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1.
黄丘区野外草被坡面土壤入渗参数变化规律与模拟研究 总被引：1，自引：1，他引：0
利用黄丘区第三副区野外坡面模拟降雨试验,研究了3种覆盖度(30%,60%,90%)和5种降雨强度(1,1.5,2,2.5,3mm/min)下15°草地坡面土壤入渗过程变化规律。结果表明:(1)土壤入渗率随着草被覆盖度和降雨强度的增加不断增大,草被覆盖度越大,土壤入渗率的增加效果越显著,土壤初始入渗率与降雨强度呈指数函数关系,土壤稳定入渗率与降雨强度呈幂函数关系。(2)土壤累积入渗量与降雨时间呈良好的幂函数关系,草被覆盖度越大,土壤累积入渗增量越明显,降雨强度对土壤累积入渗量的影响存在阶段性差异。(3)草被覆盖度的增加能明显提高土壤入渗系数,随雨强的增大,土壤入渗系数不断减小,自然草被覆盖度(60%)下,草被增加土壤入渗系数的有效降雨强度为1~1.5mm/min。(4)利用4个入渗模型对土壤入渗速率与降雨时间的关系进行拟合,研究结果表明Horton公式能较好的模拟该区土壤入渗过程。 相似文献
2.
基于Hydrus-2D分析农田覆膜对降雨入渗的影响 总被引：1，自引：1，他引：0
为探究覆膜处理对农田降雨入渗过程的影响,该研究建立Hydrus-2D降雨入渗模型,模拟不同下垫面条件下不同覆膜和降雨情况对降雨入渗的影响。设裸地平作、无垄覆膜、起垄覆膜3种下垫面,覆膜宽度、降雨量和降雨历时3个因素,每个因素4个水平,共设置144种方案,模拟各方案的降雨入渗过程,分析其土壤含水率空间分布、湿润锋运移、雨后入渗量和有效降雨系数变化。结果表明,无垄覆膜、起垄覆膜处理雨后的膜间表层土壤含水率与裸地平作相比分别增加5.8%和9.2%,膜间水分入渗深度分别增加10.67和12.45 cm,说明覆膜和起垄均能促进降雨入渗;与裸地平作相比覆膜和起垄覆膜能显著提高有效降雨系数,特别是小降雨量的有效降雨系数增加明显;不同覆膜宽度对有效降雨系数的影响达到了显著水平,膜宽70 cm时有效降雨系数最大。因此通过调整覆盖地膜的宽度和设置垄沟可增加降雨入渗量及水分入渗深度,提高降雨资源和农田水分利用效率,这对缓解干旱半干旱区的农业缺水紧张情势,丰富农田水分运移、不同下垫面降雨入渗等相关理论具有重要作用。 相似文献
3.
黄土高原水土流失综合治理是以强化降雨入渗,减少地表径流,阻止土壤侵蚀为目的。因此,治理区降雨入渗量的大小是衡量水土流失治理效果的关键指标之一。目前入渗量的计算多利用年总降雨量,由于在黄土地区小雨量或小强度的降雨具有与水土流失治理的零相关性,因而会导致对水土流失综合治理强化入渗作用估计的较大误差。提出用1a中产生径流的次降雨总量(产流降雨总量)计算入渗量。以西川河流域为例,采用1997—2001年的降雨径流资料,分别用年降雨总量与产流降雨总量推求降雨入渗系数,对比分析了入渗量随流域水土流失治理度的变化,结果表明:利用产流降雨总量能比较清晰地反映流域治理程度对降雨入渗的影响。在此基础上,采用GM(1,1)灰色动态模型预测西川河流域降雨入渗量随水土流失治理度的变化趋势。结果表明,GM(1,1)灰色模型能够合理地预测黄土高原水土保持措施对自然流域入渗量影响的变化趋势。 相似文献
4.
《水土保持学报》2014,(6)
为揭示作物覆盖条件下坡耕地降雨入渗特征,以黄土高原3种典型秋作物(玉米、大豆和谷子)为对象,在3°~15°的坡地径流小区上,采用人工模拟降雨和水量平衡的方法,分析了作物全生育期降雨入渗过程中初始入渗率、稳定入渗率、平均入渗率和累积入渗量的数量特征及影响因素。结果表明:(1)作物坡地的降雨入渗过程随降雨历时的延长,入渗量呈由高到低的变化,波动性明显;(2)作物坡地的初始入渗率、平均入渗率和累积入渗量均高于裸坡地,而稳定入渗率除玉米坡地较大外,其余差异不大,4个参数值基本上与降雨强度和叶面积指数的增大成正比,与坡度成反比;(3)基于降雨强度、坡度及叶面积指数,通过多元回归分析建立了土壤初始入渗率、稳定入渗率、平均入渗率和累积入渗量多元回归模型,为入渗过程模拟提供了基础。 相似文献
5.
