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  • Author or Editor: Zhen Yang x
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Containerized ornamental plant production represents extremely intensive agricultural production. An average of 200,000 containers may occupy 1 acre of surface area, to which a large amount of chemical fertilizers will be applied. Because of the use of high-drainage soilless potting mixes coupled with excessive fertigation, a great amount of nutrients, particularly nitrogen and phosphorus, are leached, which increases the potential for ground and surface water contamination. Over the past 2 decades, research has been centered on developing fertigation delivery systems such as nutrient film techniques, ebb-and-flow and capillary mat systems, for reducing leaching. Relatively limited research has been conducted on improving potting medium substrates to minimize nutrient leaching. The objectives of this study were to determine the adsorption isotherm of six different zeolites to ammonium, nitrate and phosphorus, identify and incorporate desired zeolites in a peat/bark-based medium for reducing nutrient leaching in ornamental plant production. Results indicated that the zeolites possess great holding capacities for ammonium, nitrate, and phosphorus. Compared to control, ammonium leaching was reduced 70% to 90%, phosphorus 30% to 80% and nitrate 0% to 60% depending on zeolite species and quantity used per pot. Zeolite amended media caused no adverse effects on plant growth. Conversely, biomass increased significantly when compared to that of the control.

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The Chinese Incense-cedar (Calocedrus macrolepis Kruz), an important wood and ornamental tree, is native to southwest China and also in northern Vietnam, Laos, Thailand, and Myanmar. As a result of ecological degradation in these areas, Chinese Incense-cedar was considered a vulnerable species according to the criteria of the International Union for the Conservation of Nature and Natural Resources. In the current report, we developed and characterized 13 novel microsatellite markers for this species using the protocol of fast isolation by amplified fragment length polymorphism of sequences containing repeats. Polymorphism of each locus was assessed in 36 individuals from nine geographical populations. The number of alleles per locus ranged from two to nine with an average of 6.08. The observed and expected heterozygosities ranged from 0.0000 to 1.0000 and from 0.1549 to 0.8912 with averages of 0.6688 and 0.6815, respectively. Four of the 13 loci were significantly deviated from Hardy-Weinberg expectations. No significant linkage disequilibrium was detected. These polymorphic microsatellite markers would be useful tools for investigating genetic population structure and diversity to establish conservation strategy for this interesting and vulnerable species.

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