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951.
Harald Dinkelmeyer Johannes Lehmann Andreas Renck Lucerina Trujillo Jose Pereira da Silva Jr Gerhard Gebauer Klaus Kaiser 《Agroforestry Systems》2003,57(3):213-224
Mixed tree cropping systems have been proposed for sustainable nutrient management in the humid tropics. Yet, the nutrient interactions between intercropped trees have not been addressed sufficiently. In the present study we compare the temporal and spatial patterns of the uptake of applied 15N by four different tree crops in a mixed tree cropping system on a Xanthic Ferralsol in central Amazônia, Brazil, during one year. Most of the N uptake occurred during the first two weeks. Very little N was recovered by peach palm (Bactris gasipaes), more by cupuassu (Theobroma grandiflorum) and annatto (Bixa orellana) and most by Brazil nut (Bertholletia excelsa). Due to tree pruning the total accumulation of applied 15N in the above-ground biomass of annatto decreased throughout the year. It remained constant in cupuassu and peach palm and increased in Brazil nut. Brazil nut showed an extensive root activity and took up more fertilizer N applied to neighboring trees than from the one applied under its own canopy in contrast to the other three tree crops. Therefore, trees with wide-spread root systems may not need to receive N fertilizer directly but can take up N applied to other trees in the mixed cropping system. This means that such trees may effectively decrease N leaching when intercropped with trees that have dormant periods or places with low N uptake, but also exert considerable resource competition.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
952.
Fan Hui Li Jiquan Jin YoujuCollege of Biological Sciences Biotechnology Beijing Forestry University Beijing P. R. China 《中国林学(英文版)》2003,(1)
Electrophysiological and behavioral responses of adult A. glabripennis (Motsch.) to volatiles from ashleaf maple (Acer negundo L.) were investigated to identify semiochemicals involved in host location. Measurable electroantennogram (BAG) responses were elicited to all compounds tested, the most effective antennal stimulants were trans-2-hexen-1-al,decyl aldehyde and trans-2-hexenl-ol.These profiles were similar between males and females. In Y-tube olfactometer bioassays, above three compounds with certain concentration, trans-2-hexen-l-al (1%), trans-2-hexen-l-ol (1%) and decyl aldehyde (10%), were significantly attractive to the adults in laboratory. The results show that either BAG or olfactory responding to a particular volatile compound are markedly influenced by the concentration. 相似文献
953.
Studies on Heavy Metal Pollution in Soil—Plant System:A Review 总被引:2,自引:0,他引:2
WangHaiyan SunXiangyang 《中国林学(英文版)》2003,5(1):55-62
Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry.The heavy metal pollution status in soil-plant system in China,the research progress on the bioavailability of heavy metals (effecting factors,extraction methods,free-ion activity model,adsorption model,multivariate regression model,Q-I relationship,and compound pollution),and soil remediation are reviewed in paper.Future research and monitoring is also discussed. 相似文献
954.
绿竹 (Dendrocalamopsisoldhamii)属禾本科竹亚科绿竹属 ,原产我国 ,集中分布浙江南部、台湾、福建及广西、广东等省 (区 )。在浙江、台湾、福建三省普遍栽培 ,是亚热带地区优良速生的笋材两用的丛生竹种之一。绿竹笋味鲜美 ,清凉解暑 ,同时具有降压、降脂、增强消化系统功能的作用 ,是夏秋两季深受群众喜爱的美味佳肴。绿竹竹材易降解 ,是应用前景广阔的造纸原料。近年来 ,以笋用林为主要经营目的的绿竹林发展很快 ,并取得不少的经验 (张文燕等 ,1 999;郑文汉等 ,1 997;董建文 ,2 0 0 0 )。叶片作为最主要的同化器官在竹林生长发育过程中起着重要作用 ,研究竹叶片生理生化特性 ,揭示叶片生长发育规律 ,对指导竹林栽培具有重要意义。当前对竹子叶片生理生化特性的研究已有过不少报道 ,如毛竹(Phyllostachysheterocyclacv .pubescens) (郑郁善等 ,1 998;黄启胜等 ,1 989)、麻竹 (Dendrocalamuslatiflorus)(邱尔发等 ,2 0 0 1 ;2 0 0 2 )、雷竹 (Phyllostachyspraecoxf.pre... 相似文献
955.
