Eastern black nightshade is one of the problematic weeds in vegetables and soybeans in the Midwest. It is representative of a rapidly growing complex of broadleaf weeds where herbicide resistance would be expected to occur. Eastern black nightshade calli lines that are resistant and susceptible to acifluorfen were maintained on the medium without the herbicide. After two years, these lines were tested for tolerance to acifluorfen and paraquat. Tolerance to acifluorfen was maintained in the previously selected lines. The lines were also cross tolerant to paraquat. Plants were regenerated from these calli lines and grown in the greenhouse. 14C-acifluorfen and 14C-paraquat uptake, translocation, and metabolism were studied.
Experiments determined the effectiveness of the bipyridinium herbicides paraquat and diquat and of the diphenyl ether herbicide lactofen to desiccate onion (Allium cepa L.) shoots without affecting bulb quality and storage life. Paraquat, applied once, desiccated 80% of onion shoots within 3 days. Diquat desiccated ≈ 60% of onion shoots within 10 days of treatment. Lactofen caused slight necrosis but did not adequately desiccate onion shoots. Diquat and paraquat reduced sprouting of `Red Wethersfield' more than of `White Portugal'. Chemical names used: 6,7-dihydrodipyrido[l,2 2',1'-c] pyrazinediium ion (diquat); (±)2-ethoxy-l-methyl-2-oxoethy1 5-[2chloro-4-(trifluoromethyl)phenoxyl] -2-nitrobenzoate (lactofen); 1,1'-dimethyl-4,4'-bipyridinium ion (paraquat).
The Cooperative Extension Service (CES) is undergoing a period of self-evaluation (Gerber, 1985) and change (USDA Extension Service, 1988). As part of on-going discussions on the future of the CES at the Univ. of Illinois, a survey of the academic staff in the Dept. of Horticulture was conducted. The survey quantified the reaction of horticultural academic staff to recommendations taken from a federal study on the future of extension (USDA Economic Committee on Organization and Policy, 1987) and statements solicited from the Dept. of Horticulture Extension Committee. Recipients of the survey were asked to state their level of agreement or disagreement with the statements on a scale of 1 to 5 (1 = strongly disagree, 2 = disagree, 3 = no opinion, 4 = agree, and 5 = strongly agree).
In the past few years, leaf trichomes of tomato (Lycopersicon esculentum) and related wild species have received considerable attention due to their potential role in insect resistance. However, the last complete characterization of all 7 trichome types was by Luckwill in 1943, before the advent of scanning electron microscopy (SEM). Since that time, the taxonomic designations of the genus have been modified, expanding from 6 species to 9. The purpose of this work was to use SEM to observe and record trichome types from the presently accepted Lycopersicon species, and determin etheir species specific distribution. Studies have shown variation within trichome type due to number of cells per trichome, and base and surface characteristics.
The objective of this study was to investigate the chromosomal and genotypic variation in regenerated plants of Solarium and Lycopersicon. Calli of Lycopersicon peruvianum genotypes PI199380, PI126345, PI251301, and LA1373, along with Solanum ptycanthum were transferred onto media consisting of MS salts with Gamborg vitamins. The shoots formed were rooted in vitro and transferred to greenhouse soil. Actively growing root tips were harvested and pretreated, fixed, hydrolyses and stained. Pollen mother cells were fixed in propionic alcohol solution and stained with aceto-carmine. The number of chromosomes were counted. The greatest variation was in Solanum ptycanthum with chromosome numbers ranging from 18 to 60 (2n=24). Progeny analysis for 12 somaclones of Solarium ptycanthum was done by selfing for two generations. Morphology, shoot height, and weight were determined in each generation. The amount of variation differed among the somaclonal lines.
Friable callus of Solanum ptycanthum and L. peruvianum PI199380 clone 149 were subcultured on liquid Murashige and Skoog salts and Gamborg Vitamin medium with 2,4-D (1mg/l) until a fine suspension of cells was obtained. The suspension cultured cells were then plated on selection medium. Twenty-five acifluorfen-tolerant cell lines of Solanum ptycanthum and fourteen tolerant Lycopersicon peruvianum cell lines were obtained by a stepwise increase in concentration of acifluorfen. Acifluorfen-tolerant cell lines were transferred on to regeneration media with the herbicide. Shoot regeneration differed depending on the cell line and acifluorfen concentration, ranging from 0 to 37 plants per calli. As acifluorfen concentration increased in the regeneration media, the number of shoots and shoot height decreased. There was a wide range of variation in shoot morphology, which depended on the cell line.
Black polyethylene mulch and weed control strategies were evaluated for potential use by small acreage herb producers. In both 1988 and 1989, the mulch greatly increased fresh and dry weight yields of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.). Parsley (Petroselinum crispum Nym.) yield did not respond to the mulch. Preplant application of napropamide provided weed control for 2 weeks, but was subsequently not effective on a heavy infestation of purslane (Portulaca oleracea L.). Hand-hoed and glyphosate-treated plots (both with and without plastic) produced equivalent yields. Chemical names used: N, N -diethyl-2(1-napthalenoxy)-propanamide (napropamide); N- (phosphonomethyl) glycine (glyphosate).
Greenhouse hydroponics and field experiments were conducted to determine how nitrogen (N) fertilizer treatments affect tomato (Lycopersicon esculentum Mill.) growth, yield, and partitioning of N in an effort to develop more sustainable fertilization strategies. In a hydroponics study, after 4 weeks in nitrate treatments, shoot dry weight was five times greater at 10.0 than at 0.2 mm nitrate. An exponential growth model was strongly correlated with tomato root growth at all but 0.2 mm nitrate and shoot growth in 10 mm nitrate. Root dry weight was only 15% of shoot biomass. In field studies with different population densities and N rates, height in the 4.2 plants/m2 was similar, but shoot weight was less than in the 3.2 plants/m2. At 12 weeks after planting, shoot fresh weight averaged 3.59 and 2.67 kg/plant in treatments with 3.2 and 4.2 plants/m2, respectively. In 1998, final tomato yield did not respond to N rate. In 1999, there was a substantial increase in fruit yield when plants were fertilized with 168 kg·ha-1 N but little change in yield with additional N. Nitrogen content of the leaves and the portion of N from applied fertilizer decreased as the plants grew, and as N was remobilized for fruit production. Both studies indicate that decreasing N as a way to reduce N loss to the environment would also reduce tomato growth.