Effect of Ploughing Depth on the Growth and Yield of Heracleum candicans： a Threatened Medicinal Herb and a Less-explored Potential Crop of the Himalayan Region     

Hemant K. Badola Jitendra S. Butola 《山地科学学报》2005,2(2):173-180

This paper examines the effect of ploughing depths （A -- 60 cm, B -- 45 cm and C -- 30 cm） on the growth and yield of Heracleum candicans Wall （Apiaceae）, a threatened medicinal herb of the Himalayan region. This less-explored plant is being suggested as a potential crop for the mountain agriculture. The study was carried out in an orchard in Himachal Pradesh, India at 2500 m altitude, for two successive growth years. During the first year, all plants remained in juvenile state; in the second year, nearly 65 % plants produced flowers only under 60cm ploughing depth. Among its morphological traits, plant height, collar diameter and aboveground flesh weight were found to be strongly correlated （P 〈 0.01） with the belowground biomass during the first year （r =0.968, 0.925 and 0.973, respectively） and during the second year （r=0.945, 0.928 and 0.775, respectively）. Increase in the ploughing depth was significantly correlated （P〈0.01） with all growth parameters, including the belowground dry weight, marketable portion of the produce. The belowground biomass （commercial yield; 16.28 Qt/hec） at depth A was about 2.6 and 4.7 times higher than those recorded at depths B and C, respectively. The results clearly justify the importance of deep ploughing and this paper strongly recommends it for economically sustainable cropping.  相似文献   

AREAL DIFFERENTIATION AND CONSTRUCTION OF OASIS AGRICULTURAL ECOSYSTEM IN THE SHIYANG RIVER BASIN     

张维祥  梁智睿 《中国地理科学(英文版)》1993,3(4):357-364

On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic benefits, production efficiency, ecological stabilities and developmental conditions of the Wuwei Oasis agricultural ecosystem in the middle reaches of the river basin and the Minqin Oasis agricultural ecosystem in the lower reaches. Under a same management level and investment of . material and energy, primary productiveness and economic benefits of the former are higher than those of the latter. Construction directions of Wuwei and Minqin oases should be different in order to alleviate the water- use contradiction between the middle and lower reaches. The construction objective of Wuwei Oasis should be efficient irrigated farming production system and Minqin Oasis should become a mixed forestry-pastoral-farming ecosystem taking ecological protection as its major function.  相似文献   

Experimental constraints on the effects of pressure and H2O on the fractional crystallization of high-Mg island arc basalt     

Morihisa Hamada  Toshitsugu Fujii 《Contributions to Mineralogy and Petrology》2008,155(6):767-790

H₂O-undersaturated melting experiments of synthesized basalt (SiO₂ = 50.7 wt.%, MgO = 8.3 wt.%, Mg# = 60) were conducted at fO₂ corresponding to NNO+1 and NNO−1 to clarify the effects of pressure (2–7 kbar) and H₂O on fractional crystallization in island arcs. H₂O content was ranged from nominally anhydrous to 4.4 wt.%. Differentiation trends, namely the liquid lines of descent, change sensitively according to pressure-H₂O relations. Tholeiitic differentiation trends are reproduced with H₂O ≤ ∼2 wt.% in primary magma. With such quantities of H₂O, fractional crystallization is controlled by olivine + plagioclase at 2 kbar. Increasing the pressure from 2 to ≥4 kbar induces early crystallization of orthopyroxene instead of olivine and therefore SiO₂ enrichment in the residual melts is suppressed. Increasing H₂O (≥ ∼2 wt.% in primary magma) stabilizes clinopyroxene relative to orthopyroxene and/or magnetite. Although the phase relations and proportions strongly depend on fO₂ and H₂O content, differentiation trends are always calc-alkaline.  相似文献   

Global Correlations of Ocean Ridge Basalt Chemistry with Axial Depth: a New Perspective   总被引：4，自引：0，他引：4  