956.
We tested the dynamics of nine enzymes during leaf litter decomposition in Xishuangbanna tropical rain-forest both in the
field and laboratory to explore the response of enzyme dynamics to decomposition under different food-web structures. We used
coarse and fine (1 mm and 100 μm mesh size, respectively) litterbags in the field to create different food-web structures
during litter decomposition. Most soil macrofauna such as nematodes could access only the coarse mesh litterbags, leaving
only microbiota, such as mites, in the fine mesh litterbags. In the laboratory, sterilization and inoculation were adopted
to investigate different enzyme dynamics with nematodes or only microbiota participating in litter decomposition. Invertase
and amylase increased more for shorter food webs at the early stages of decomposition, while activities of endocellulase,
β-glucosidase, xylanase and polyphenoloxydase increased to their maxima at the later stages, but greater increase occurred
with extended food webs. Invertase and amylase had negative relationships and endocellulase, β-glucosidase, xylanase and polyphenoloxydase
had positive relationships with litter decomposition (mass loss). The activities of enzymes responded to the process of litter
decomposition. Invertase and amylase played key roles for microbiota utilizing the substrates at early stages of decomposition,
while endocellulase, β-glucosidase, xylanase and polyphenoloxydase worked on the further decay of recalcitrant compounds at
later stages. All enzymes related to carbon decay acted as effective indicators of litter decomposition. The decomposition
of plant organic matter was essentially an enzymatic process.
__________
Translated from Journal of Plant Ecology (Chinese Version), 2008, 32(3): 622–631 [译自: 植物生态学报] 相似文献
957.
Liang He Ning Yin Jun-Wen Cheng Xue-Qian Wu Jian-Xin Jiang Xian-Liang Song 《Fitoterapia》2009,80(7):399-403
Water-soluble polysaccharides were extracted from the fruit pulps of Melia azedarach and some columns were undertaken to isolate the major polysaccharide (MPS-III). Its structural features were elucidated by IR analysis, carbohydrate analysis, periodate oxidation, Smith degradation, methylation analysis and NMR spectroscopy. Then it was evaluated for the cytotoxic activity in vitro against four human cell lines, using the sulphorhodamine B assay. The data obtained indicated that MPS-III contains a α(1→4) main chain backbone composed of arabinose, mannose in a molar ratio of 1.31:1.0 and has α(1→6) branch structure. And MPS-III showed a strong cytotoxic activity in the BGC-823 cell line. 相似文献
958.
银杏酸单体制备及其抗菌活性 总被引:3,自引:0,他引:3
以银杏外种皮为原料,石油醚回流提取得粗提物,经硅胶柱色谱分离、纯化得银杏酸(GA)混合物,再经制备色谱柱多次分离,反复制备得到6种单体:银杏酸C13:0、C15:1、C17:2、C15:0、C17:1和一种未知新化合物,各单体纯度都达95%以上,可作为银杏产品中有毒成分银杏酸定量分析的对照品,初步鉴定该未知物是一种新的银杏酸。测定了粗提物、银杏酸混合物及3种不同单体对17种植物病原菌的抗菌活性。结果表明,银杏酸是银杏外种皮中抗菌活性成分之一,不同银杏酸单体的抗菌活性存在差异,C13:0的抗菌活性显著高于C15:1和C17:1的活性,C15:1的活性高于C17:1银杏酸的抗菌活性与其化学结构中苯环上第六位取代基团有关。 相似文献
959.
纤维素酶抑制剂对松墨天牛消化生理的影响 总被引:6,自引:0,他引:6
以松墨天牛的消化生理为基础,研究了松墨天牛消化酶中纤维素酶的动力学特性;以现代酶学研究方法为主,结合生物测定技术,进一步研究了不同性质和不同浓度的酶抑制剂对松墨天牛成虫离体和活体纤维素酶酶活力的影响,结果表明,选用的酶抑制剂无论对分离提取的纤维素酶液和活体中的纤维素酶8都具有显著的抑制作用。饲养试验中,经0.1%酶抑制剂处理的饲料组5d死亡率为75%.ck组平均成活天数为28d。 相似文献
960.