马里兰烟609雄性不育系转育与利用研究

[目的]为马里兰烟609雄性不育系(Msmd609)的大面积推广应用奠定基础。[方法]利用白肋烟MSBurley21雄性不育源与马里兰烟609(Md609)进行转育回交,获得Msmd609。分析Msmd609的遗传性状稳定性、田间抗病性、产量产值、均价、上中等烟比率、原烟外观质量及内在化学成分。[结果]Msmd609抗逆抗病性强,生长势强,农艺经济性状好,化学成分协调,评吸结果优良,适宜推广种植。[结论]该研究对解决马里兰烟种植品种单一、抗逆抗病性较差等问题,满足卷烟工业对马里兰烟原料需求具有重要的意义。     

马里兰烟品种比较试验研究初报

为筛选出适合云南保山种植并达到优质、适产、抗性好的品种,对7个马里兰烟品种进行了田间比较试验。结果表明:(1)品种Md872、Md609、Md40长势较好,Md40与Md10株高均高于对照(Md609),Md872株高接近对照,Wilson最低。各供试品种单株平均留叶数25.43片,高于对照,品种间差异不大。Md10、MdBL大田生育期84d,属中晚熟品种,Md872、Md40为91d。属晚熟品种。(2)7个品种在田间均发生烟草普通花叶病,Wilson发病率,比对照高1.5倍,高感花叶病;Md872、Md40发病率最低,比对照发病率低90.00%,高抗花叶病。供试品种的黑胫病发病率均高于对照,Md201、Wilson黑胫病发病率比对照分别高68.10%、62.10%,为黑胫病感病品种;Md872和Md40发病率相对较低。(3)供试品种中Md40、Md872的产量、产值、均价与对照Md609相比差异不显著,上等烟比例相对较高。(4)农艺性状、抗病性、经济性状综合比较,Md872、Md40较适宜在云南保山与对照Md609同时进行小规模种植示范。     

Electron donors and acceptors influence anaerobic soil organic matter mineralization in tidal marshes

Anaerobic decomposition in wetland soils is carried out by several interacting microbial processes that influence carbon storage and greenhouse gas emissions. To understand the role of wetlands in the global carbon cycle, it is critical to understand how differences in both electron donor (i.e., organic carbon) and terminal electron acceptor (TEA) availability influence anaerobic mineralization of soil organic matter. In this study we manipulated electron donors and acceptors to examine how these factors influence total rates of carbon mineralization and the pathways of microbial respiration (e.g., sulfate reduction versus methanogenesis). Using a field-based reciprocal transplant of soils from brackish and freshwater tidal marshes, in conjunction with laboratory amendments of TEAs, we examined how rates of organic carbon mineralization changed when soils with different carbon contents were exposed to different TEAs. Total mineralization (the sum of CO₂ + CH₄ produced) on a per gram soil basis was greater in the brackish marsh soils, which had higher soil organic matter content; however, on a per gram carbon basis, mineralization was greater in the freshwater soils, suggesting that the quality of carbon inputs from the freshwater plants was higher. Overall anaerobic metabolism was higher for both soil types incubated at the brackish site where SO₄²⁻ was the dominant TEA. When soils were amended with TEAs in the laboratory, more thermodynamically favorable respiration pathways typically resulted in greater organic matter mineralization (Fe(III) respiration > SO₄²⁻ reduction > methanogenesis). These results suggest that both electron donors and acceptors play important roles in regulating anaerobic microbial mineralization of soil organic matter.     

不同生态环境下施肥对马里兰烟的影响

为了解不同栽培环境对马里兰烟生长的影响,为生产优质马里兰烟提供科学施肥依据,在两个生态环境差别较大的地区,研究不同施肥量、钾/氮比以及氮素形态对马里兰烟的影响,结果表明：施氮量对产量的影响最大,而氮素形态也有影响,施用硝态氮不仅提高烟叶产量,还有助于降低烟碱含量,提高含钾量;在微碱性的土壤上,以及氮肥施用量超过120kg/hm2,增施钾肥对提高马里兰烟含钾量的效果较小,对烟叶外观品质的提高也不明显。为保持马里兰烟的特点,马里兰烟应种植在pH＜7.5的土壤上,适宜的氮肥施用量为120~150kg/hm2,硝态氮应占50%~75%,N:K可控制在1:3以内,土壤速效钾含量达到中等的可降低到1:1.5。     

不同生态环境下施肥对马里兰烟的影响

为了解不同栽培环境对马里兰烟生长的影响,为生产优质马里兰烟提供科学施肥依据,在两个生态环境差别较大的地区,研究不同施肥量、钾/氮比以及氮素形态对马里兰烟的影响,结果表明:施氮量对产量的影响最大,而氮素形态也有影响,施用硝态氮不仅提高烟叶产量,还有助于降低烟碱含量,提高含钾量;在微碱性的土壤上,以及氮肥施用量超过120kg/hm2,增施钾肥对提高马里兰烟含钾量的效果较小,对烟叶外观品质的提高也不明显。为保持马里兰烟的特点,马里兰烟应种植在pH<7.5的土壤上,适宜的氮肥施用量为120￣150kg/hm2,硝态氮应占50%￣75%,N:K可控制在1:3以内,土壤速效钾含量达到中等的可降低到1:1.5。     

