Auswirkungen des Agroforestry-Anbausystems auf den Mineralstickstoffgehalt und das Matrixpotential in einer Parabraunerde sowie das Wachstum von Acer Pseudoplatanus

Effects of the agroforestry land use system on mineral nitrogen content and water potential in a Haplic Luvisol and on growth of Acer pseudoplatanus Results from three years are presented for an agroforestry system with Acer pseudoplatanus without (bare soil, treated with herbicides) and with undercropping, which was either Lolium perenne or Trifolium repens. The soil, a Haplic Luvisol derived from loess, had been intensively cultivated by agricultural crops before. Without undercropping leaching of nitrate was observed especially in the first, but also in the following years of the experimental period. This is due to the low and late N-demand of trees. Remaining contents of mineral nitrogen in the soil were sufficient for an optimal tree growth. With Lolium perenne as undercrop the mineral nitrogen content in the soil decreased in 0–60 cm depth as a result of N-uptake already in the first year. Leaching was observed from 60–90 cm depth. In the following years mineral nitrogen contents of the soil remained low, and were not sufficient for an optimal tree growth. Tree growth was further affected because of competition for water between gras and trees. With Trifolium repens mineral nitrogen in the soil was much higher than the demand for trees and undercrop due to symbiontic N-fixation by clover with subsequent mineralization. Although low water potentials were recorded similar to gras, competition for water did not diminish tree growth. Hence, optimal tree growth is guaranteed, but leaching of nitrate cannot be avoided. For all treatments leaching of N occured also in early spring. Up to now, there was no difference of tree growth between bare soil and Trifolium repens as undercrop, tree growth was much affected by Lolium perenne as undercrop.     

Einfluss von mechanischen Ber��hrungsreizen auf das Wachstum von K��chenkr?utern im Topf

For a compact growth of many potted plants you often have to use chemical growth inhibitors. Various species of herbs tend to an undesirable extension growth too. In general, the use of chemical inhibitors is prohibited in the production of potted herbs. For several years at the State Horticultural College and Research Institute Heidelberg there is employed an alternative method of mechanical stimulation treatment for a compact growth of potted plants. The greatest reduction of elongation was obtained, when the plants were treated with breaks in the early morning. In 2009 and 2010, the employees of the trial station proofed the effect of mechanical stimulation (Thigmomorfogenesis) to a large assortment of organically produced potted herbs. Green and red varieties of basil, parsley, coriander, chervil, lemon balm (2009) and four different varieties of mint (2010) were stimulated with a machine one week after beginning culture continuously 108 times per day. Compared to the untreated plants all mechanically stimulated herb species and varieties showed a tendency or significantly reduced elongation growth and therefore more stability. Depending on species and varieties the quality of these plants was visibly improved.     

输送形式对小麦辐照剂量分布的影响

以10MeV输出能量、4.3kW功率、218Hz扫描频率的电子束处理小麦,研究小麦在常规水平式输送带上和上倾斜式输送槽中被照射后的剂量分布和剂量均匀度系数。结果表明:当上倾斜角为3.3°、小麦流层厚度为50mm时可获得理想的剂量分布和合理的剂量均匀度系数。与现有的商业化辐照谷物杀虫处理装置相比,不但辐射能得到充分的利用,而且生产效率几乎相同。     

华北平原不同粮作模式下作物水分利用

利用田间定位试验的研究方法,对在华北地区通过种植模式调整实现农业节水的潜力进行了研究.通过系统比较3种不同种植模式单季和周年作物水分利用效率以及水量平衡方程,获得如下结论:1)冬小麦-夏玉米一年两熟常规模式(对照)具有显著产量优势,但水分利用率较低,对地下水消耗较大,不利于本地区农业的可持续发展;2)与对照相比,春玉米一熟模式可以实现最小灌溉或者零灌溉,充分利用自然降雨的同时,还有助于地下水的恢复,但周年产量降低较多(降低41％),考虑到粮食安全的需求,该模式不适宜在当前推广;3)与对照相比,两年三熟模式3年总灌溉量降低48％,产量降低11％,节水效果明显,水分利用效率显著提高,该模式进一步完善后可适当推广.本研究结果为在华北平原地区兼顾粮食安全基础上拓展节水农业提供了新的思路,对发展可持续性农业做了有益探索.     

