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Marlene Ayala and Gregory Lang

, FL Flore, J.A. Layne, D.R. 1999 Photoassimilate production and distribution in cherry HortScience 34 1015 1019 Grossman, Y.L. DeJong, T.M. 1995 Maximum vegetative growth potential and seasonal partterns of resource dynamics during peach growth Ann

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Lauren M. Garcia Chance, Joseph P. Albano, Cindy M. Lee, Staci M. Wolfe, and Sarah A. White

. Plant Sci. 5:Article 548 Bertrand, I. Hinsinger, P. Jaillard, B. Arvieu, J.C. 1999 Dynamics of phosphorus in the rhizosphere of maize and rape grown on synthetic, phosphated calcite and goethite Plant Soil 211 111 119 Butcher, S.S. 1992 Chapter five

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Andrew J. Price, Craig S. Charron, Arnold M. Saxton, and Carl E. Sams

1 Department of Plant Sciences. 3 Current address: National Soil Dynamics Laboratory, USDA-ARS, Auburn, AL 36832. 2 Department of Animal Science. 4 To whom reprint requests should be addressed; e-mail carlsams@utk.edu .

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P.A. Jolliffe and W.C. Lin

Variation in shelf life of greenhouse-grown `Mustang' cucumber (Cucumis sativus L.) fruit was enhanced by preharvest experimental treatments of fruit thinning and fruit shading. Treatments also affected the dynamics of fruit elongation, fruit color at harvest, and chlorophyll fluorescence of the pericarp. Fruit color (grey level) at harvest, as measured by image analysis, had the highest simple (positive) correlation with shelf life. Rapid elongation and high photochemical quenching of fluorescence also characterized fruit having longer shelf life. The ability to predict cucumber yellowing is improved using a multiple regression approach, but prediction achieved by the best subset model is still too low to segregate commercially fruit having a short shelf life.

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Robert E. Lyons

An undergraduate “Service Course” generally presents principles of a particular discipline in an uncomplicated manner needing no prerequisites. The target audience is typically students majoring outside the service course department or undeclared majors. The primary motives behind service courses are recruitment from within the university, providing non-mjors with a broad appreciation for a discipline, and providing graduate students with classroom teaching/management experience. `The structure, dynamics, success, and adaptability of “Indoor Plants,” a Virginia Tech Horticulture service course enrolling approximately 400 students per year, will be discussed. Comparisons with other service courses will be made.

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D. Michael Glenn

The minirhizotron approach for studying the dynamics of root systems is gaining acceptance; however, problems have arisen in the analysis of data. The purposes of this study were to determine if analysis of variance (ANOVA) was appropriate for root count data, and to evaluate transformation procedures to utilize ANOVA. In peach, apple, and strawberry root count data, the variance of treatment means was positively correlated with the mean, violating assumptions of ANOVA. A transformation based on Taylor's power law as a first approximation, followed by a trial and error approach, developed transformations that reduced the correlation of variance and mean.

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C.J. Simon and N.F. Weeden

The ribosomal genes of the two crab apple (Malus) genotypes White Angel' and `Robusta 5' were characterized to determine the extent of between- and within-genotype heterogeneity. Initial investigations with a cloned sequence of soybean rDNA failed to detect some Malus intergenic spacer region fragments. An alternative probing method that used electrophoretically purified Malus rDNA was developed. Double-digests of total genomic DNA with combinations of 13 restriction endonucleases identified the positions of 35 restriction sites. Restriction site polymorphism was observed both between and within the crab apple genotypes. Ribosomal DNA from White Angel' was cloned in phage and plasmid vectors and mapped with 11 enzymes. The region of the spacer causing length heterogeneity was identified. These clones should be useful as genetic markers and for examining population dynamics and systematic of Malus and closely related taxa.

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Damon E. Abdi and R. Thomas Fernandez

Ornamental nurseries produce a large number of plants in a concentrated area, and aesthetics are a key component of the product. To produce crops in this manner, high inputs of water, nutrients, and pesticides are typically used. Container nursery production further increases the inputs, especially water, because container substrates are designed to quickly drain, and the most effective method of irrigating large numbers of plants in containers (up to a certain size) is the use of overhead irrigation. Because irrigation and pesticides are broadcast over the crop, and because the crop is limited to the container, a large proportion of water or pesticides may land on nontarget areas, creating runoff contaminant issues. Water is the primary means of pesticide movement in nursery production. This review discusses water and pesticide dynamics and management strategies to conserve water and reduce pesticide and water movement during container nursery production.

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Ed Peachey and Ray William

Altering the physical or chemical nature of the crop production environment through introduction of cover crops or other non-crop vegetation may amend the impact of various pests on vegetable crops. Current work is focused on the interaction of cereal cover crops and respective management systems with weed emergence and growth, white mold (Sclerotinia sclerotiorum) incidence, symphylan (Scutigerella immaculata) population dynamics, soil food-web structure, and crop yield in snap bean production systems. Research has demonstrated the potential of cover crop residues, tillage, and a single broadcast application of a postemergence herbicide to control summer annual weeds. Additionally, white mold incidence was significantly decreased by both reduced tillage conditions and flailed barley cover crop residues in one year of research. Two years of research indicate that symphylan density can be reduced by flailing spring-planted cereals before crop planting.

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Erin M. Silva, Bill B. Dean, and Larry Hiller

Successful pollination of onion (Allium cepa L.) flowers greatly depends on adequate nectar production. In order to understand the nectar production dynamics of onion flowers, nectar was collected at regular intervals during a 24-hour period. Hourly nectar volumes were compared to a variety of environmental conditions, including amount of solar radiation, relative humidity, temperature, wind speed, and evapotranspiration. Production patterns showed mid- to late-morning peaks and late evening peaks in nectar volume. Nectar appeared to be reabsorbed by the flowers during the afternoon and overnight hours. Individual flowers produced the highest amount of nectar several days after initially opening. Nectar production was significantly and inversely related to relative humidity while the effects of temperature, evapotranspiration, wind speed and solar radiation on nectar production were not significant in this study.