Tree row spacing affected agronomic and economic performance of Eucalyptus-based agroforestry in Andhra Pradesh, Southern India

The 3 × 2 m spacing currently used for eucalyptus plantations in the state of Andhra Pradesh, southern India does not permit intercropping from the second year. This discourages small landholders who need regular income from taking up eucalyptus plantations and benefiting from the expanding market for pulpwood. Therefore, on-farm experiments were conducted near Bhadrachalam, Khammam district (Andhra Pradesh) for over 4 years from August 2001 to November 2005 to examine whether wide-row planting and grouping of certain tree rows will facilitate extended intercropping without sacrificing wood yield. Eucalyptus planted in five-spatial arrangements in agroforestry [3 × 2 m (farmers’ practice), 6 × 1 m, 7 × 1.5 m paired rows (7 × 1.5 PR), 11 × 1 m paired rows (11 × 1 PR) and 10 × 1.5 m triple rows (10 × 1.5 TR)] was compared with sole tree stands at a constant density of 1,666 trees ha^?1. Cowpea (Vigna unguiculata) was intercropped during the post-rainy seasons from 2001 to 2004, and fodder grasses (Panicum maximum and Brachiaria ruziziensis) were intercropped during both the seasons of 2005. At 51 months after planting, different spatial arrangements did not significantly affect height and diameter at breast height (dbh). Total dry biomass of eucalyptus in different spatial arrangements ranged between 59.5 and 52.9 Mg ha^?1, the highest being with 6 × 1 m and the lowest with 10 × 1.5 TR, but treatment differences were not significant. The widely spaced paired row (11 × 1 PR) and triple row (10 × 1.5 TR) arrangements produced 62–73% of sole cowpea yield in 2003, 59–66% of sole cowpea yield in 2004, and 79–94% of sole fodder in 2005. In contrast, the 3 × 2 m spacing allowed only 17–45% of sole crop yields in these years. The better performance of intercrops in widely spaced eucalyptus was likely because of limited competition from trees for light and water. Intercropping of eucalyptus in these wider rows gave 14% greater net returns compared with intercropping in eucalyptus spaced at 3 × 2 m, 19% greater returns compared with that from sole tree woodlot and 263% greater returns compared with that from sole crops. Therefore, in regions where annual rainfall is around 1,000 mm and soils are fairly good, eucalyptus at a density of 1,666 plants per ha can be planted in uniformly spaced wide-rows (6 m) or paired rows at an inter-pair spacing of 7–11 m for improving intercrop performance without sacrificing wood production.     

遂宁市农村土壤重金属污染调查与评价

对遂宁市不同区域农村土壤中重金属污染状况进行了调查和分析,运用单项污染指数、内梅罗土壤综合污染指数以及富集因子法对其土壤质量进行了评价。结果表明:研究区Zn和Ni的质量分数平均值超过了四川省土壤重金属背景值,天宫村35%受Ni污染,15%受Zn污染,土壤重金属综合污染指数均大于1,为轻污染等级。平均内梅罗综合污染指数为0.78,尚清洁但处于警戒线。Zn有7个点位的富集因子处于1～1.5之间,Ni有17个点的富集因子大于1,受到了较强的人为污染与干扰。     

