草坪草离体再生培养的研究现状及发展前景

草坪业是近年来我国兴起的一个新产业.草坪草的品质直接关系到草坪的质量和寿命.为了适应当前草坪业的需要,科学工作者不断寻求各种途径选育新品种.离体再生培养无疑是其中十分有效的手段之一.主要阐述了草坪草离体再生培养的研究意义和现状,并展望了离体再生培养应用于草坪草新品种选育的美好前景.     

Effects of deposition of deer dung on nutrient redistribution and on soil and plant nutrients on intensively grazed grasslands in lowland Nepal

Nutrient redistribution, deer response to areas containing dung, and plant and soil nutrient content on grazing lawns and adjacent control areas were studied on intensively grazed grasslands in humid lowland Nepal. Effects of experimental fertilisation of grasslands with different amounts of dung pellets were also studied. A high-density population of axis deer recirculated 13 tons (dry mass, DM) of dung per month in the 10 km² study area. Because of preferential use of the grasslands for feeding while resting elsewhere, 10 tons were lost from the grassland to other habitat types per month during the dry season (February–May). The N, P, K, Na, and Mg content of grass from grazing lawns was significantly higher, probably because the grass was kept in a younger phenological stage of growth. In contrast with results from many other studies, the nutrient content of lawn soil was similar to that of adjacent, less intensively grazed areas, apart from P, which was lower in lawn soils. High plant P requirement on grazing lawns and removal of nutrients by deer may explain low soil P levels. Experiments with pellet fertilisation showed that high dung deposition increased plant P content, probably because of increased P uptake during early stages of growth. Dung deposition did not affect deer grazing preferences.     

Characteristics of methane emission fluxes in the Zoigê Plateau wetland on microtopography

AimsThe Zoigê Plateau, as a very important wetland distribution region of China, was the major methane (CH₄) emission center of the Qinghai-Xizang Plateau. The objective of this study is to study the effects of microtopographic changes on CH₄ emission fluxes from five plots across three marshes in the littoral zone of the Zoigê Plateau wetland.
Methods CH₄ emission fluxes were measured in five plots across three marshes in Zoigê Plateau wetland using the closed chamber method and Fast Greenhouse Gas Analyzer from May to October in 2014.
Important findings During the growing season, mean CH₄ emission fluxes from the permanently flooded hollow (P-hollow) and hummock (P-hummock) in the Zoigê Plateau wetland were 68.48 and 40.32 mg·m^-2·h^-1, while mean CH₄ emission fluxes from the seasonally flooded hollow (S-hollow) and hummock (S-hummock) were 2.38 and 0.63 mg·m^-2·h^-1. CH₄ emission fluxes from non-flooded lawn was 3.68 mg·m^-2·h^-1. Mean CH₄ emission fluxes from five plots across three sites was 23.10 mg·m^-2·h^-1, with a standard deviation of 30.28 mg·m^-2·h^-1 and the coefficient of variation was 131%. We also found that there was a significant and positive correlation between mean CH₄ emission fluxes and mean water table depth in the five plots across three sites (R² = 0.919, p < 0.01), indicating that water table depth was controlling the spatial variability of CH₄ emission fluxes from the Zoigê Plateau wetland on microtopography. CH₄ emission fluxes in the P-hollow, P-hummock, and S-hummock showed an obvious seasonal pattern, which was not observed in the lawn and S-hollow. However, CH₄ emission peaks were observed in all the plots during summer and/or autumn, which could be closely related to the water table depth, soil temperature, and the magnitude of litter mass. In addition, we found that the CH₄ emission flux in the P-hollow was much higher than the other four plots in the Zoigê Plateau wetland, suggesting that CH₄ in the P-hollow could be often transported to the surface by ebullition and CH₄ emission from the Zoigê Plateau wetland may be under estimated in the past.     

京郊草坪蛴螬的种类和为害特点

2004–2006年,在北京及周边地区对草坪生产基地、绿化草坪、高尔夫球场草坪及运动场草坪地下害虫蛴螬种类和为害进行了调查。共鉴定蛴螬2 220头,隶属2亚科10属17种,其中华北大黑鳃金龟、黄褐丽金龟和铜绿丽金龟是重要的为害种。提供了鉴别特征图和北京地区草坪蛴螬种类检索表。     

广东省草皮种植场和城市草坪红火蚁发生为害程度调查

[背景]在防控红火蚁的工作中,有效控制该虫传播途径、降低传播风险是预防的关键。随草皮调运传播是红火蚁扩散的重要方式之一。[方法]采用活蚁巢密度、诱集比率、诱集工蚁数量、发生率等多个指标,调查评价了广东省主要草皮种植地区广州石基、广州增城、深圳南山、惠州博罗等草皮种植场和城市绿化草坪红火蚁发生程度。[结果]广东省草皮种植场红火蚁发生普遍,携带该虫扩散传播的风险极大。不同地区草皮种植场红火蚁发生程度存在明显差异。惠州博罗草场红火蚁发生程度最重,活蚁巢密度、诱集比率、诱集工蚁数量和发生率分别为0．0085个·m^-2、56．75％、16．80头·个^-1和83．60％;深圳南山发生程度最轻,各项指标分别为0．0011个·m^-2、9．62％、0．92头·个^-1和24．50％。城市绿化草坪红火蚁发生较为普遍。调查的3个城市中惠州发生程度最重,活蚁巢密度、诱集比率、诱集工蚁数量和发生率等均最高,分别为0．0149个·m2、10．46％、14．30头·个-1和62．86％。不同品种草坪草红火蚁发生程度不同,以假俭草最高,以上4个指标分别为0．0140个·100m^-2、6．85％、5．57头·个^-1和51．43％。城区类型不同红火蚁发生程度不同,老城区红火蚁发生较轻,新城区较重,发生点常在移植草坪、绿化苗木区域。[结论与意义[广东省主要草皮种植区和城市草坪红火蚁发生均较为普遍,运输携带该虫传播的风险极大,研究结果可为加强草皮检疫、防止携带红火蚁传播提供依据。     

