Evaluating Silicon Foliar Sprays as a Strategy to Improve Postproduction Performance of Potted Basil (Ocimum basilicum L.)

The objective of the study was to evaluate foliar silicon (Si) applications for effects on the growth and performance of container-grown basil during production and resistance to postproduction wilt in retail. Basil (Ocimum basilicum ‘Genovese’ L.) seedling plugs were transplanted into 10-cm diameter plastic containers with peat-based substrate and grown for 42 d in a polycarbonate greenhouse. Plants were irrigated with fertilizer solution consisting of a 17.0 nitrogen (N)-1.3 phosphorus-14.1 potassium water-soluble fertilizer dissolved in tap water at 150 mg∙L-1 N. Foliar sprays containing sodium silicate at 0, 50, 100, 200, and 400 mg∙L-1 Si mixed with deionized water were applied every 7 d. Spray solutions also contained a non-ionic surfactant at 0. 3 mL∙L-1, and a 100% deionized water spray treatment was included as a no-surfactant control. Data collection consisted of leaf SPAD chlorophyll content, shoot height, shoot fresh and dry mass, and Si concentration in dried shoot tissue for four replicates per treatment. Four remaining replicates per treatment continued for a simulated retail phase, during which all replicate containers were irrigated to saturation with clear (no fertilizer) water and placed an indoor environment. Plants were checked twice daily for visible wilt, and number of days until wilting was recorded. To minimize the variability in daily evapotranspiration caused by fluctuations in the retail environment and temperature, days to wilt was standardized by dividing the total water loss per replicate determined using gravimetric methods by the average daily water loss from evaporation pans. The 0 mg∙L-1 Si and no-surfactant control treatments were combined for greater statistical power as there were no differences in their effects. Single degree-of-freedom contrasts were used to compare the effects of each Si treatment to the non-silicon control. Leaf SPAD chlorophyll content was greater for each Si treatment compared to the control. Shoot dry mass was also greater when Si was applied at 400 mg∙L-1, but there was no effect on shoot fresh mass or height. Shoot Si content increased with spray concentration, ranging from 466 to 882 μg∙g-1 of dry tissue for 0 and 400 mg∙L-1 Si treatments, respectively. Foliar sprays of 200 and 400 mg∙L-1 Si increased the number of days until wilting by 2.2 and 2.5 d, respectively. Based on these results, foliar Si sprays applied during production may be a practical and effective strategy for growers to increase resistance to wilting during retail for basil, with minimal effects on plant growth and quality

A Tunable Snapshot Imaging Spectrometer

A tunable snapshot imaging spectrometer has been demonstrated. A liquid crystal spatial light modulator (LC SLM) has been integrated into a computed tomographic imaging spectrometer (CTIS) to achieve tunability. The LC SLM allows for rapid, programmable, and non-mechanical alteration of its phase profile by the application of appropriate voltages to its transparent electrodes.The goal of this dissertation is twofold: (1) to integrate a liquid crystal spatial light modulator into a CTIS instrument and characterize its performance as a tunable CTIS disperser, and (2) to implement tunability by analyzing different CTIS configurations.The theoretical model of CTIS operation, calibration, reconstruction, and disperser design are covered in detail. The cross talk of the LC SLM forces the use of a feedback design algorithm rather than designing the desired phase profile a priori in the computer. The modifications to the current polychromatic linear inversion technique for use with the LC SLM in feedback are presented. The result of the modifications is the successful integration of a reprogrammable (i.e. tunable) disperser for the CTIS instrument.The implementation of tunability is explored by analyzing the spectral resolution of a reconstructed point source for different disperser configurations. A method for experimentally determining the CTIS spectral resolution is presented

Tim Tebow

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Silicon Foliar Spray and Substrate Drench Effects on Plant Growth, Morphology, and Resistance to Wilting with Container-Grown Edible Species

The objective of this study was to evaluate silicon (Si) foliar spray and substrate drench effects on plant growth and morphology for container-grown edible crops during greenhouse production, as well as resistance to plant wilting during post-production. In the first greenhouse experiment, basil received Si foliar sprays at 0, 50, 100, 200, and 400 mg∙L–1 Si. In the second greenhouse experiment, Si was applied as either a foliar spray (500 mg∙L–1 Si) or substrate drench (100 mg∙L–1 Si) with six edible crop species. Supplemental Si increased shoot Si levels but had minimal effects on plant growth and morphology, except for parsley, which resulted in distorted growth and phytotoxicity. In the first experiment, 200 and 400 mg∙L–1 Si foliar sprays increased plant resistance to wilt by 2.2 and 2.5 d, respectively; however, this was not observed in the second experiment. All species accumulated Si with the control (no Si) treatments, indicating trace amounts of Si were taken up from the substrate, fertilizer, spray surfactant, and irrigation water. Only cucumber was classified as a Si “accumulator” with a high capacity for Si uptake. Results emphasize the need to conduct preliminary trials with supplemental Si to avoid issues of phytotoxicity