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Weiguang Yi and Hazel Y. Wetzstein

Herbs have been long known to provide health-promoting benefits and are demonstrated to have antioxidant, anti-inflammatory, antibacterial, analgesic, and antitumor activities. This study evaluated the effects of drying conditions and extraction protocols on the biochemical activity of three culinary and medicinal herbs: rosemary (Rosmarinus officinalis), motherwort (Leonurus cardiaca), and peppermint (Mentha piperita). Leaf tissues were dried by sun, oven-dried at 40 °C, or oven-dried at 70 °C and extracted using 80% methanol or 80% ethanol. Total polyphenol (TPP) using the Folin-Ciocalteu reagent method and antioxidant capacity using the Trolox-equivalent antioxidant capacity (TEAC) assay were determined. Both drying and extraction conditions significantly impacted TPP content and TEAC in the three herb species. Sun-dried or 40 °C oven-dried herbs exhibited significantly higher TPP content and TEAC capacity than fresh samples, suggesting low-temperature drying may be a good postharvest means to store medicinal/culinary herbs. Exposure to 70 °C oven-drying caused significant antioxidant loss. In addition, the current study showed that with fresh tissue, 80% ethanol extraction had significantly higher TPP and TEAC than 80% methanol extraction for all three herbs, yet for dried herbs, the efficacy of ethanol/methanol extraction varied with different drying treatments.

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Weiguang Yi, S. Edward Law, and Hazel Y. Wetzstein

In almond [Prunis dulcis (Mill.) D.A. Webb.], fungicide sprays are required to prevent blossom blight, which can infect open flowers. Numerous studies have reported detrimental effects of agrochemical sprays on pollination, fruit set, and yield in tree fruit crops. However, effects of fungicides on pollen germination and growth in almond are little known, particularly those from recently developed active ingredients. In this study we evaluated the effects of commercial formulations of 10 fungicides on pollen germination and tube growth in almond using in vitro assays. Assays conducted at 1/100 recommended field rates (RFR) were effective in delineating differences in almond pollen sensitivity to different fungicides. Captan and azoxystrobin were the most inhibitory, with germination percentages of less than 1% of the no-fungicide control. Germination was not significantly affected by propiconazole and benomyl. Intermediate inhibitory effects on pollen germination were observed with ziram, cyprodinil, maneb, thiophanate-methyl, iprodione, and myclobutanil. In contrast to germination, tube growth was less affected by the presence of fungicide. In pollen that germinated, tube elongation was the same as in controls in five of 10 of the fungicides evaluated. Nonetheless, azoxystrobin and captan reduced tube elongation by ≈90%. Some fungicide treatments also influenced tube morphology. In the absence of field evaluation studies, in vitro germination data may provide insight on how specific chemicals may impact pollination processes and further guide in vivo studies, particularly in the case of new chemical formulations.

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Hazel Y. Wetzstein, Weiguang Yi, Justin A. Porter, and Nadav Ravid

Pomegranate trees (Punica granatum) produce large numbers of both hermaphroditic (bisexual) flowers that produce fruit and functionally male flowers that characteristically abort. Excessive production of male flowers can result in decreased yields resulting from their inability to set fruit. Within hermaphroditic flowers, sex expression appears to follow a spectrum ranging from those exhibiting strong to weak pistil development. Unknown is the scope that flower quality plays in influencing fruit production. A description of floral characteristics and how they vary with flowers of different sizes and positions is lacking in pomegranate and was the focus of this study. Furthermore, the effects of flower size and position on fruit set and fruit size were evaluated. This study documents that flower size characteristics and ovule development can be quite variable and are related to flower type and position. Single and terminal flowers within a cluster were larger than lateral flowers. In addition, lateral flowers exhibited a high frequency of flowers with poor ovule development sufficient to negatively impact fruiting in that flower type. Ovule numbers per flower were significantly influenced by flower size with more ovules in larger flowers. Pollination studies verified significantly higher fruit set and fruit weight, and larger commercial size distributions were obtained with larger vs. smaller flowers. Thus, flower quality is an important issue in pomegranate. Cultural and environmental factors that influence flower size and vigor may have a direct consequence on fruit production and yield.