Urbanization can accelerate climate change by increasing soil N2O emission while reducing CH4 uptake

Urban land-use change has the potential to affect local to global biogeochemical carbon (C) and nitrogen (N) cycles and associated greenhouse gas (GHG) fluxes. We conducted a meta-analysis to (1) assess the effects of urbanization-induced land-use conversion on soil nitrous oxide (N₂O) and methane (CH₄) fluxes, (2) quantify direct N₂O emission factors (EF_d) of fertilized urban soils used, for example, as lawns or forests, and (3) identify the key drivers leading to flux changes associated with urbanization. On average, urbanization increases soil N₂O emissions by 153%, to 3.0 kg N ha⁻¹ year⁻¹, while rates of soil CH₄ uptake are reduced by 50%, to 2.0 kg C ha⁻¹ year⁻¹. The global mean annual N₂O EF_d of fertilized lawns and urban forests is 1.4%, suggesting that urban soils can be regional hotspots of N₂O emissions. On a global basis, conversion of land to urban greenspaces has increased soil N₂O emission by 0.46 Tg N₂O-N year⁻¹ and decreased soil CH₄ uptake by 0.58 Tg CH₄-C year⁻¹. Urbanization driven changes in soil N₂O emission and CH₄ uptake are associated with changes in soil properties (bulk density, pH, total N content, and C/N ratio), increased temperature, and management practices, especially fertilizer use. Overall, our meta-analysis shows that urbanization increases soil N₂O emissions and reduces the role of soils as a sink for atmospheric CH₄. These effects can be mitigated by avoiding soil compaction, reducing fertilization of lawns, and by restoring native ecosystems in urban landscapes.     

马尼拉草特性及建坪技术研究

本文报道了马尼拉草生态习性、生长特性的观察和建坪的技术措施研究。证明马尼拉草是适应性广、抗逆性强、成坪块、绿期长、耐践踏的优良草种,其建坪技术措施是：合理选择铺植方式,把好整地、改土、植栽、管理技术关,就可在广西各地建成景观效果佳的草坪。     

Activity spectra of Bacillus Thuringiensis δ-endotoxins against eight insect cell lines

Summary Eight continuous insect cell lines were tested for susceptibility to the δ-endotoxins of several lepidopteran-active strains and cloned-gene products of Bacillus thuringiensis. The assays were performed on cells suspended in agarose gel, which allowed the toxins activated at pH 10.5 to be applied directly in a high-pH buffer without causing solvent toxicity to the cells. The responses of the cell lines to the various toxins produced activity spectra that were used to identify functionally similar and dissimilar toxin proteins. IPRI-CF-1 and FPMI-MS-5, derived from neonate larvae of Choristoneura fumiferana and Manduca sexta, respectively, exhibited the greatest sensitivity to the toxins tested, whereas B. thuringiensis subsp. entomocidus had the broadest in vitro host range. Analysis of activity spectra led to the identification of the particular Cry protein that was responsible for the broad toxicity of this subspecies and demonstrated a distinct difference in toxin composition between two strains of subsp. sotto. The identical spectra observed for subsp. kurstaki HD-1 and NRD-12 is consistent with insect bioassay data obtained previously by other workers and supports the conclusion that there is virtually no difference in activity between these two strains. The in vitro assay system, referred to as the “lawn assay” and used to test B. thuringiensis activated toxins against insect cell lines, is particularly useful in mode-of-action studies and as a rapid, preliminary test for the presence of specific cytolytic proteins, rather than as a method for screening toxins of wild-type strains for insecticidal activity. The response of cells in vitro to B. thuringiensis toxins is often very different from that of the insect from which the cells were derived.     

Spatial micro‐patterns in the steppe of Tierra del Fuego induced by sheep grazing

Abstract. In the Festuca gracillima tussock steppe of northern Tierra del Fuego there is a physiognomic pattern at the community scale composed of a matrix of tussocks, scrub patches of Chiliotrichum diffusum and lawn patches. In this paper we compared floristic composition, soils, microclimate and sheep use of these three types. Species composition greatly differed among physiognomic types. Lawn patches showed the highest diversity and maximum cover of exotics, grazing escape growth forms and species of high‐fertility habitats. Soil profiles of tussock steppe and lawn were similar but the A‐horizon of the latter contained more clay and cations. Radiation and temperature during daylight at the soil surface in summer were highest in the lawn patches. Soil impedance, a good indicator of trampling, was highest on the lawn patches. According to dung pellet density, lawn patches received much heavier use than the tussock matrix. Our results suggest that lawn patches supported the highest grazing impact and undergo a eutrophication process favoured by high mineral inputs, high mineralization rates in the soil during the warm season and restricted leaching through the profile. They also support the idea that a feedback mechanism between vegetation heterogeneity and sheep grazing behaviour maintains the patches. Although grazing behaviour suggests that the lawn patches favour animal production, their expansion would result in a system less protected against the impact of water deficits and temperature variations and more vulnerable to erosion and to the loss of important species.