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  • Author or Editor: J. A. Taylor x
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In 1992, a cultivar trial was initiated in Columbus, Ohio to evaluate differences in establishment and long-term performance of cultivars of tall fescue (Festuca arundinacea), creeping red fescue (F. rubra), chewings fescue (F. rubra ssp. fallax), hard fescue (F. brevipila), kentucky bluegrass (Poa pratensis), rough bluegrass (P. trivialis), and perennial ryegrass (Lolium perenne) under low maintenance conditions in a shaded environment. Fertilizer and supplemental irrigation were applied until 1994 to establish the grasses, after which no supplemental irrigation, or pesticides were applied and fertilizer rates were reduced to 48.8 kg·ha-1 (1 lb/1000 ft2) of N per year. Percentage cover and overall quality data were collected in 2000 and compared with data collected in 1994. Initial establishment success does not appear to be a good predictor of long-term success of a cultivar in a shaded environment. There was some variability in cultivar performance under shade within a given turfgrass species. The tall fescue cultivars, as a group, had the highest overall quality and percentage cover under shade, followed by the fine fescues, kentucky bluegrass, rough bluegrass, and perennial ryegrass cultivars.

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Water is pervasively involved in the life cycle of seeds. Water in the environment, either as a vapor or liquid, directly affects seed moisture status. This article is devoted to the study of seed moisture status in postharvest events. Two topics are discussed: imbibitional chilling injury and upgrading of primed seeds. Imbibitional chilling injury is a physiological disorder that occurs in large-seeded legumes as well as other important agronomic seeds. Imbibitional chilling injury has been shown to reduce the survival rate of seedlings. Surviving seedlings have less emergence force per seedling and require a longer period to generate maximum force. Rapid hydration has been shown to induce injury at a particular seed moisture level. Methods of regulating the hydration rate were explored to alleviate chilling injury in snap beans (Phaseolus vulgaris L.) Plant breeding lines with the semihard seed characteristic delayed the onset of imbibition when the initial moisture level was low (8%). Coating seeds with polymeric films to complement the permeable testa retarded the imbibition rates. Both approaches alleviated chilling injury and improved seedling establishment under stressful conditions. Seed priming is a technique for elevation of seed moisture content before sowing. Primed seeds generally emerge more quickly than nonprimed seeds, especially under stressful environmental conditions. An additional merit of this technique is that it gives access to seeds with elevated moisture content. Various approaches may be employed to condition seeds after priming, but before redesiccation. Discarding the low-density fractions of primed tomato and lettuce seeds improved the percentage of germination compared with nonprimed seeds. Physiological mechanisms are presented to explain the association of density with seed viability in lettuce (Lactuca sativa L.).

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Substantial quantities of water and nutrients are required for the production of high value nursery and greenhouse crops. As water quality criteria are strengthened locally and nationally, horticultural enterprises will have to meet stricter limits on nutrients in discharge water. This study examined the efficacy of an established vegetated surface-flow constructed wetland to mediate nitrogen (N) and phosphorus (P) in runoff water from a commercial nursery over a period of 38 months. Maximum oxidized nitrogen [nitrate-N (NO3-N) + nitrite-N (NO2-N)] inputs occurred during the spring fertilization period of March through May (11.1 to 29.9 mg·L–1 N) and minimum inputs occurred during winter plant dormancy between December and February (2.8 to 5.2 mg·L–1 N). Nitrogen remediation efficiency averaged 94.7% for March through November sampling dates but declined to a mean of 70.7% between December and February when mean wetland water temperature dropped below 15 °C. Orthophosphate phosphorus (PO4-P) concentrations in nursery runoff showed no dramatic changes over months, seasons, or years. Mean wetland influent orthophosphate concentration ranged from 0.7 to 2.2 mg·L–1 PO4-P with an overall mean of 1.41 mg·L–1 PO4-P for all months sampled. Mean discharge orthophosphate concentration ranged from 0.5 to 2.1 mg·L–1 PO4-P with a mean of 1.45 mg·L–1 PO4-P. Phosphorus remediation efficiency varied widely and there was no correlation with water temperature. This 9.31-acre surface-flow constructed wetland was highly efficient at removing N from nursery runoff from a 120-acre catchment (large container production area), although it failed to consistently lower orthophosphate levels in runoff. This type of constructed wetland is suitable for removing oxidized N forms from nursery runoff and, depending on size, is capable of handling the large volumes of runoff generated by medium to large nursery and greenhouse operations.

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