Niu  Yaoling; O'Hara  Michael J. 《Journal of Petrology》2008,49(4):633-664

The petrological parameters Na₈ and Fe₈, which are Na₂O andFeO contents in mid-ocean ridge basalt (MORB) melts correctedfor fractionation effects to MgO = 8 wt%, have been widely usedas indicators of the extent and pressure of mantle melting beneathocean ridges. We find that these parameters are unreliable.Fe₈ is used to compute the mantle solidus depth (P_o) and temperature(T_o), and it is the values and range of Fe₈ that have led tothe notion that mantle potential temperature variation of T_P= 250 K is required to explain the global ocean ridge systematics.This interpreted T_P = 250 K range applies to ocean ridges awayfrom ‘hotspots’. We find no convincing evidencethat calculated values for P_o, T_o, and T_P using Fe₈ have anysignificance. We correct for fractionation effect to Mg^# = 0·72,which reveals mostly signals of mantle processes because meltswith Mg^# = 0·72 are in equilibrium with mantle olivineof Fo_89·6 (vs evolved olivine of Fo_{88·1–79·6}in equilibrium with melts of Fe₈). To reveal first-order MORBchemical systematics as a function of ridge axial depth, weaverage out possible effects of spreading rate variation, local-scalemantle source heterogeneity, melting region geometry variation,and dynamic topography on regional and segment scales by usingactual sample depths, regardless of geographical location, withineach of 22 ridge depth intervals of 250 m on a global scale.These depth-interval averages give Fe₇₂ = 7·5–8·5,which would give T_P = 41 K (vs 250 K based on Fe₈) beneathglobal ocean ridges. The lack of Fe₇₂–Si₇₂ and Si₇₂–ridgedepth correlations provides no evidence that MORB melts preservepressure signatures as a function of ridge axial depth. We thusfind no convincing evidence for T_P > 50 K beneath globalocean ridges. The averages have also revealed significantcorrelations of MORB chemistry (e.g. Ti₇₂, Al₇₂, Fe₇₂,Mg₇₂, Ca₇₂, Na₇₂ and Ca₇₂/Al₇₂) with ridge axial depth. Thechemistry–depth correlation points to an intrinsic linkbetween the two. That is, the 5 km global ridge axial reliefand MORB chemistry both result from a common cause: subsolidusmantle compositional variation (vs T_P), which determines themineralogy, lithology and density variations that (1) isostaticallycompensate the 5 km ocean ridge relief and (2) determine thefirst-order MORB compositional variation on a global scale.A progressively more enriched (or less depleted) fertileperidotite source (i.e. high Al₂O₃ and Na₂O, and low CaO/Al₂O₃)beneath deep ridges ensures a greater amount of modal garnet(high Al₂O₃) and higher jadeite/diopside ratios in clinopyroxene(high Na₂O and Al₂O₃, and lower CaO), making a denser mantle,and thus deeper ridges. The dense fertile mantle beneath deepridges retards the rate and restricts the amplitude of the upwelling,reduces the rate and extent of decompression melting, givesway to conductive cooling to a deep level, forces melting tostop at such a deep level, leads to a short melting column,and thus produces less melt and probably a thin magmatic crustrelative to the less dense (more refractory) fertile mantlebeneath shallow ridges. Compositions of primitive MORB meltsresult from the combination of two different, but geneticallyrelated processes: (1) mantle source inheritance and (2) meltingprocess enhancement. The subsolidus mantle compositional variationneeded to explain MORB chemistry and ridge axial depth variationrequires a deep isostatic compensation depth, probably in thetransition zone. Therefore, although ocean ridges are of shalloworigin, their working is largely controlled by deep processesas well as the effect of plate spreading rate variation at shallowlevels. KEY WORDS: mid-ocean ridges; mantle melting; magma differentiation; petrogenesis; MORB chemistry variation; ridge depth variation; global correlations; mantle compositional variation; mantle source density variation; mantle potential temperature variation; isostatic compensation  相似文献   

弧后盆地的形成与演化探讨：以东亚陆缘区为例   总被引：3，自引：2，他引：3  

吴有林  林舸 《海洋地质与第四纪地质》1996,16(4):63-69

通过对弧后盆地大地构造体制的讨论，作者认为基属活化作用的产物根据地质，地球物理，地球化学等资料的分析，作者提出结论认为，由于东亚岛弧系岩石圈的均衡作用及海沟外侧冷却大洋岩石圈块体的下沉拖曳牵引等作用，使软流圈在岛弧系下方发生分异，这种分异作用带动东亚陆缘向东扩张，从而产生弧后的张开。  相似文献   

Population structure of Haliotis rubra from South Australia inferred from nuclear and mtDNA analyses   总被引：1，自引：0，他引：1  

LI Zhongbao  Sharon A Appleyar  Nicholas G Elliott 《海洋学报(英文版)》2006,25(4):99-112

1Introduction ThemajorityofAustralia’sabalonefisheryex ports(5.135kt,worth＄216millionin2002～2003,ABARE2004)consistofblacklipabalone(HaliotisrubraLeach,1814).AssuchH.rubrais consideredasanimportantmarineresourcewithin Australia.Likemanyabalonespecieswor…  相似文献   

