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1.
针对食葵机械化收获水平低、损失大、含杂率高及籽粒破损严重等现状,该研究根据成熟期食葵生物特性,在传统联合收获机结构基础上设计一种4KHZ-330型食葵联合收获机,在割台上增设脱粒装置实现葵盘在割台上脱分,可有效缩短葵盘输送路径,提高清选质量。首先阐述食葵联合收获机的总体设计方案及动力传动模式,并对割脱一体式割台、割台升降机构、清选装置及气力输送装置等关键部件进行设计,确定相关参数。机具配套动力113 kW,工作幅宽为3300 mm,可一次完成食葵切割、脱粒、输送、清选、集籽、集草及卸载等工序。田间试验表明,收获机在低、中、高3种工作档位下,总损失率均低于4.0%,籽粒含杂率均低于5.0%,籽粒破损率均低于2.0%,生产率为0.40～0.85 hm2/h,作业性能指标满足食葵机械化收获标准。作业过程中收获机各关键部件之间运动协调关系平稳,食葵喂入顺畅,工作效率高,可以作为食葵联合收获机使用。  相似文献   

2.
4LZZ-1.0型小区稻麦联合收割机的研制及试验   总被引：1，自引：1，他引：0  
针对中国田间育种机械化程度低、缺乏小区育种作业装备的现状,结合国内小区稻麦种植模式和农艺要求,研制出了4LZZ-1.0型小区稻麦联合收割机。对机器整体设计方案进行了描述,并对气力辅助割台装置、脱粒装置、清选装置、气力输送装置等进行了设计,确定其关键参数。该装备采用静液压轮行走装置和全喂入收获方式,可一次完成育种小区稻麦的分禾、扶禾、切割、喂入、脱粒、清选、清种、份量装袋等工序。样机田间小区收获试验表明,该样机作业性能稳定,生产率39.4小区（4.7 m×2.7 m）/h、脱净率99.97%、含杂率1.46%、破碎率0.04%、损失率1%、小区时隔50.94s、混种率0,各项性能指标均达到或超过了设计指标和相关标准。  相似文献   

3.
履带式丘陵山地胡麻联合收割机设计与试验   总被引：1，自引：1，他引：0  
针对丘陵山区地块面积小、道路狭窄,大型联合收割机运输难、进地难、转场难、操作难等现状,解决胡麻茎秆易缠绕、易堵塞、难喂入等问题,该研究设计了一种履带式丘陵山地胡麻联合收割机。该机采用防缠绕低损割台、纹杆+杆齿组合式小锥度横轴流脱粒滚筒、组合式窄栅格凹板等结构,可实现胡麻茎秆的防缠绕快速喂入、分段式脱粒与分离、清选等作业。试验结果表明:胡麻籽粒含水率为5.42%时,脱净率为98.76%、含杂率3.61%、破损率0.18%、割台损失率1.07%、夹带损失率0.25%,清选损失率0.81%、飞溅损失率0.26%、总损失率2.36%。作业期间整机运行平稳,作业指标符合胡麻机械化收获标准,满足胡麻机械化收获要求,可以作为丘陵山地胡麻联合收割机使用。  相似文献   

4.
4DL-5A型蚕豆联合收割机关键部件设计与优化   总被引：2，自引：2，他引：0  
针对国内蚕豆机械化收获作业中存在的含杂多、损失大、破碎高等难题,该研究对集切割、输送、脱粒、清选、收集于一体的蚕豆联合收割机的关键部件进行设计。首先对4DL-5A型蚕豆联合收割机关键部件进行设计与分析,确定割台装置、脱粒装置、清选装置主要工作参数,然后采用二次正交旋转组合试验方法设计试验并用Design-Expert进行数据处理,以含杂率、损失率、破碎率作为响应指标,重点研究4DL-5A型蚕豆联合收割机收获作业中前进速度、滚筒转速和风机转速对响应指标的影响规律,建立含杂率、损失率和破碎率的回归数学模型,通过响应曲面方法分析各因素交互作用影响,对回归模型进行多目标优化,得出4DL-5A型蚕豆联合收割机作业参数的最优组合为：前进速度0.57 m/s,滚筒转速400.45 r/min,风机转速1265.16 r/min,此时,含杂率3.23 %,损失率3.00 %,破碎率2.72 %。对优化参数进行田间试验验证,测得含杂率3.49 %,损失率2.87 %,破碎率2.83 %,与优化值相对误差分别为8.05 %、4.33 %、4.04 %,结果较吻合。该研究结果可为蚕豆联合收割机设计、结构改进和作业参数调整提供参考。  相似文献   

