yields were often increased under low tunnels during the late fall months compared with open bed production. Furthermore, unmarketable yields were significantly lower under low tunnels than open beds, increasing the percentage of marketable yield from &ap;70% on open beds, to &ap;80-85% under low tunnels (depending on low tunnel film and cultivar).Marketable yields were greater in 2017 than 2016, averaging 483.3 and 380.1 g/plant, respectively, and also higher on plastic mulched beds than unmulched beds, but did not differ between black and white plastic mulch. However, runner emergence was significantly reduced on white mulch and unmulched beds compared with black mulch, except for in 2016, when runner emergence on black plastic under low tunnels was comparable to white mulch and unmulched beds. </p><p> In the evaluation of multiple cultivars on black mulch only, season-long total marketable yields of &lsquo;Albion&rsquo;, &lsquo;Aromas&rsquo;, and &lsquo;Monterey&rsquo; were comparable, ranging from 355.0 to 389.1 g/plant. &lsquo;Portola&rsquo; (254.8 g/plant) and &lsquo;Seascape&rsquo; (285.3 g/plant) were the lowest yielding cultivars, significantly lower than &lsquo;Albion&rsquo; and &lsquo;Monterey&rsquo;. &lsquo;San Andreas&rsquo; was intermediate in yield (289.4 g/plant), lower than &lsquo;Albion&rsquo;, but comparable to other cultivars. Marketable fruit weight was also lower for &lsquo;Portola&rsquo; and &lsquo;Seascape&rsquo; than all other cultivars. Runner emergence was largely dictated by cultivar, and low tunnels significantly reduced runner emergence for &lsquo;Aromas&rsquo;, &lsquo;Monterey&rsquo;, and &lsquo;San Andreas&rsquo;, and in one of two years, for &lsquo;Albion&rsquo; on black plastic mulch. At a plant density of 13,068 plants/acre and an average &lsquo;Albion&rsquo; yield of 12,937 lbs/acre, we estimate net revenue would range from $22,517 ($2.90/lb) to $43,215 ($4.50/lb) per acre under open field conditions.</p><p>
2

Effects of Pre-Sowing Incubation within a Pyramid on Germination and Seedling Growth of Phaseolus vulgaris L.

Motloch, Lauren Nicole 25 October 2017 (has links)
<p>Food is crucial for all life on the planet, however food security is a problem in many parts of the world (Van Straaten, 2006). In the last decade the number of undernourished grew to 1.02 billion (FAO, 2009). Shapouri et al. (2010) estimates by 2020 food insecurity will reach 500 million in SSA. In a world with limited resources, the only solution to meet food demand is by maximizing yield per unit of land (Van Straaten, 2006). Large-scale intensive farming is widely practiced in the US as a solution to this growing problem (Fyfe et al., 2006). Current food production practices are driven by mass production, which is highlighted by large inputs including pesticides, fertilizers, and irrigation. Although these techniques have revolutionized agriculture and helped combat world hunger, ill effects have been reported such as soil degradation and loss of biodiversity (Tilman et al., 2002). Alternative techniques can be introduced which increase plant production and are environmentally friendly, less costly, and less intensive (Theodoro & Leonardos, 2006). Two of these methods are magnetic fields and radiation (Aladjadjiyan, 2012). Magnetic fields were confirmed to affect plant growth, germination, metabolism, and vigor (Celik et al., 2009; Zuniga et al., 2016). Literature suggests pyramidal shapes harness the magnetic field of the earth to generate para magnetism within their structure (Van Doorne, 2013). Although pyramids have produced documented improvements in plant growth and germination (Kumar et al., 2010), the use of pyramids to incubate seeds before planting has not been tested. The purpose of this research was to describe the impacts of pre-sowing incubation within a pyramid on germination characteristics, seedling growth, seed desiccation, and soil condition, as well as describe any relationships existing between independent and dependent variables. Both wooden and copper pyramids were used, and seeds were incubated for periods of 5, 10, 35, and 45 days. A total of 1,800 seeds were tested. Data were analyzed in SPSS using one-way ANOVA?s at p<.05 significance level. Pyramids negatively affected germination frequency, percentage, time, and rate, but positively affected uniformity (synchrony, uncertainty, variation of germination time). Conclusions indicate longer incubation periods are beneficial for germination and uniformity, while shorter incubation periods increased vegetative growth. Copper pyramids exceled over wooden pyramids when examining seedling growth. Copper pyramids paired with longer incubation periods saw the highest increase in seed weight. The highest average soil temperature was recorded in the wooden pyramid, and soil pH remained unchanged.

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