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  • Author or Editor: Larry Barnes x
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Seeds of Taxodium distichum (L.) Rich. were collected, germinated, and grown from native stands ranging from Mexico, Texas, Louisiana, Mississippi, and Alabama. Twenty-two provenance selections were planted in Summer 2004 in College Station, TX, in 36 replicated single-plant replications per block for a total of 792 trees. Below-average midsummer temperatures and above-average number of rainfall events were conducive to the development of a leaf blight associated with the presence of Cercosporidium sequoiae (Ellis and Everh.) W.A. Baker and Partridge. A survey conducted in Oct. 2007 rated differential defoliation responses among provenances. Selections of Taxodium distichum var. mexicanum (Gordon) from Mexico and south Texas showed defoliation rates from 89% to 96%, whereas T. distichum var. distichum from central Texas had defoliation ratings from 79% to 99%. With the exception of one family collected from the Sabinal River in Texas, the central Texas selections had similar defoliation compared with those from south Texas. Selections of T. distichum var. distichum and one selection of T. distichum var. imbricarium (Nutt.) Croom from southeastern regions (Alabama, Louisiana, Mississippi, and east Texas) showed greater tolerance to the presence of the leaf blight with 52% to 80% mean defoliation. A few individuals within these families exhibited little or no symptoms of the leaf blight. In general, those selections from high-rainfall, high-humidity areas had less defoliation associated with the presence of the leaf blight fungus, although defoliation was variable among provenances within all geographical regions. These results suggest that tolerance to defoliation from C. sequoiae could be included in selection criteria when choosing possible germplasm releases from Taxodium distichum.

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An experiment was initiated in June and Aug. 2004 to determine affects of ozonated fertilizer–injected water on plant growth of chrysanthemum (Chrysanthemum× morifoliumT. de Romatuelle `Covington'). Aliquots (20 L) of reverse osmosis water were amended with 0, 50, and 300 mg·L-1 N (21N–3.1P–5.8K) water-soluble fertilizer and exposed to ozone (O3) gas for 0, 30, 60, or 120 s at a flow rate of 300 mL/min. Containers were sealed and allowed to set for 15 min for O3 diffusion. Treated water was used to irrigate plants. Plants were in 10.2-cm pots and grown until floral initiation. Plants were harvested on 12 Aug. 2004 or 24 Nov. 2004. Growth index (height x canopy width × canopy width in a perpendicular direction/3), and shoot and root dry masses were determined. Interactions between fertility concentration and ozone exposure rates were nonsignificant (P≤ 0.05). Significant main effect differences occurred in growth index and shoot/root dry masses in response to fertilizer concentrations, but growth measures were not affected by ozone exposure. Peak ozone concentrations in fertilizer-injected irrigation water averaged 0.21 mg·L-1 O3 (120 s exposure at 300 mL·L-1) after 15 min diffusion time. At 20 min diffusion times, ozone levels dropped to 0 mg·L-1. No gross morphological differences or obvious necrosis typical of ozone damage on chrysanthemum occurred at any O3 exposure level. No observable nutritional deficiencies were noted. Vegetative growth of chrysanthemum was not directly injured by irrigation water that was exposed to ozone gas for 0 to 120 s at a 300 mL/min flow rate.

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