Seed longevity in terrestrial orchids - Potential for persistent in situ seed banks

Terrestrial orchids typically produce numerous small seeds that contain very small nutrient reserves. The seeds are structurally adapted for wind dispersal but little is known about their fate after dispersal. Some studies of seed viability in situ indicate survival for up to two years in temperate orchid species. Seeds stored in the laboratory may last much longer. We investigated seed viability of seven North American orchid species with seed packets buried in a range of soil and wood substrates within their natural habitats. In Goodyera pubescens most seeds germinated within one year. Four other species continued to germinate sparsely during the observation period, but after almost seven years many seeds were still viable. In one species, Liparis liliifolia, seeds that had been in situ for four years had germination rates as high as 68% when sown in vitro with a compatible fungus. The remaining two species did not germinate during the observation period but the seeds were judged to be intact and tested positively for viability after four years in the ground. These observations are interpreted as different species-specific strategies for in situ germination and their seed bank potential is discussed.     

Placing the pieces: Reconstructing the original property mosaic in a warrant and patent watershed

Recent research shows that land use history is an important determinant of current ecosystem function. In the United States, characterization of land use change following European settlement requires reconstruction of the original property mosaic. However, this task is difficult in unsystematically surveyed areas east of the Appalachian Mountains. The Gwynns Falls watershed (Baltimore, MD) was originally surveyed in the 1600-1700s under a system of warrants and patents (commonly known as ‘metes and bounds’). A method for the reconstruction and mapping of warrant and patent properties is presented and used to map the original property mosaic in the Gwynns Falls watershed. Using the mapped mosaic, the persistence of properties and property lines in the current Gwynns Falls landscape is considered. The results of this research indicate that as in agricultural areas, the original property lines in the Gwynns Falls watershed are persistent. At the same time, the results suggest that the property mosaic in heavily urbanized/suburbanized areas is generally ‘reset.’ Further, trends in surveying technique, parcel size, and settlement patterns cause property line density and property shape complexity to increase in the less urbanized upper watershed. The persistence of original patterns may be damping expression of heterogeneity gradients in this urban landscape. This spatial pattern of complexity in the original mosaic is directly opposite of hypothesized patterns of landscape heterogeneity arising from urbanization. The technique reported here and the resulting observations are important for landscape pattern studies in areas settled under unsystematic survey systems, especially the heavily urbanized areas of the eastern United States. This revised version was published online in July 2006 with corrections to the Cover Date.     

氮磷钾配比对马里兰烟产量和品质的影响

为探索马里兰烟适宜的氮磷钾比例,在五峰县烟区进行试验,研究了氮磷钾比例对马里兰烟生长情况、产量和内在品质的影响.结果表明,当氮磷钾比例为1∶1∶3时,烟叶的经济性状最好,化学成分较适宜,烟叶评吸质量较好.在五峰烟区土壤中等肥力下,马里兰烟的氮、磷、钾最佳使用量分别为180、180、540 kg/hm2.     

Use of Best Management Practices and Pasture and Soil Quality on Maryland Horse Farms

Agricultural operations, including horse farms, can contribute nonpoint source (NPS) pollution to surface water. The use of best management practices (BMPs) is the most effective way to prevent the movement of pollutants to surface water from nonpoint source pollution. Previous mailed survey studies have assessed the use of BMPs at the county and state level, but a visual assessment of horse farms is necessary to validate survey results. An observational field study was conducted to assess BMP use and soil and pasture quality and to create a model to predict soil erosion on Maryland horse farms. Fifty-one farms were selected based on stocking density (acres per horse [ac horse^-1]), farm use, and presence of water on property. All farms were visited from September through November 2009. In each pasture with grazing horses, the correct use of BMPs was assessed, grass height and vegetative cover were measured, and composite soil samples were collected. Less than half of the 18 assessed BMPs were being used by participants. Although most participants maintained the recommended vegetative cover and grass height, soil erosion was a major problem in pastures. Most farms had optimum soil nutrient concentrations (Ca, K, and P), excessive Mg values, and basic soil pH. Vegetative cover and grass height measurements were positively correlated with stocking density (r = 0.345, P < .0001; and r = 0.291, P < .0001, respectively). Farm use was the only variable that predicted soil erosion on farms (P = .006). Farms used for pleasure were least likely to have soil erosion, whereas farms used for breeding were more likely to have soil erosion (P = .0058). Despite the low-to-moderate adoption of BMPs, the maintenance of recommended vegetative cover and grass height as well as optimum values of soil nutrients indicated participating Maryland horse farms have a low potential for nutrient movement and NPS pollution.