毛乌素沙地生物结皮对水分入渗和再分配的影响 总被引：4，自引：0，他引：4
生物结皮的发育影响着干旱半干旱区小尺度土壤水文过程。对两种自然降雨条件下（降雨量为8.5 mm和14.8 mm）的3种放牧管理类型（持续放牧地、围栏5 a禁牧区、围栏15 a禁牧区）有、无生物结皮土壤的降雨入渗速率和再分配规律进行了测定。结果如下：（1）入渗速率禁牧5 a和禁牧15 a样地的有结皮土壤的入渗速率极显著低于无生物结皮土壤。持续放牧样地上,生物结皮发育很差,其对土壤的入渗速率无显著影响。（2）入渗深度自然降雨为8.5mm的次日在持续放牧区能入渗到15～20 cm,而在禁牧5 a和禁牧15 a围栏区仅能入渗到10～15 cm。自然降雨为14.8 mm的次日在持续放牧区能入渗到30～40 cm,在禁牧5 a和禁牧15 a围栏区能入渗到20～25 cm。在无雨条件下,禁牧15 a围栏区50 cm以下土壤水分状况较禁牧5 a和持续放牧区更差。测定结果表明：生物结皮的形成降低了水分的入渗速率和自然降雨的下渗深度,使下渗水分减少,渗透深度变浅,由此可见当地高频率（84.6%）的小降雨（〈10mm）事件只能对浅根系的草本有效,这将使得草本植物生长旺盛而深根系半灌木油蒿生长不良,逐渐衰退。 相似文献
6.
《水土保持学报》2014,(3)
为探讨多种因素对麦田降雨入渗特征的影响及其相应的定量关系,通过人工模拟降雨试验,研究麦田降雨强度(RI)、冠层覆盖度(LAI)及0-40cm土层土壤初始含水量(θ40)对降雨入渗规律的影响。结果表明:其他影响因素一定条件下,入渗率和累积入渗量与降雨历时分别具有显著的幂函数和对数函数关系(P0.01);平均入渗率、稳定入渗率和入渗量随RI增大而增大,入渗率趋于稳定值的时间随RI增大而提前,降雨蓄积系数则随RI增大而减小;平均入渗率、稳定入渗率、入渗量和降雨蓄积系数随LAI增大而增大,入渗率趋于稳定值的时间则随LAI的增大而滞后,当降雨强度增大时,LAI对麦田入渗过程的影响减弱。在RI和LAI不变时,入渗率趋于稳定值的时间随θ40增大而提前,平均入渗率、入渗量和降雨蓄积系数随θ40增大而减小,但稳定入渗率基本相同。通过对模拟降雨实测数据统计分析,入渗率、累积入渗量可最终表示为t、RI、LAI和θ40的四因素函数关系,并建立降雨蓄积系数回归计算模型(P0.01)。 相似文献
7.
土壤 (特别是黄绵土 )在雨水作用下 ,表面会形成结皮 ,显著地降低降雨入渗率 ,聚丙烯酰胺 (PAM)能有效地抑制降雨过程中土壤结皮的形成 ,提高降雨入渗率。为了获得PAM使用量和覆盖率与入渗率之间的关系 ,进行了一系列的人工降雨模拟试验。试验采用了三个雨强 :5 0、1 0 0和 1 5 0mmh- 1,四个坡度 :8.74%、1 7.63 %、3 6.4%和 46.63 % ,及五种地表处理 :对照、秸秆覆盖和三个PAM覆盖率 (A、B和C) ,试验设三次重复。试验分Ⅰ、Ⅱ两个降雨阶段进行 ,第Ⅱ阶段在第Ⅰ阶段降雨结束土壤放置 2 4h后进行。分析建立了降雨入渗率与PAM的覆盖率间的相关关系 ,确定了PAM的覆盖率对降雨入渗的影响。 相似文献
8.