5.
双通道喂入式再生稻收获机研制   总被引：3，自引：1，他引：2  
针对再生稻的头季稻机械化收获和低碾压率收获需要,该文设计了一种双通道喂入式再生稻收割机,主要由履带式底盘、割台、2套左右对称布置的脱粒清选装置和秸秆粉碎器、粮箱及动力与传动系统等组成。基于再生稻头季稻机械收获稻茬碾压模型确定其割幅为3000 mm,底盘轨距1500 mm,履带宽度400 mm,履带接地长度1800 mm。对双通道割台、秸秆粉碎器等关键部件进行设计分析,确定搅龙中部2个螺旋叶片起始位置的周向夹角为180°、秸秆粉碎器排草尾板外侧板倾角为8.2°、内侧板倾角为6°、上盖板与垂直方向夹角为63°。田间试验结果表明:该机作业速度可达0.8 m/s,喂入量4.6 kg/s,总损失率2.1%,含杂率0.4%,破碎率0.2%。直行碾压率26.7%,作业性能稳定,作业过程顺畅,尾部秸秆粉碎器可将碎秸导入履带碾压区。与现有常规收割机相比,该机可使再生稻头季稻的直行碾压率降低16.2%,可使再生季每公顷增产23.9%。该研究可为长江中下游地区再生稻机械化收获技术与装备研究及推广提供参考。  相似文献   

6.
纵轴流联合收获机关键部件改进设计与试验   总被引：4，自引：3，他引：1  
针对当前履带式纵轴流联合收获机中存在的工作状态无法在收获不同作物间快速转换,割台损失率较高、脱粒分离能力较差以及功耗高等不足,对割台、脱粒、清选、行走等主要工作部件进行了改进设计与试验研究。将割台设计为无级调速可伸缩式结构,脱粒装置改为纵轴同径差速滚筒脱粒装置,采用单HST(hydro static transmission)原地转向行走装置及防粘附清选装置,并经室内试验和田间试验表明:可伸缩割台能实现稻麦收割状态与油菜收割状态的快速转换,扩大了割台的使用功能,收获油菜损失显著减少,与常规相比较,油菜损失率降低2.8个百分点;差速轴流滚筒提高了脱粒效果和分离能力,与等长度单转速轴流滚筒相比,夹带与脱不净损失率分别减少了0.02个百分点与0.09个百分点,破碎率减少了0.017个百分点;原地转向行走机构减少了地表土壤的破坏并降低了转向功耗,以原地转向替代单边制动转向时,节约功耗37.0%;清选机构抖动板和清选筛面经不沾水处理,改善了潮湿谷物的清选性能,清选损失率降低0.9个百分点,含杂率降低0.4个百分点;这些联合收获机主要工作部件的改进设计提高了整机工作性能,以期为联合收获机主要工作部件改进,提高联合收获机工作性能提供参考。  相似文献   

7.
为实现国内大豆大田生产低损收获同时兼顾大豆育种小区收获,该研究设计了4LZ-1.5型大豆联合收获机,针对大豆成熟期易炸荚的特性,分析了大豆拨禾作业过程,建立了拨禾轮结构和运动参数求解模型,并对拨禾轮半径、拨禾速度比、拨禾轮转速等参数进行优化;针对大豆结荚低、收割易铲土的特性,分析了大豆籽粒尺寸参数统计规律,并对割台除土机构进行优化;针对大豆成熟期易脱粒、易破碎特性,对脱粒分离装置、清选装置和气力卸粮装置进行优化;针对育种小区收获要求,建立了清种装置曲柄摇杆机构数字化设计模型,确定了清种装置结构参数。分别进行大田生产和育种小区收获试验,结果表明,大豆大田生产收获的损失率<3.5%,破碎率<1.5%,含杂率<1%;大豆育种小区收获的损失率<3%,破碎率<1.5%,含杂率<1%,混种率<0.2%,清种时间200～270 s,满足大豆大田生产和育种小区收获作业要求。与现有大豆收获机械相比,4LZ-1.5型大豆联合收获机收获损失率降低1.5%～5%、破碎率降低3.5%～6.5%、含杂率降低2%～7%,研究结果可为后续大豆收获机结构改进和作业参数优化提供参考。  相似文献   

