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排序方式: 共有86条查询结果,搜索用时 15 毫秒
81.
Phyllis Randle 《Scientia Horticulturae》1983,20(1):53-59
Temperatures were recorded throughout cross-sections of mushroom compost stacks, and the effect of insulating part of the stack was studied. The mean temperature throughout the total cross-section in the insulated part of the stacks was 5° C higher than in the uncovered part of the stacks. Isotherms were drawn on scaled diagrams at 10° C intervals. The areas between the isotherms were calculated and presented as cumulative frequency curves based on percentages of the total cross-sectional area; this was a useful way of assessing areas of the stack within optimum temperature ranges for different groups of microorganisms.The functions of temperature gradients in compost stacks and the possible value of covering compost stacks were discussed. 相似文献
82.
Julia E Napier Suzan Murray Michael M Garner Tabitha Viner Hayley Murphy 《Journal of zoo and wildlife medicine》2005,36(4):709-711
Uterine leiomyomas occurred in three eastern bongo (Tragelaphus eurycerus isaaci) 10, 15, and 16 yr of age at three separate zoological institutions. Two animals were nulliparous, and one had given birth to 14 calves over its lifetime. Two of the leiomyomas originated in the cervix. The third originated in the uterine wall and incorporated the body of the uterus and both uterine horns. The tumors in the two animals that had never calved were large and nonresectable. They were associated with gastrointestinal clinical signs including diarrhea, anorexia, and the inability to defecate. The tumor in the animal that had calved was an incidental finding at necropsy. Uterine leiomyomas have not been previously documented in the literature on eastern bongo. 相似文献
83.
The islands of Tonga, in Western Polynesia, lacked rodents prior to human colonization. During the past 3000 years, people have introduced three species of rats (Rattus). Seed predation by rodents structures plant communities in many parts of the world. Therefore, there is the potential for rats to have a significant impact on the regeneration of plant communities in Tonga. We found 53 husking stations—sheltered sites used by rats to strip inedible protective structures (husks) from the seeds they eat—on eight islands in Tonga. The stations contained 13,555 empty husks from at least 18 plant species, but only 165 viable seeds and seedlings. These husking stations provide evidence of seed predation by rats. Determining the extent to which seed predation threatens plant regeneration will be important for conservation of native forest remnants. 相似文献
84.
Soil carbon and nitrogen storage in alluvial wet meadows of the Southern Sierra Nevada Mountains,USA
Jay B. Norton Hayley R. Olsen Laura J. Jungst David E. Legg William R. Horwath 《Journal of Soils and Sediments》2014,14(1):34-43
Purpose
Wet meadows formed on alluvial deposits potentially store large amounts of soil carbon (C) but its stability is subject to the impacts of management practices. The objective of this study was to quantify and characterize soil organic carbon (SOC) and nitrogen (N) in mountain wet meadows across ranges of meadow hydrology and livestock utilization.Materials and methods
Eighteen wetlands in the southern Sierra Nevada Mountains representing a range of wetness and livestock utilization levels were selected for soil sampling. In each wetland meadow, whole-solum soil cores delineated by horizon were analyzed for total and dissolved organic C (DOC) total (TN) and mineral nitrogen and soil water content (SWC). Multiple regression and GIS analysis was used to estimate the role of wet meadows in C storage across the study area landscape.Results and discussion
Average solum SOC contents by wetland ranged from 130 to 805 Mg ha?1. All SOC and TN components were highly correlated with SWC. Regression analyses indicated subtle impacts of forage utilization level on SOC and TN concentrations, but not on whole-solum, mass-per-area stocks of SOC and TN. Proportions of DOC and TN under seasonally wet meadows increased with increasing utilization. GIS analysis indicated that the montane landscape contains about 54.3 Mg SOC ha?1, with wet meadows covering about 1.7% of the area and containing about 12.3% of the SOC.Conclusions
Results indicate that soil organic C and N content of meadows we sampled are resilient to current light to moderate levels of grazing. In seasonally wet meadows, higher proportions of DOC and N with increasing utilization indicate vulnerability to loss. Partial drying of the wettest and seasonally wet meadows could result in losses of over five % of landscape SOC. 相似文献85.
Lefsrud MG Kopsell DA Kopsell DE Randle WM 《Journal of agricultural and food chemistry》2006,54(5):1764-1771
Selenium (Se) is a micronutrient in mammalian nutrition and is accumulated in kale (Brassica oleracea L. var. acephala), which has high levels of lutein and beta-carotene. Selenium, lutein, and beta-carotene have important human health benefits and possess strong antioxidant properties. The objectives of this study were to determine the influence of different Se [as sodium selenate (Na(2)SeO(4)) and sodium selenite (Na(2)SeO(3))] fertility levels on (1) biomass accumulation, (2) the accumulation patterns of carotenoid pigments, and (3) elemental accumulation in the leaves of kale. Winterbor kale was greenhouse-grown using nutrient solution culture with Se treatment concentrations of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 mg Se/L as Na(2)SeO(4) and 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mg Se/L as Na(2)SeO(3). Increases in either selenate (SeO(4)(-)(2)) or selenite (SeO(3)(-)(2)) resulted in decreases in kale leaf tissue biomass. Neither of the Se treatments had an effect on the accumulation of lutein or beta-carotene in leaf tissues. Increasing SeO(4)(-)(2) significantly increased the accumulation of kale leaf Se; however, leaf tissue Se did not significantly change over the SeO(3)(-)(2) treatments. Increases in SeO(4)(-)(2) affected the leaf tissue concentrations of P, K, Ca, Mg, S, B, Cu, Mn, and Mo, whereas SeO(3)(-)(2) only affected B and S. Growing kale in the presence of SeO(4)(-)(2) would result in the accumulation of high levels of tissue Se without affecting carotenoid concentrations. 相似文献
86.
K. M. S. Tennakoon Hayley J. Ridgway Marlene V. Jaspers E. Eirian Jones 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(1):87-99
Botryosphaeria stem blight is an economically important disease of blueberry worldwide. In this study, factors affecting inoculum production, infection and disease progression of Neofusicoccum spp. in blueberries were investigated. Under laboratory conditions conidia of the main three Neofusicoccum species (N. australe, N. parvum and N. ribis) were released from pycnidia at 15–30 °C and under relative humidities (RHs) of 80–100%, with greatest numbers released by N. parvum. The greatest numbers of oozing pycnidia and conidial release occurred at higher temperatures (25–30 °C) and RHs (92–100%). Inoculation of green shoots with different N. parvum and N. ribis conidial concentrations (50 μL of 5 × 104?5 × 106 conidia/ mL) caused 100% incidence but lesion lengths increased with increasing concentrations. Wound age affected N. ribis lesion development, with lesions only observed for 0–7-day-old wounds in soft green shoots and 0–4-day-old wounds for both hard green shoots and trunks. Colonisation length decreased with increasing wound age. Lesions developed on wounded shoots when plants were exposed to 20 or 25 °C and 90 or 100% RH during the early infection processes; and in non-wounded shoots spot-like lesions were observed although N. ribis colonised the stem tissue. Seasons (summer, autumn and winter) had no effect on susceptibility of wounded plants to N. ribis. External lesions only developed in summer-inoculated plants and colonisation length was lower in winter-inoculated plants. Information on host and environmental factors that affect disease development determined by the study will be used to inform the development of control strategies. 相似文献