引进小麦种质材料的高分子量谷蛋白亚基分析

为了有效利用多年来引自俄罗斯及中亚地区的小麦资源,了解引进材料的遗传基础,特别是品质基础,采用SDS-PAGE技术对102份小麦材料的高分子量谷蛋白亚基（HMW-GS）组成进行了分析。结果表明,参试材料中共检测到11种HMW-GS类型,Glu-A1位点上有1、2＊、Null,Null位点相对比较多,为40.20%;Glu-B1位点上有7、7＋8、7＋9、6＋8、17＋18,以7＋9为主要类型（59.80%）;Glu-D1位点有2＋12、2＋12’、5＋10三种类型,其中5＋10所占比例为51.96%。参试材料共检测到16种亚基组合,其中＂Null,7＋9,2＋12＂所占比例较大,为25.5%。值得一提的是,参试材料中品质评分为10分的材料有22个,9分的有29个。这些材料有可能会成为比较有价值的品质改良中间材料。     

Dryland salinity and rainfall patterns: A preliminary investigation in central west New South Wales (Australia)

Dryland salinity is an increasingly serious land degradation problem in many parts of the world. Bare salinised ground leads to accelerated rates of sheet, rill and gully erosion; decreasing plant productivity; and declining surface water quality. In a given geological, climatic and land use situation, rainfall patterns may influence the changing extent of dryland salinity. This possibility was investigated for an area in Australia with long‐term rainfall records. Changes in salinisation were recorded using nine sets of aerial photographs. Saline sites fluctuated in size between photo‐years but their number and extent increased between 1958 and 1996, with sites along wash lines being especially responsive to rainfall variations. Saline areas generally decreased in size and number during the wet period from 1958 to the early 1970s, extended during drought years in the early 1980s, then increased markedly to 1996 during a period of above average rainfall. Three saline sites showed a broad inverse relationship between salinity (bare ground) extent and rainfall in the pre‐drought period but post‐drought trends showed increasing rainfall associated with increasing salinisation. Short‐term variations in salinity were superimposed on longer‐term expansion. Copyright © 2008 John Wiley & Sons, Ltd.     

Improving precision in sediment source and erosion process distinction in an upland catchment,south-eastern Australia

Analysis of sediment sources is an important component in the development of catchment sediment budgets and in determining links between erosion from sources and sediment delivery to catchment outlets. In this study ¹³⁷Cs and ²¹⁰Pb_ex were used to determine surface and sub-surface source contributions of fine sediment in a small upland headwater catchment (1.6 km²) in south-eastern Australia. The findings from this analysis are employed in an adjustment procedure to better differentiate sediment source erosion processes by utilising channel survey and erosion pin data. This improved the precision of estimates of sediment-source erosion-process contributions from hillslopes and channel/gully walls. A mean of 74% of in-channel deposits and suspended sediment exiting the study catchment was derived from sub-surface sources and when adjusted for erosion process this increased to 81%, which may be attributed to channel and gully wall erosion alone. Net erosion of the channel floor was low and constitutes only a small part of the total channel source input to sediment flux. Variability in sediment source contributions within the catchment was high, with rapid transition from hillslope to channel source dominance of sediment flux with distance downstream in the study catchment.     

Condition of rehabilitated coal mines in the Hunter Valley,Australia

Legislation requiring the rehabilitation of new opencast coal mines came into effect in New South Wales, Australia, in 1973. Mining companies now stockpile original topsoil which is later spread with fertilizer over re-shaped overburden and waste carbonaceous material. Problems in successfully revegetating new surfaces are exacerbated by the thinness and infertility of natural soils, which are deficient in phosphorus and moderately acid. Revegetation has not been successful on untreated mine waste and overburden. This study provides a general overview of some aspects of post-rehabilitation soil chemistry and vegetation on these soils. A limited number of samples, collected from three mine sites having different rainfall and varying ages of rehabilitated areas, were tested for pH, EC, organic carbon, total phosphorus and available aluminium. Rehabilitated areas were all characterised by very low levels of total phosphorus, neutral pH, and variable and relatively low organic carbon, and some showed aluminium toxicity. Heavy application of gypsum at one of the steeper sites was associated with acid pH, high EC values, low total P, Al toxicity, some soil erosion and little plant cover. Except for this site, the variable vegetation cover at the sites studied seemed adequate for long-term re-establishment, despite serious weed invasion at some non-studied sites, soil loss on newly re-formed surfaces, and generally poor natural and rehabilitated soils.     

Post-fire hillslope erosion response in a sub-alpine environment, south-eastern Australia

This paper examines post-fire erosion response in a sub-alpine environment in south-eastern Australia for a period of 2.2 years. Few studies have examined fire impacts on sediment transfer in this environment. Erosion pins were used in grids located at upper, mid and lower slope positions on adjacent burnt and unburnt hillslopes to assess fire effects on the extent of surface level change. The results indicated that there was a significant difference between the surface level change regimes on the burnt and unburnt hillslopes. Estimated erosion rates for the burnt slope over the study period ranged from 2.7 to 94.3 t ha^− 1, which could be considered low given the high slope angles, high precipitation and moderate fire severity. Slope position was critical in modifying post-fire erosion response, as it controlled slope angle and the rate of surface cover regrowth. Analysis of lower slope sites, for which more detailed data was available, indicated a second delayed erosion peak after the initial elevated post-fire response during the following spring snowmelt period. Surface recovery on the lower burnt site was slow, with vegetation cover still comparatively low 2.3 years after the fire. Evidence of post-fire sediment supply limitation was found on this site, with a declining rate of increase in the magnitude of total surface level change, despite limited regrowth and an increasing number of precipitation events > 20 mm for measurement intervals since the fire. Modification of the hillslope surface by fire leads to changing hillslope erosion process dominance in this environment. The post-fire hillslope undergoes erosion by direct rain-drop impact and overland flow, whereas the unburnt slope rarely experiences overland flow due to the thick ground cover. As a result surface level change on the unburnt slope was largely influenced by wetting–drying effects rather than sediment transfer by surface flow. Downslope biotransfer appears to be the dominant sediment movement process in the unburnt sub-alpine forest environment.