Conversion of tropical moist forest into cacao agroforest: consequences for carbon pools and annual C sequestration

Tropical forests store a large part of the terrestrial carbon and play a key role in the global carbon (C) cycle. In parts of Southeast Asia, conversion of natural forest to cacao agroforestry systems is an important driver of deforestation, resulting in C losses from biomass and soil to the atmosphere. This case study from Sulawesi, Indonesia, compares natural forest with nearby shaded cacao agroforests for all major above and belowground biomass C pools (n = 6 plots) and net primary production (n = 3 plots). Total biomass (above- and belowground to 250 cm soil depth) in the forest (approx. 150 Mg C ha^?1) was more than eight times higher than in the agroforest (19 Mg C ha^?1). Total net primary production (NPP, above- and belowground) was larger in the forest than in the agroforest (approx. 29 vs. 20 Mg dry matter (DM) ha^?1 year^?1), while wood increment was twice as high in the forest (approx. 6 vs. 3 Mg DM ha^?1 year^?1). The SOC pools to 250 cm depth amounted to 134 and 78 Mg C ha^?1 in the forest and agroforest stands, respectively. Replacement of tropical moist forest by cacao agroforest reduces the biomass C pool by approximately 130 Mg C ha^?1; another 50 Mg C ha^?1 may be released from the soil. Further, the replacement of forest by cacao agroforest also results in a 70–80 % decrease of the annual C sequestration potential due to a significantly smaller stem increment.     

Mating patterns and pollen dispersal in four contrasting wild cherry populations (Prunus avium L.)

Although pollen dispersal has been extensively studied in trees, parameters influencing between-population variation are still poorly understood. In this study, we conducted paternity analyses on open-pollinated seeds in four natural populations of wild cherry (Prunus avium) with contrasting density and clonal propagation, using eight microsatellite loci and one self-incompatibility system locus. We also measured four quantitative traits and spatial positions as potential correlates of reproductive success. Levels of polyandry differed among populations and 30% of the seed families exhibited unequal paternal contributions, suggesting variation in reproductive success rather than variation in mate availability. Mating occurred preferentially among neighbours in all populations, suggesting that it is a common pattern in wild cherry and probably results from pollinator behaviour. Paternal success was positively correlated with diameter at breast height, as indicated in previous studies and tree dominance only resulted in higher paternal success in low density plots. Mating patterns were thus also affected by both density and tree size. Large-scale studies are needed to disentangle relative influences of these factors on the mating system and pollination success.     

Humic acid composition and soil fertility of soils near an ancient charcoal kiln: are they similar to Terra Preta de Índios soils?

Journal of Soils and Sediments - Charcoal production during the nineteenth century transformed landscapes in the Brazilian Atlantic Forests in Rio de Janeiro city. These paleo-territories were...     

Der Einfluß künstlicher vertikaler Grobporen in einer verdichteten Bodenmatrix auf das Wachstum von Winterweizen I. Wachstum von Winterweizen auf einer Parabraunerde aus Löß

The influence of artificial vertical macropores in a compacted soil on the growth of winterwheat. I. Growth of winterwheat on an alfisol derived from loess In field experiments on a compacted alfisol it was investigated, how artificially made vertical macropores in the compacted structure influence water extraction and growth of winterwheat compared to the compacted structure without vertical macropores and to the loosened structure. The experiments were carried out in two subsequent years with different precipitation (308, 0 and 440, 1 mm in the period of November until August of both growth periods). The influence of the different soil structure was most pronounced during periods of increasing water tension. Compared to the compacted structure, water extraction as well as yield was improved by the vertical artificial macropores to a similar extend as by the loosened structure. Both structures increased water extraction from deeper parts of the soil (25-50 cm). The beneficial effects of the vertical macropores were more pronounced in the dry compared to the wet year. Despite of the unequal distribution of roots in the compacted structure with vertical macropores, water extraction from the soil between the macropores was not negatively affected.     

Therapeutic approaches targeting the prion receptor LRP/LR

Transmissible spongiform encephalopathies known as prion diseases are a group of fatal neurodegenerative disorders that affect both humans and animals. The generally accepted principle of the disease is that the conversion of the cellular prion protein (PrP(c)) into the disease associated isoform PrP(Sc) leads to spongiform degeneration of the brain and amyloid plaque formation. Until now no therapy leading to potential alleviation or even cure of the disease exists. It is therefore important to develop therapeutic approaches for the treatment of TSEs since these infections are inevitably fatal and, especially in the case of vCJD, they affect youngsters. Besides current conventional therapeutic strategies, this review summarizes new therapeutic tools targeting the prion receptor LRP/LR.