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Title:The impact of allelopathic winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) residues on a vegetable cropping system
Author(s):Mwaja, Vasey Nyamu
Doctoral Committee Chair(s):Masiunas, John B.
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Agriculture, Agronomy
Agriculture, Plant Culture
Agriculture, Plant Pathology
Abstract:Experiments were conducted to determine the effect of allelopathic cover crops on a vegetable cropping system. A study was also undertaken to investigate the impact of cover crop residues on weed management. Winter rye (Secale cereale L. cv. Wheeler) and hairy vetch (Vicia villosa Roth cv. Oregon Crown) were interseeded in the fall. The following spring, cabbage (Brassica oleracea var. Capitata L. cv. Bravo), tomato (Lycopersicon esculentum Mill. cv. Market Pride) and snap bean (Phaseolus vulgaris L. cv. Mustang) were planted into cover crops that had been either desiccated with glyphosate (N-(phosphonomethyl)glycine) at 1.1 kg a.i ha$\sp{-1}$ (RT) or mowed and disked (Disked). Both methods left cover crop residue on the soil surface. A preplant incorporated application of trifluralin (2,6-dinitro-N,N--dipropyl-4-(trifluoromethyl)benzenanine) at 0.8 kg ha$\sp{-1}$ to bare ground was included as a conventional tillage (CT) control. Fifty percent of cover crop residues in RT persisted 12 wk in 1991, but only 6 wk in 1992, an unusually wet summer. In 1991, the decrease in residue mass during the growing season was linear. The greatest snap bean yields were in CT; total yields of cabbage and tomato were not affected by management system. However, early tomato yield was greater in the RT treatment than in the disked or CT production systems. In 1992, the greatest yields for cabbage and snap bean were in CT. Cabbage plants in the disked and CT treatments had significantly greater infestations of diamondback moth, imported cabbageworm, and cabbage looper than in RT plots. Rye and hairy vetch residues also inhibited weed growth. Redroot pigweed (Amaranthus retroflexus L.) accounted for 60 to 80% of the total weeds. Initial (2 wk) weed control in 1991, was poorest in the disked plots and was similar in RT and CT treatments. In 1992, all treatments were weedy. The RT treatment tended to have fewer grasses than the disked treatment.
A greenhouse experiment was conducted in 5, 10, and 20 mM NO$\sb3\sp-$ regimes to evaluate cover crop biomass production, rye shoot tissue phytotoxicity, and allelochemical content. Rye or polyculture of rye and hairy vetch treated with 20 mM nitrate solution produced more biomass than hairy vetch monocultures. Rye tissue phytotoxicity and the concentration of the allelochemicals, (2,4-dihydroxy-1,4(2H)-benzoxazin-3-one) (DIBOA) and 2(3H)-benzoxazoline (BOA) were affected by fertility regime. Cress (Lepidium sativum L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.) radicle elongation was inhibited by both the rye residues and their ether extracts. The ether extract concentrations causing 50% inhibition (I$\sb{50}$) of cress radicle elongation were between 125 and 276 $\mu$g ml$\sp{-1}$ for greenhouse-grown shoots and 60 and 138 $\mu$g ml$\sp{-1}$ for the field grown rye. The lowest levels of DIBOA and BOA were in the 20 mM NO$\sb3\sp-$ fertility regime. The concentration of DIBOA in the greenhouse-grown rye shoots ranged between 128 and 423 $\mu$g g$\sp{-1}$. It is likely that DIBOA and BOA from rye residues were inhibiting weeds in reduced tillage vegetable production.
Issue Date:1994
Type:Text
Language:English
URI:http://hdl.handle.net/2142/21455
Rights Information:Copyright 1994 Mwaja, Vasey Nyamu
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9416413
OCLC Identifier:(UMI)AAI9416413


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