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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.
181

No-Till Tomato Production

Booker, Bradley L 01 November 2009 (has links)
Tillage increases erosion rates and diminishes the quality of soils but has traditionally been a way to manage weeds and prepare a seedbed. No-till vegetable production can ameliorate the ill-effects of tillage in an economically effective way but has not been studied much in California. The objective of this thesis was to determine the viability of no-till vegetable cropping on the Central Coast of California. Tomatoes were grown in no-till and conventionally tilled treatments. Total yield, fruit weight, weed emergence, soil bulk density, soil aggregate stability, and soil organic carbon content were measured and compared. Yields and soil tests in both treatments were similar while weed emergence in the tilled plots was significantly higher than in no-till plots. The results may help vegetable producers determine how to make vegetable production on the Central Coast more sustainable.
182

Analysis of a mixed cereal of legumes that processes similar nutritional characteristics to a cereal product of local consumption and its economic feasibility

Garcia, Willy Ivan Anzaldo 01 January 2001 (has links)
In this analysis, we plan on developing vegetable mixes with high nutritional qualities and instant fuel consumption. These are to be used as a nutritional supplement in the feeding of children from 6 months of age. Initially, I selected the raw material, due to its high protein content and low cost (soy, tarhui, Cuban corn, rice, wheat, barley). They formed mixes with nutritional characteristics similar to the control for reference (15.5% of protein, 419 kcal of energy). From these formulas, different tests of completed production of mixtures, going so far as to obtain eight mixes with good nutritional and organoleptic characteristics. The eight mixes and the control for reference were subjected to sensory analysis tests (sensory quality test and acceptability and preference test), Of these mixes, 4 were selected (WA1, WA2, WA5 and the control for reference WA7) such as finished women mixtures. The same groups were subjected to a bromatologic analysis and biological tests with animals from the laboratory. Finally, the study of industrial viability of a small processing plant of instant vegetable mixtures was conducted.
183

INTEGRATING COVER CROPS AND HERBICIDES FOR HORSEWEED [<em>Conyza canadensis</em> (L.) Cronq.] MANAGEMENT PRIOR TO SOYBEAN [<em>Glycine max</em> (L.) Merr.]

Sherman, Austin 01 January 2019 (has links)
Horseweed (Conyza canadensis (L.) Cronq.) is prevalent in Kentucky and can be difficult to control. Research has shown multiple weed control methods to be more sustainable than relying on chemical control alone, so the use of multiple methods for horseweed management was examined in this study. The main objective was to determine best practice(s) to reduce horseweed prior to soybean [Glycine max (L.) Merr.]. Treatments included: fall-planted cover crop [CC; cereal rye (Secale cereale L.) or none], fall-applied herbicide (saflufenacil or none), and spring-applied herbicides (dicamba, 2,4-D ester, or none). We hypothesized horseweed densities would be reduced the most where all factors were combined. Saflufenacil suppressed horseweed densities from application through March, when densities increased due to a lack of competition from other winter weeds. Spring herbicides decreased horseweed densities until soybeans reached V1 in 2017, but in 2018 lost efficacy after CC termination. CC alone resulted in the longest horseweed suppression. The combination of spring herbicides and CC usually reduced horseweed densities to near zero between the CC termination and soybean planting. However, some low densities seen soon after soybean planting could be problematic. Further research must be conducted to determine the best integrated horseweed management system until soybean canopy closure.
184

Precision Drought Stress in Orchards: Rootstock Evaluation, Trunk Hydration and Canopy Temperature