温度对金红色大鳞副泥鳅(Paramisgurnus dabryanus)孵化、仔鱼活力和性别分化的影响     

马本贺  王海华  马爱军  黄智慧  李燕华  王梦杰  孙志宾 《海洋与湖沼》2022,53(2):448-456

以大鳞副泥鳅(Paramisgurnus dabryanus)新品系“赣红1号”为对象,探究了不同温度(20,23,26,29,32℃)对其受精卵孵化、仔鱼活力和性别分化的影响。结果显示,当温度在20~32℃范围内时,培育周期和孵化周期与温度均呈负相关关系,均随着温度的升高而缩短。培育周期在各温度组间差异显著(P<0.05),孵化周期在29和32℃组间差异不显著,其余各组间均具有显著差异(P<0.05)。随着温度的升高,孵化率先升高后降低,26℃时孵化率达到最高;畸形率呈现与孵化率相反的趋势,26℃时畸形率最低,且显著低于20、29和32℃组(P<0.05);仔鱼的不投饵存活系数(SAI)随着温度的升高而逐渐降低,各组间差异显著(P<0.05),23℃时SAI值为59.77,最大可存活时间为15日龄;此外,雄性率随温度的升高而增加,高温可促进个体趋向雄性发育。研究发现“赣红1号”受精卵孵化、仔鱼活力和性别分化均受到温度的重要影响,结合生产实际和试验数据,其孵化和仔鱼培育的适宜温度应保持在23~26℃。  相似文献   

Modelling morphological processes in the vicinity of shore-parallel breakwaters     

Julio A. Zyserman  Hakeem K. Johnson 《Coastal Engineering》2002,45(3-4)

  相似文献   

南海毛蚶形态特征对体重的相关分析   总被引：11，自引：0，他引：11  

王辉  刘志刚  符世伟 《热带海洋学报》2007,26(6):58-61

随机选取同龄南海毛蚶Scapharca subcrenata雌性62只、雄性59只,测量壳长、壳厚、壳高、后闭壳肌直径、放射肋数及活体重。采用通径分析方法研究南海毛蚶5个形态特征对体重的总效应,并以综合决定系数为确定形态性状重要性的准则。结果表明,两性中壳厚、壳高和壳长与体重均为正相关(p<0.01),直接和间接途径都不是体重的限制因素。壳厚、壳高的平均综合决定系数分别为0.423和0.412,是影响体重最主要因素且都具有育种意义。  相似文献   

Cyclicity in the Main and Upper Zones of the Bushveld Complex, South Africa: Crystallization from a Zoned Magma Sheet   总被引：9，自引：0，他引：9  

TEGNER  CHRISTIAN; CAWTHORN  R. GRANT; KRUGER  F. JOHAN 《Journal of Petrology》2006,47(11):2257-2279

The major element composition of plagioclase, pyroxene, olivine,and magnetite, and whole-rock ⁸⁷Sr/⁸⁶Sr data are presented forthe uppermost 2·1 km of the layered mafic rocks (upperMain Zone and Upper Zone) at Bierkraal in the western BushveldComplex. Initial ⁸⁷Sr/⁸⁶Sr ratios are near-constant (0·7073± 0·0001) for 24 samples and imply crystallizationfrom a homogeneous magma sheet without major magma rechargeor assimilation. The 2125 m thick section investigated in drillcore comprises 26 magnetitite and six nelsonite (magnetite–ilmenite–apatite)layers and changes up-section from gabbronorite (An₇₂ plagioclase;Mg# 74 clinopyroxene) to magnetite–ilmenite–apatite–fayaliteferrodiorite (An₄₃; Mg# 5 clinopyroxene; Fo₁ olivine). The overallfractionation trend is, however, interrupted by reversals characterizedby higher An% of plagioclase, higher Mg# of pyroxene and olivine,and higher V₂O₅ of magnetite. In the upper half of the successionthere is also the intermittent presence of cumulus olivine andapatite. These reversals in normal fractionation trends definethe bases of at least nine major cycles. We have calculateda plausible composition for the magma from which this entiresuccession formed. Forward fractional crystallization modelingof this composition predicts an initial increase in total iron,near-constant SiO₂ and an increasing density of the residualmagma before magnetite crystallizes. After magnetite beginsto crystallize the residual magma shows a near-constant totaliron, an increase in SiO₂ and decrease in density. We explainthe observed cyclicity by bottom crystallization. Initiallymagma stratification developed during crystallization of thebasal gabbronorites. Once magnetite began to crystallize, periodicdensity inversion led to mixing with the overlying magma layer,producing mineralogical breaks between fractionation cycles.The magnetitite and nelsonite layers mainly occur within fractionationcycles, not at their bases. In at least two cases, crystallizationof thick magnetitite layers may have lowered the density ofthe basal layer of melt dramatically, and triggered the proposeddensity inversion, resulting in close, but not perfect, coincidenceof mineralogical breaks and packages of magnetitite layers. KEY WORDS: layered intrusion; mineral chemistry; isotopes; magma; convection; differentiation  相似文献