Graduate Thesis Or Dissertation
 

Dinitroaniline-herbicide resistance in goosegrass (Eleusine indica) : ecophysiological aspects

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/m900nx60j

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  • Growth of individual goosegrass (Eleusine indica (L) Gaertn.) plants of three dinitroaniline-herbicide resistant (R) and three susceptible (S) biotypes from North Carolina, South Carolina, and Mississippi was analyzed in greenhouse experiments. Leaf area and biomass measurements, including root, shoot, above-ground, and total dry weights were similar among the biotypes studied. However, S-biotypes produced between 15% and 30% more reproductive biomass than R-biotypes. Slight differences in instantaneous leaf area ratio, net assimilation rate, and relative growth rate among biotypes were inconsistent and unrelated to dinitroaniline-herbicide sensitivity. Results confirmed that S-biotypes allocate more resources towards reproduction than R-biotypes, but overall growth is similar among biotypes. Responses of a R- and a S-biotype to competition were determined by planting both biotypes at various monoculture and mixture densities and proportions. In monoculture, reproductive output per plant decreased more with increasing density in the R-biotype than in the S-biotype, although no differences in above-ground biomass per plant were observed. Thus, the two biotypes differed in their partitioning of resources to seed production. In mixture, the R-biotype was more detrimentally affected by competition with the S-biotype than with itself. On the other hand, the S-biotype was more affected by intra-biotype competition than by competition with the R-biotype. Inter-biotype competition resulted in reduced tiller and inflorescence numbers, above-ground biomass, and, especially, reproductive output in the R-biotype. Results indicated that the R-biotype is less fit than the S-biotype. Several goosegrass populations from various counties from North Carolina and South Carolina were also tested for trifluralin sensitivity. Most populations were susceptible to the herbicide with GR₅₀ (herbicide rate required to reduce above-ground dry weight by 50%) values ranging from 0.33 to 1.82 ppm. Populations from Calhoun county (SC) had intermediate resistance to trifluralin (GR₅₀= 2.50-4.86 ppm). R-biotypes were not affected by the herbicide at the highest rate tested (4.86 ppm). Foliar isozyme patterns of selected populations were determined. The populations were homogeneous in isozyme activities, especially for malate dehydrogenase, peroxidase, and superoxide dismutase. Some variability in esterase was detected among populations but was unrelated to herbicide resistance. Cytological studies were conducted with five R- and three S-biotypes not exposed to dinitroaniline herbicides before examination with the electron microscope. Cell-wall malformations were found in some cells from two of the R-biotypes and in one of the S-biotypes. Malformations consisted of partially deposited cell walls and the inclusion of cell-wall material in the cytoplasm. Some of the affected cells also had abnormal, lobed nuclei and malformed mitochondria. Sgoosegrass treated with trifluralin [2,6- dinitro- N,N- dipropyl -4- (trifluoromethyl) benzenamide] exhibited typical cellular abnormalities, including binucleated cells.
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