دانلود پایان نامه بیماری شناسی گیاهی pdf
در این صفحه دو پایان نامه در رشته بیماری شناسی گیاهی قرار داده شده است. فایل PDF این پایان نامه ها را می توانید از قسمت "فایل ها برای دانلود" در پایین همین صفحه دریافت نمایید.
افزایش پتانسیل کنترل بیولوژیکی نماتدهای بیماریزای حشره زا در برابر خشک شدن و اشعه UV
Enhancing the Biological Control Potential of Entomopathogenic Nematodes Protection from Desiccation and UV Radiation
Entomopathogenic nematodes (EPNs) are obligate parasites of insects. EPNs have a broad host range, are easily mass reared, and kill insects within 48 hours. EPNs are safe for vertebrates, plants, and non-target organism. On the other hand, EPNs have disadvantages that make them less effective against foliar insect pest because they are sensitive to desiccation, ultraviolet (UV) radiation and high temperatures. The goal of this research was to improve the efficacy of aboveground application EPNs by protecting them against desiccation and UV radiation. The first objective was to determine efficacy of the desiccation protectant Barricade gel in extending the viability of EPNs. The second objective was to evaluate the effect of UV chemical protectants on EPNs viability. The third objective was to demonstrate enhanced insect control with EPNs protected from UV radiation and desiccation.
Barricade® is a proprietary fire-protection product that prevents desiccation. Barricade® gel toxicity to Steinername feltiae and mealworm (Tenebrio molitor) was determined in laboratory experiments. Subsequently, the effect of Barricade® gel on IJ infectivity was determined at different (0, 1, 1.5, 2, 3, and 4%) concentration. Barricade® gel was not toxic to mealworm larvae nor the IJ of S. feltiae. IJ survival was enhanced by Barricade® gel and Barricade® gel prevented desiccation of IJs allowing for greater IJ infection and mealworm larvae mortality. In an excised leaf experiment, Barricade® application enhanced IJ infection of the mealworm larvae over time compared to application in water alone.
EPNs and mealworm larvae were exposed to UV radiation protectant chemicals P-amino benzoic acid (PABA) and octyl methoxycinnamate (OMC), Congo red, titanium dioxide, and zinc oxide were not toxic to mealworm larvae and EPNs. PABA, OMC, Congo red, titanium dioxide, and zinc oxide protected IJ from exposure to UV light for 0, 4, 8 and 12 hrs. After 48 hrs exposure, PABA afforded the greatest protection to EPN compared to other chemicals. OMC provided the second greatest protection to EPN compared to other chemicals.
The UV protectants PABA and OMC were individually combined with Barricade® fire gel and IJs were added. The IJs were exposed to full spectrum UV light in the laboratory for up to 12 hrs. The subsequent number of dead mealworm larvae was greatest in the combination treatments of OMC+Barricade and PABA+Barricade. These treatments afforded the greatest protection to IJs from UV radiation and desiccation in a filter paper experiment and a choy sum (Brassica chinensis var. parachinensis) leaf assay.
The survival of IJ can be enhanced when applied with a desiccant protectant such as Barricade and a chemical such as PABA or OMC to protect against UV radiation. The protection afforded to the IJ by these chemicals allows for greater infection and mortality of target insect pests. The formulation of IJs with desiccant and UV radiation protection will allow the greater use of EPN for the management of foliar insect pests.
ارزیابی سیستم پوششی چاودار برای کنترل علف های هرز و تحمل سیب زمینی شیرین به ایندازیفلام
Evaluation of a Rye Cover-Crop System for Weed Control and Sweetpotato Tolerance to Indaziflam
Sweetpotato is North Carolina’s third most valuable crop in terms of production value. Palmer amaranth (Amaranthus palmeri) is the most common and troublesome weed in North Carolina sweetpotato production fields. Palmer amaranth can cause high yield loss and a reduction in storage root quality. Despite the high value of sweetpotato, growers have few options in controlling weeds. Most herbicides registered for use in sweetpotato are not effective on Palmer amaranth. Furthermore, biotypes of Palmer amaranth in NC have been reported to have developed resistance to ALS- EPSPS-, and PPO-inhibiting herbicides. Thus, the objectives of this dissertation were to (1) evaluate the utility of a reduced-tillage, high residue rye mulch production system for weed control in sweetpotato and (2) evaluate a new herbicide mode of action for use in sweepotato.
Studies were conducted in NC to determine the effect of high-residue rye [Secale cereal (L.)] cover crop or no rye cover crop on soil health, and growth and storage root yield of sweetpotato [Ipomoea batatas (L.) Lam.] cultivars having upright (NC04-0531 or NC15-650) or prostrate (‘Covington’ or ‘Bayou Bell’) vining characteristics. Sweetpotato canopy width expanded quicker in the conventional tillage system than the reduced-tillage system. The conventional-tillage system resulted in 17% more marketable roots, however, no differences were observed in total marketable root weight between systems. ‘Covington’ and ‘NC15-650’ had greater marketable yield than ‘NC04-0531’ but less marketable yield than ‘Bayou Bell’. Concurrent studies were conducted in NC to determine herbicide program efficacy in reduced-tillage and conventional sweetpotato production systems. Treatments included two production systems (conventional, or reduced-tillage with rye cover crop). Herbicide program treatments included flumioxazin, flumioxazin tank mixed with clomazone, fomesafen, indaziflam, or bicyclopyrone pre-transplant, with or without clomazone after transplanting, and S-metolachlor with or without linuron at 10 to 14 DAP. Nontreated weed-free (hand-weeded) and weedy checks were included for comparison. Herbicide program treatments including linuron POST had the greatest broadleaf weed control in the reduced-tillage system. In the conventional tillage system, all herbicide programs except for bicyclopyrone followed by Smetolachlor and fomesafen treatments without linuron had > 85% broadleaf weed control at 8 wk after planting. In the reduced-tillage system in 2019 only flumioxazin followed by clomazone and S-metolachlor tank mixed with linuron had similar total yield as the weed-free check. In 2020, all herbicide programs resulted in similar total yield, however, the conventional tillage system had greater total yield than the reduced-tillage system.