[目的]分析樟子松固沙林土壤水分动态对降雨入渗过程的响应,为深入研究沙地人工林土壤水分管理提供科学依据。[方法]采用Watchdog土壤水分自动监测系统测定了浑善达克沙地2个生长周期内沙地樟子松林和流动沙丘0—120cm土层水份含量的动态,并选择3种降雨事件探讨樟子松林土壤水分对降雨入渗的响应过程。[结果]在降雨量19.4mm时,樟子松林地降雨入渗到达20cm所需要时间为4h,而流动沙丘为5h;降雨量30.2mm时,樟子松林地降雨入渗到达40cm所需要时间为13h,而流动沙丘为9h;降雨量47.1mm时,樟子松林地降雨入渗到达80cm所需要时间为27h,而流动沙丘为24h。降雨19.4~47.1mm时樟子松林地降雨入渗深度可达80cm,而流动沙丘在降雨19.4mm时降雨入渗深度则超过80cm,降雨30.2mm或47.1mm时,降雨入渗深度则超过120cm。[结论]不同降雨事件对樟子松林不同土层降水入渗进程和降水入渗深度有明显影响。 相似文献
9.
为探讨自然降雨在黄土区干化土壤中的入渗性能,研究干化黄土的降雨入渗机制,在陕北米脂试验站,建立野外10 m大型土柱模拟枣林地深层干化土壤,利用CS650-CR1000土壤水分自动监测系统对2014-2019年的土壤水分状况进行了连续定位监测。结果表明:(1)日降雨量为33.6,35.6 mm的大雨(降雨强度分别为3.73,2.97 mm/h,降雨历时9.0,12.0 h)状况下,最大入渗深度为140,100 cm,累积入渗量达20.05,16.10 mm;日降雨量为19.0,16.8 mm的中雨(降雨强度分别为2.24,1.53 mm/h,降雨历时8.5,11.0 h)状况下,最大入渗深度为90,60 cm,累积入渗量达8.12,9.77 mm;日降雨量为9.6,8.8 mm的小雨(降雨强度分别为1.48,0.76 mm/h,降雨历时6.5,11.5 h)状况下,最大入渗深度为30,20 cm,累积入渗量仅为1.05,0.23 mm。(2)降雨入渗的湿润锋运移深度(Zi)随时间(T)呈幂函数Zi=aTb增加。(3)雨水的入渗历时包括降雨历时、自降雨停止至入渗结束两个时段。6次降雨(33.6,35.6,19.0,16.8,9.6,8.8 mm)在降雨停止后时段内的入渗深度分别为100,60,70,40,30,20 cm,入渗量依次为9.86,10.78,2.09,8.42,1.05,0.23 mm。在总入渗历时内,6次降雨入渗补给系数分别为0.60,0.45,0.43,0.58,0.11,0.03。黄土区降雨入渗深度受降雨量、降雨强度、入渗历时影响较大,提高单次降雨的雨量有助于提升雨水入渗补给系数,促进干化土壤得到有效水分修复。 相似文献
10.
为了对降雨入渗引起黄土斜坡土体含水率的变化有较深入的了解,在陕西省延安市宝塔山选取了一个典型的黄土自然斜坡进行土体含水率和降雨联合监测。监测结果表明,斜坡土体中的含水率对降雨入渗的响应具有时间上的滞后性与空间上的差异性。当日降雨量达到10mm或10d累计降雨量达到70mm时,降雨入渗对土体含水率的影响深度小于1.0m;当日降雨量达到50mm或10d累计降雨量达到140mm时,降雨入渗对土体含水率的影响深度小于2.0m。同时,当小时降雨量达到10.4mm时,降雨入渗至0.2m的入渗速率为0.04m/h,由0.2m入渗至1.0m的入渗速率为0.033m/h,降雨入渗速率随着土层深度的增加而减小。 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.
Kyle Devey Michael Mucalo Gordon Rajendram Joseph Lane 《Communications in Soil Science and Plant Analysis》2015,46(4):72-80
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.
I.L. Boyd 《Biological conservation》2010,143(7):1664-1674
“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
14.
Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage 总被引：1，自引：0，他引：1
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
15.
《中国生态农业学报》2014,(8)
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
16.
M.A. Callaham Jr. J.M. BlairT.C. Todd D.J. KitchenM.R. Whiles 《Soil biology & biochemistry》2003,35(8):1079-1093
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.
Yoav Bashan Bernardo Salazar Ma. Esther Puente Macario Bacilio Robert Linderman 《Biology and Fertility of Soils》2009,45(6):585-594
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
18.
Grete Skrede Berit Karoline Martinsen Anne-Berit Wold Stein-Erik Birkeland Kjersti Aaby 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):193-208
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
19.
Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value. 相似文献
20.
Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation. 相似文献