Scott, Lance V. 01 May 2017 (has links)
In many areas, over half of all diverted water is used for irrigation. Tree fruit crops use a lot of water, but water productivity can be increased using properly-timed precision water stress. In addition to water conservation, increases in water productivity arise from better fruit quality, increased storage life and reductions in pruning and maintenance. One major hurdle to applying precision water stress in orchards is the lack of a reliable, automated method of determining tree water status. However, the influence of physiological characteristics such as rootstock vigor on water productivity are also important. Selecting the most appropriate rootstocks and accurately determining the water status of orchard trees can increase water productivity. Research has shown that some rootstocks can more effectively extract water from soil. In this research, the response to water stress of three different Gisela tart cherry dwarfing rootstocks was compared using a weighing lysimeter system. Gisela 12 and Gisela 3 rootstocks recovered from drought stress more quickly and had higher trunk diameter growth rates than drought-stressed Gisela 5 rootstocks. Two potential methods of determining tree water status were also evaluated. Trunk hydration was measured using electromagnetic sensors and canopy temperature changes were detected using infrared radiometry. Electromagnetic techniques, including time domain reflectometry, can be used to determine the water content of wood. Until recently, the cost of this technology has inhibited its widespread use, but new affordable commercial electromagnetic soil moisture sensors have created renewed interest in this technique. In this research five different types of electromagnetic soil moisture sensors were inserted into the trunks of fruit trees and were monitored over two growing seasons. Maximizing exposure of waveguides to the sapwood increased the response of these sensors to changes in stem water potential. Infrared measurements of canopy temperature have successfully been used with field crops. However, the heterogeneity of orchard canopies makes this technique more difficult in orchards. Here, the efficacy of aiming radiometers at single trees versus at entire orchards was compared over multiple growing seasons. Neither single tree measurements nor whole orchard techniques produced a sufficiently robust signal to recommend them for general use.
185

Untangling the Economic and Social Impediments to Producer Adoption of Organic Wheat

Ralph-Quarnstrom, Donya L. 01 May 2019 (has links)
Consumer demand for organic products has shown double-digit growth in recent years encouraging the development of a wider range of goods (Greene, 2017). Americans with an annual household income under $30,000 actively purchase organic foods at nearly the same rate as households with over $75,000 in annual incomes, 42% versus 49% (Greene et al., 2017). Previous research observed the adoption of organic farming practices on a combination of different grains, fruits and vegetables, meat, and dairy products from across the globe. However, this is the first study to examine the adoption of organic wheat in the Western U.S. By addressing the recent challenges and by discussing the current demands of the U.S. consumers, future research and decision making (including policy updates and grant opportunities) may become more impactful. Through an online survey of western wheat growers, we look at potential patterns in farm characteristics, grower characteristics, concerns about growing organic products, factors discouraging adoption production technology, and the use of resources on the likelihood of becoming an organic grower. A total of 82 valid surveys were collected. Findings suggest operators of smaller farms are more likely to be organic growers. Wheat growers willing to take risks to increase profits and those who considered financing availability a hurdle to adoption were also more likely to use organic methods. Interestingly, operator gender and years of experience had no impact on adoption. Using resources such as university research, consultants, etc. decrease the likelihood of becoming an organic producer.
186

Temperature and Atmospheric Humidity as Factors Influencing Seed Setting in Alfalfa

Clark, Lealand A. 01 May 1931 (has links)
For many years seed growers have thought that definite relationships existed between seed production and the weather. When this subject is approached there is little unity of opinion, even among neighboring seed growers. This lack of unity would indicate that growers generally are aware of some cause which affects seed setting, but they are not certain that any particular condition of the weather is the chief contributing factor. Scientific writers1 on the subject are also confident that weather is probably one of the major factors influencing seed production.
187

Effects of Phosphorus on No-Till, Minimum-Till, and Conventional Till Irrigated Field Corn

McKay, John A. 01 May 1987 (has links)
This investigation involved three tillage treatments, fall plowed (conventional) (moldboard IS-centimeter depth), fall chiseled (ripped) (25-centimeter depth), and no-tillage (zero tillage) replicated four times on an established alfalfa field. Rye was planted in the fall and harvested prior to planting the corn. Soil samples contained an average of 5.9 ppm phosphorus in the 0-30 centimeter soil layer, indicating the need for additional phosphorus. Within each tillage treatment, six rows received 11 kilograms/hectare phosphorus with the seed and 34 kilograms/hectare phosphorus side-dressed. Six rows received 45 kilograms/hectare phosphorus side-dressed, and four rows received 0 phosphorus. All 16 rows received 64 kilograms/hectare of nitrogen to ensure it was a non-limiting factor. Yields were significantly higher in every tillage plot that received phosphorus compared to the 0 kilograms phosphorus/hectare treatments in the plots. There was a trend of higher yields with the treatments of 11 kilograms/hectare + 34 kilograms/hectare side-dressed compared to the 45 kilograms/ hectare phosphorus side-dressed treatments. However, these were not significantly higher. The no-till plots yielded higher than the ripped or plowed in each tillage treatment. The differences between the no-till and ripped plots were not significant. However, the no-till plots yielded significantly higher than the plowed plot. The no-till 11 kilograms phosphorus + 34 kilograms phosphorus plots averaged 3.1 Megegrams/hectare higher silage yield than the plowed 11 kilograms phosphorus + 34 kilograms phosphorus plots and 2. 5 Megegrams/hectare higher in the 45 kilograms phosphorus side -dressed plots. Phosphorus uptake was measured by leaf sampling and found to be significantly higher in the no-till plots compared to the ripped and plowed plots. TON and protein were also determined, however, no significant differences existed between any tillage treatments. The rye was intended to be cut prior to planting for forage use in a dairy or cattle feeding program. Although the average dry weight was only 598 kilograms/hectare due mainly to late planting, this method has great economical potential.
188

