Browsing by Author "Brian Whipker, Committee Co-Chair"

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    Adaptation of the PourThru Nutrient Extraction Procedures to Greenhouse Crop Production
    (2002-11-15) Cavins, Todd J.; John Dole, Committee Member; Ted Bilderback, Committee Co-Chair; Bill Fonteno, Committee Member; Keith Cassel, Committee Member; Brian Whipker, Committee Co-Chair; Dean Hesterberg, Committee Member
    The purpose of this research was to adapt the PourThru nutrient extraction technique, which is the displacement of the bulk solution from the production container without a destructive harvest, to commercial greenhouse crop production. PourThru is a quick and easy nutrient sampling technique that is not laboratory oriented and can help prevent costly nutritional problems for greenhouse crop producers. Additionally, time domain reflectometry (TDR) was evaluated as an experimental tool to measure substrate moisture content, which may affect PourThru extraction. Time domain reflectometry is quick, non-destructive and has potential for use in automation of moisture content determination in greenhouse production. Previous PourThru research had focused on techniques for use on large nursery containers (≈ 3800 cm3) versus the smaller floriculture containers (≈ 1500 cm3) and no exact calibration of PourThru nutrient values to saturated media extract (SME) values, the current standard for nutrient testing, had been completed. Therefore, studies were implemented to examine the relationship of PourThru to SME, evaluate irrigation systems and timing effect on PourThru results as well as develop recommended influent and leachate volumes to ensure an unadulterated sample. Calibration curves were developed between PourThru and SME values and r2 values ranged from 0.91 to 0.99 for linear relationships. Irrigation systems did affect electrical conductivity (EC) values and alternative interpretive standard values were developed dependent upon irrigation system. Timing of the PourThru was important to ensure adequate leachate was collected for sample analysis and the amount of influent affected EC values and the amount of leachate collected. The use of TDR was effective in small containers (980.6 and 2177.5 cm3); however, care should be taken to match probe size to container size to ensure representative sampling. The largest limitation to TDR use was the bulk density of the substrate being analyzed. Approximately a 50 to 75% underestimation occurred when substrate bulk densities were below 1.2 g.cm-3, but material specific calibration improved TDR accuracy to within 4%.
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    The Effects of Benzyladenine on Ornamental Crops
    (2008-12-04) Carey, Dennis John Jr; Brian Whipker, Committee Co-Chair; Mark Kistler, Committee Member; Wayne Buhler, Committee Co-Chair
    A synthetic cytokinin, benzyladenine (BA), has recently been released in the U.S. as Configure® (2% liquid solution) for use on ornamental plants. Experiments were conducted to determine the efficacy of BA on various ornamental crops and to determine the optimal concentrations. BA was trialed on petunias, succulents, Paeonia, Salvia ’Caradonna’, and Helleborus ×hybridus and resulted in an increase in shoot number. Succulents (Sempervivum, Echeveria, Jovibarba, Agave, and Aloe) were the most reactive. The ideal foliar spray concentrations of 200 to 400 mg•L-1 applied one time increased offset formation by two times in five Sempervivum cultivars and in Echeveria. The ideal foliar spray concentration of 1600 mg•L-1 applied one time increased offset formation by two times in one cultivar of Jovibarba. BA foliar sprays applied two times were ineffective on three Agave cultivars and three Aloe cultivars. Foliar sprays, drenches, fertigations, bulb soaks and plug dips in a range of concentrations, application numbers and timings were evaluated on an additional 48 annual and perennial species. Applications of BA had minor positive effects, no effects, or negative affects and the most promising commercial applications will be presented.