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K.H.S. Peiris and S.J. Kays

Centella asiatica, the Asiatic pennywort, is an herbaceous perennial indigenous to the southeastern United States. In some Asian countries, it is valued as an important vegetable and is widely cultivated. In addition, it is considered an important medicinal herb due primarily to the pentacyclic phytochemical, asiaticoside, which effectively treats a variety of skin diseases. Information on the botany, photochemistry, medicinal, nutritional value, and cultivation of the crop is reviewed. This species may warrant preliminary field and consumer acceptance tests as a speciality vegetable in the United States.

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Geoffrey Weaver and Marc W. van Iersel

directly. Φ PSII is a unitless measure of the efficiency with which absorbed light is used to drive photochemistry in the light-adapted state of PSII. The dark-adapted value of the quantum efficiency of PSII (F v /F m ) is an indicator of maximum potential

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Joseph P. Albano

complexone were used for determining spectra of the free-ligand: 2006 acquisition used in marigold production study (2006 source) and 2009 acquisition used in photochemistry studies (2009 source). For comparison, as described for FeEDDS and free EDDS ligand

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Joseph P. Albano and William B. Miller

Irradiating a ferric ethylenediaminetetraacetic acid (FeEDTA)-containing commercially available soluble fertilizer with ultraviolet (UV) and blue radiation from high intensity discharge (HID) lamps caused the photooxidation of the FeEDTA complex, resulting in the loss of 98% of soluble iron. The loss of soluble iron coincided with the development of a precipitate that was mostly composed of iron. The effects of using an irradiated FeEDTA-containing fertilizer solution on plant growth and nutrition under commercial conditions were studied. Application of the irradiated fertilizer solutions to greenhouse grown tomato plants (Lycopersicon esculentum) resulted in lower levels of iron (6%) and zinc (9%), and higher levels of manganese (8%) and copper (25%) in leaf tissue compared to control plants that received a nonirradiated fertilizer solution. Leaf macronutrient levels (phosphorous, potassium, calcium, and magnesium), leaf dry weight, leaf number, and plant height was not affected by application of the irradiated fertilizer solution.

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Joseph P. Albano and William B. Miller

Irradiation of, ferric ethylenediaminetetraacetic acid (FeEDTA, iron chelate)-containing commercial fertilizer solutions by fluorescent plus incandescent lamps resulted in the loss of both FeEDTA and soluble iron (Fe), and the formation of a yellow-tan precipitate that was mostly composed of Fe. The ratio of soluble Fe:manganese (Mn) was altered due to FeEDTA photodegradation from 2:1 in the nonirradiated solutions to 1:4 in the irradiated solutions, respectively. Storing fertilizer solutions in containers that were impervious to light prevented FeEDTA photodegradation.

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Joseph P. Albano and William B. Miller

Irradiation of FeDTPA-containing nutrient solutions by a fluorescent plus incandescent light source resulted in the loss of both Fe-chelate and soluble Fe, the formation of a precipitate that was composed mostly of Fe, and a rise in pH. The rate of Fe-chelate photodegradation in solution increased with irradiance intensity and with solution temperature under irradiation, but irradiance had the greater effect. Fe-chelates absorb in the blue and UV regions of the spectrum. Removal of these wavelengths with a spectral filter eliminated photodegradation. Chemical name used: ferric diethylenetriaminepentaacetic acid (FeDTPA).

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M. Carmen González-Mas, M. José Llosa, Antonio Quijano, and M. Angeles Forner-Giner

). The coefficient for photochemical quenching, q P , which represents the fraction of open PSII reaction centers, was calculated as (F m ′ – F t )/(F m ′-F o ′) ( Schreiber et al., 1989 ). The quantum efficiency of PSII photochemistry, Φ PSII , closely

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Shuyang Zhen and Marc W. van Iersel

., 2005 ). The importance of acclimation to different light levels for the efficiency with which plants use supplemental light for photochemistry has not been studied. Currently, supplemental lighting in greenhouses is typically controlled by a timer or

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Chenping Xu and Beiquan Mou

Youssef (2010) found that composted manure increased chlorophyll content in cucumber leaves. There are very limited reports on the photochemistry of photosystem II as affected by compost amendment. In this study, composted cotton burr had no effect while

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Haiyan Zhao, Haiying Liang, Yibing Chu, Congcong Sun, Ning Wei, Mengnan Yang, and Caixia Zheng

decrease occurred. Fig. 3. Effects of NaCl on ( A ) maximum quantum yield of photosystem II (PSII) photochemistry ( F v /F m ), ( B ) actual quantum yield of PSII photochemistry (Φ PSII ), ( C ) nonphotochemical quenching coefficient (q N ), and ( D