Resistance of six zoysiagrass cultivars to fall armyworm /
The use of resistant plant material is an economical, safe and effective way of controlling turf pests. Some resistant turfgrasses are resistant to insects via the production of plant secondary metabolites that posses antifeedant and / or biocidal properties. Structural strength, detergent fiber,...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728909031&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The use of resistant plant material is an economical, safe and effective way of controlling turf pests. Some resistant turfgrasses are resistant to insects via the production of plant secondary metabolites that posses antifeedant and / or biocidal properties. Structural strength, detergent fiber, lignin and silica in leaf sheaths have also been associated with insect resistance. Host plant nutrition can affect resistance to various pests. Many grasses are resistant to insects when they are modestly fertilized, but when fertilized heavily with nitrogen (N), resistance is broken. Better understanding of how management practices affect resistance of zoysiagrasses (Zoysia spp.) to fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is needed. The experiments conducted investigated the effects of date and N treatment on secondary plant metabolites, percent cell wall, percent hemicellulose, percent lignin, percent cellulose, percent silica and tensile strength and how they relate to FAW resistance. Experiments were conducted on six zoysiagrass cultivars planted on a fine, montmorillontic, thermic Vertic Albaqualfs at the Texas A&M University Field Lab located in College Station, TX. 'Cavalier', 'Emerald', 'Crowne', 'Palisades', 'El Toro' and 'Meyer' were replicated 4 times in a randomized split-plot design with N applied as (NH₄)₂SO₄ at 12.2 and 48.9 kg of N ha⁻¹ month⁻¹ during the growing season. Metabolite content was greatest in June and steadily declined throughout July and August. Metabolite production decreased as applied N increased. Peaks 3 and 9 were consistently associated with FAW mortality when analyzed by stepwise regression techniques. However, Peak 3 had an inverse relationship with resistance. Peak 9 was positively correlated with resistance, and occurred in moderate levels. Fiber analysis supported earlier findings that cell wall structural components are associated with insect resistance. Lignin, tensile strength and hemicellulose were positively correlated with FAW resistance. This study demonstrated that plants fertilized during the growing season with 48.9 kg of N ha⁻¹ month⁻¹ had greater percent cell wall and hemicellulose contents. Fall armyworm resistance in Zoysia spp. is due to several components acting together to defend the plant against FAW attack. Several secondary metabolites, lignin, hemicellulose and tensile strength were associated with FAW mortality. |
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| Item Description: | Vita. "Major Subject: Agronomy". |
| Physical Description: | ix, 53 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 49-52). |