Inheritance of Chaff Color, Head Shape, and Grain Texture in Wheat

Tingey, Delmar C. 01 May 1924 (has links)
The data presented in this thesis are the results obtained from a study of the F2 and F3 generations from a cross between the wheat varieties, Dicklow and Hard Federation. Toward the end of the summer of 1922 this problem was assigned to me by Professor George Stewart. The plants then growing in the field were in the F2 generation, the cross having been made in 1920 by Professor Stewart. The chief purpose of the cross was to improve the grain quality of spring-irrigated wheat by the application of Mendelian principles in such a way as to combine the high-yielding power of Dicklow with the good grain quality of Hard Federation. Before the data obtained in the cross are presented the history, description, and distribution of each parent will be given. This is followed by a brief review of the literature concerning inheritance of three characters in the wheat plant, viz., (1) chaff color, (2) head shape, and (3) grain texture.
189

Herbicide, Salinity, and Flooding Tolerance of Foxtail Barley (Hordeum jubatum L.) and Desirable Pasture Grasses

Israelsen, Karl R. 01 December 2009 (has links)
Research trials performed in the greenhouse compared the tolerance and response of Hordeum jubatum and desirable pasture grass species to herbicides, salinity, and flooding. Desirable grass species used in this study included: `Fawn' tall fescue (Festuca arundinaceae), `Garrison' creeping foxtail (Alopecurus arundinaceus), `Palaton' reed canarygrass (Phalaris arundinacea), `Climax' timothy (Phleum pratense), `Alkar' tall wheatgrass (Thinopyrum ponticum), `Potomac' orchardgrass (Dactylis glomerata), and `Mustang' altai wildrye (Leymus angustus). Tolerance to herbicides, salinity, and flooding varied significantly among grass species. Herbicide tolerance was tested using four herbicides at five rates each. The herbicides used were imazapic (Plateau), propoxycarbazone (Olympus), sulfosulfuron (Outrider), and flucarbazone (Everest) at rates of 0, 10, 25, 50, 100, and 200 g ha-1. Foxtail barley was least tolerant of sulfosulfuron and propoxycarbazone. Tall fescue, creeping foxtail, and reed canarygrass were susceptible to all the herbicides tested. Timothy and foxtail barley were moderately tolerant while tall wheatgrass exhibited the greatest tolerance to flucarbazone. Orchardgrass was most tolerant to propoxycarbazone. Salinity tolerance was determined by exposing grasses to increasing electrical conductivity (EC) over time. Reed canarygrass and timothy were most susceptible to salinity. Orchardgrass, creeping foxtail, and tall fescue were moderately tolerant of salinity. Foxtail barley, altai wildrye, and tall wheatgrass exhibited the highest tolerances to salinity, and continued to persist at the highest EC levels tested. Flooding tolerance was determined by flooding grasses in 18 cm of water for 2, 4, 6, and 8 weeks. Grasses that were able to extend above the water surface survived, whereas plants that failed to extend beyond the water surface experienced higher mortality rates.
190

A Study of the Seasonal History of Alfalfa Flowers as Related to Seed Production

Carlson, John W. 01 May 1927 (has links)
A few researches have been concerned with the structure and pollination of alfalfa flowers. Others have considered the biological problems concerned in the pollination and fecundation of the flowers. In none of these studies, however, has an attempt been made to follow carefully the alfalfa flowers through various stages of development. Nor has any effort been made to determine what effect the condition and duration of these stages may have upon the resulting seed crop The work that follows is a study of the changes through which the alfalfa flowers pass during the season while functioning as organs of seed production. Special effort has been made to study the condition and duration of the stages as they are related to the subsequent seed crop.

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