模拟CO2浓度升高对宁夏枸杞营养生长与果实品质的影响

【目的】研究宁夏枸杞对大气CO2浓度升高的生理生态响应机制,为探究枸杞及其他木本经济林植物在气候变化背景下优质高效栽培与育种提供理论依据。【方法】以‘宁杞1号’扦插苗为材料,采用开顶气室(open-top chamber,OTC)及自动监控系统模拟控制CO2浓度,测定宁夏枸杞在升高CO2浓度环境下植株营养生长指标与果实糖分含量、主要活性物质含量和蔗糖代谢相关酶活性的变化。【结果】 1) CO2浓度升高,促进宁夏枸杞植株生长发育,苗高增长量较对照分别高11.67%和18.65%,地径分别高55.09%和62.58%,新梢加长和加粗生长均呈增加趋势。2) 2种CO2浓度升高处理下,宁夏枸杞果实横径较对照分别增加4.56%和7.71%,单果质量分别增加15.05%和34.53%,果实更加饱满。3) CO2浓度升高处理下,夏果(处理90天左右)果实中果糖含量较对照略高,秋果(处理120天后)含量比对照分别低1.39%和3.98%。试验处理期间,果实中葡萄糖和总糖含量均低于对照,且CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理下降最为明显。夏果果实蔗糖含量均低于对照,秋果在CO2浓度升高1倍[(760±20)μmol·mol^-1 ]下较对照略高。4)果实中枸杞多糖含量低于对照,黄酮含量在秋果期比对照分别低16.62%和18.35%,且CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理对果实活性物质含量影响较大。5) CO2浓度升高增加了酸性转化酶和中性转化酶活性;夏果蔗糖磷酸合成酶较对照明显增加,但秋果酶活性低于对照;蔗糖合成酶分解方向与合成方向酶活性变化趋势相同,夏果均高于对照,秋果酶活性低于对照,CO2浓度升高1倍[(760±20)μmol·mol^-1 ]处理下差异极显著。【结论】长期高CO2浓度处理促进宁夏枸杞植株营养生长,果实单果质量与纵横径增大,有利于改善果实外观品质;但果实中糖分含量和枸杞多糖、黄酮等生物活性物质的含量明显降低,相关酶活性发生变化,影响果实营养品质。     

优良牧草引种试验初报

为寻求适合毛乌素沙区大力发展舍饲养殖业的优质高产主效牧草品种,探索农牧交错牧业 可持续发展的有效途径,特在红石峡沙地引进７种牧草进行试验。结果表明,所引牧草新品种完全适生于引种区的气候条件和土壤条件,其抗逆性强,并能获得较高的经济、生态和社会效益。建议在毛乌素沙区大力推广。     

马尾松硫酸盐浆两段氧脱木质素最佳工艺条件的研究

研究了马尾松硫酸浆两段氧脱木质素的最佳工艺条件。结果表明，第一段氧脱木质素的条件为：氧压0．6MPa，温度100℃，时间80min,NaOH 量5％，MgSO4用量0．5％，浆浓10％；第二段氧脱木质素的条件为：氧压0．4MPa，温度90℃，时间60min，NaOH用量3％，MgSO4用量0．5％，浆浓10％。在此条件下，OIOⅡ木质素脱除率达到72．5％，粘度775．2cm^3/g,得率90．5％。经过氧脱木质素后浆的裂断长5．8km，耐破指数5．3kPa.m^2/g，撕裂指数12．7mN.m^2/g。     

高层建筑框架结构安全隐患的预控

本文概述了高层建筑框架结构在施工图设计阶段几个方面的问题。避免因设计者的疏忽而给结构安全带来隐患。     

金镶玉竹对重金属铅镉的耐抗性

文章以盆栽金镶玉竹(Phyllostachys aureosulcata 'Spectabilis’)为试验材料,研究不同浓度铅、镉处理在金镶玉竹不同器官中的吸收、累积和迁移分配规律,以及铅、镉对金镶玉竹细胞膜透性、脂过氧化与抗氧化保护酶活性的影响。结果表明,在铅、镉胁迫下,根部是吸收积累重金属的最主要部位,重金属在不同器官之间的迁移分配表现出一定的差异;随着重金属处理浓度的增加,细胞质膜透性和膜脂过氧化程度增大,相对电导率和丙二醛(MDA)含量明显增加;胁迫初期抗氧化酶活性不断增加,随着胁迫时间的延长,酶活性不断下降。     

Diverging rationalities between forest fire management services and the general public after the 21st?century mega?fires in Greece

Wildfire risk related to hazards on people and assets is expected to increase in the face of climate change, especially in fire-prone environments such as the M...     

The receptivity of graft-polyacrolein on powdered beech wood (Fagus crenata) to hydroxylamine

Summary The receptivity of graft-polyacrolein on wood to hydroxylamine is discussed in terms of a geometric model for the voids and surfaces formed in wood by the swelling action of water. The receptivity of the carbonyl group of graft-polyacrolein varies inversely with the number of graft sites. This relationship is a consequence of decrease in the spacing between graft chains on the primary surface. The receptivity increases gradually with an increase in the amount of graft polymer, and this is a result of the swelling action of graft-polyacrolein which extends to the microscopically visible macropores of wood.