8.
小麦联合收获机双出风口多风道清选作业试验   总被引：4，自引：4，他引：0  
针对小麦联合收获机双出风口多风道清选装置由于主要作业参数调整不当而导致清选损失率、含杂率、二次含杂率高的问题,该文通过台架试验分别对双出风口多风道清选装置主要作业参数(喂入量、风门开度、风机转速、上、下导风板角度)进行单因素与多因素优化试验,探究各试验因素对清选损失率、含杂率、二次含杂率的影响规律,寻找最优参数组合。参考市场上小麦收获机拥有量较大的久保田988机型相关参数,搭建联合收获机双出风口多风道试验台。双出风口4风道时,小麦清选损失率、含杂率最低,分别为0.78%与0.48%,通过单因素试验,得出喂入量4.5～5.8 kg/s、风门开度0°～20°、风机转速1 200～1 600 r/min、上、下导风板角度0～20°。利用Box-Behnken中心组合试验设计理论,进行五因素三水平正交试验。结果表明:对清选损失率影响较显著的因素有风机转速、喂入量、上导风板角度;对含杂率影响较显著的因素有风机转速、上、下导风板角度;对二次含杂率影响较大的因素有上导风板角度、风机转速、喂入量,通过对目标参数优化得到最优作业参数为喂入量4.5 kg/s、风门开度10.2°、风机转速1 548 r/min、上、下导风板角度分别为20°和0°,此时清选损失率、含杂率、二次含杂率分别为0.79%、0.40%与0.82%。台架试验验证得到清选损失率、含杂率、二次含杂率分别为0.75%、0.38%与0.76%,与优化结果误差分别为5.1%、5.0%与7.3%。此研究结果可为小麦联合收获机多风道清选装置作业参数调整提供理论参考。  相似文献   

9.
履带式稻麦联合收获机田间收获工况下振动测试与分析   总被引：8，自引：7，他引：1  
为研究履带式全喂入联合收获机田间收获时的振动特性以及不同喂入量下的振动特性,以沃得锐龙4LZ-5.0E履带式全喂入稻麦联合收获机为研究对象,利用DH5902动态信号测试分析系统对不同喂入量收获工况下整机12个测点处的振动进行了测试与分析,结果表明振动筛、脱粒滚筒、发动机分别是机器前后、左右、上下方向上的主要激振源,但作物喂入割台和输送槽组成的腔体结构后,吸收了部分振动,使得割台和输送槽测点处的振动总量分别下降了25%、39%;与无作物喂入相比,喂入量为2.44 kg/s时输送槽驱动轴和脱粒滚筒测点处的振动分别增大了90%和149%,而喂入量增大到3.87 kg/s时振动总量却下降了15%左右,因此收获时应使机器保持一定的喂入量,可以降低整机振动;驾驶座椅支座、发动机机脚支座和底盘机架上测点处的振动均与作物喂入量呈正相关性。研究结果可为降低履带式联合收获机田间收获工况下整机振动,进而提高其驾驶舒适性提供参考。  相似文献   

10.
4HQL-2型全喂入花生联合收获机的研制   总被引：13，自引：11，他引：2  
针对中国花生的种植特点,借鉴已有的设计经验,研制成功了一种适于中国花生主产区收获作业的4HQL-2型全喂入花生联合收获机。该机利用挖拔组合式工作原理,为保证挖拔效果和稳定性,设计了一种全新的挖拔组合装置;夹持输送部件首次采用了三带夹持原理（普通V型带）,利用柔性夹持方式大大降低了花生的机械掉果率;去土部件采用了上下摆拍式去土方式,去土效果好,损失低;摘果装置采用全喂入式,利用甩捋式工作原理提高了鲜湿花生的摘净率;清选装置采用风筛组合式,逐稿器和振动筛作反向摆动可有效地减轻整机振动。经田间检测摘果率为99.6%,总损失率3.3%,破损率2.0%,含杂率2.2%,达到了设计和相关标准要求,并已通过农业部鉴定。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引：2，自引：2，他引：0  
【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。  相似文献   

12.
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.  相似文献   

13.
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,  相似文献   

14.
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.  相似文献   

15.
Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.  相似文献   

16.
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.  相似文献   

17.
Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.  相似文献   

18.
Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L?1 nitric acid (HNO3) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L?1 ammonium acetate (NH4OAc) and 1.0 mol L?1 HNO3 extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.  相似文献   

19.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

20.
To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.  相似文献   

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