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1.
黑龙江省黑土区水土流失动态及成因分析 总被引：2，自引：0，他引：2
为了解不同时期黑龙江省黑土区水土流失状况及其演变动态,根据历史调查资料、小流域原位勘察结果及同期遥感调查数据,分别对1950,1980和2000年黑龙江省黑土区50a来不同空间尺度水土流失状况、特征、成因及演变进行分析。结果表明:(1)该区水土流失面积50a来净增了2.08×104 km2,水蚀是造成该区水土流失主要形式。(2)1950-1980年20a间年均水土流失面积为411.9km2,比1980-2000年年均值高出25.5km2。(3)50a来该区侵蚀沟数量增加98 832条,2000年侵蚀沟面积所占比例比1950年增加了172.4%,沟壑密度增加2.83倍。该区水土流失呈持续恶化态势,不合理人类活动、政策导向和黑土质量退化是导致该区水土流失程度动态变异主要诱因。 相似文献
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黑土坡面细沟形态及剖面特征试验研究 总被引：3，自引：0，他引：3
[目的] 对比分析不同坡度条件下黑土坡面细沟宽度、深度、宽深比、细沟剖面形态及沟壁坡度特征，为东北黑土区坡耕地细沟侵蚀防治提供科学参考。[方法] 在野外径流小区不同坡度（5°和10°）下开展汇流冲刷试验〔1 L/（min·m2），历时60 min〕。[结果] ①试验条件下，黑土坡面细沟剖面形态主要为“U”型，细沟平均宽深比介于2.3~4.9之间；②随着坡度的增大，细沟下切侵蚀作用增强幅度明显超过细沟沟壁崩塌侵蚀作用，导致细沟宽深比减小，细沟剖面形态由“宽浅型”向“窄深型”转化；③对于坡面不同位置，细沟平均宽深比在坡上，坡中，坡下位置分别为2.7，1.6，5.4，即自坡面上部到下部依次表现为“宽浅型”—“窄深型”—“宽浅型”的细沟剖面变化特征；④黑土坡面细沟沟壁坡度主要为37.7°~85.2°，其值随着地面坡度的增加而增大，且不同坡位之间细沟沟壁坡度表现为坡中位置大于坡上和坡下位置。[结论] 防治东北黑土区陡坡耕地中段位置的细沟发育尤为重要，对缓解该区水土流失问题有重要作用。 相似文献
3.
[目的] 分析渭河源区不同等级坡耕地的时空变化,揭示不同坡耕地类型的土壤保持效应,探讨退耕还林还草工程对渭河源区坡耕地及土壤保持的影响,为完善不同坡耕地资源合理规划利用提供科学依据。[方法] 利用1990,2000,2010和2020年4期渭河源区土地利用和地形数据,通过叠加分析、耕地动态度、土地利用转移矩阵和中国土壤流失方程等方法进行分析。[结果] ①1990—2020年耕地呈先缓慢增加后急剧减少再缓慢减少的趋势,面积净减少321.03 km2,其中陡坡耕地和缓坡耕地是耕地变化主要类型。②近30 a来,耕地的时空变化主要表现为1990—2000年耕地少量转入,主要分布在漳县和岷县;随着退耕还林还草工程的实施,有279.80 km2的坡耕地转变为林草地,其中耕地转换为草地主要分布在通渭和陇西县,而耕地转换为林地主要分布在陇西和岷县。③1990—2000年渭河源区林草地开垦导致土壤保持量减少5.52×104 t,而2000—2020年退耕还林还草导致土壤保持量增加2.21×106 t,其中大于15°的坡耕地的转变对土壤保持量变化影响更大。[结论] 渭河源区退耕还林还草工程成效显著,其中2000—2010年陡坡耕地的退耕面积最大,陡坡耕地退耕地土壤保持总体效应最大,但峭坡耕地退耕地单位效应最大。峭坡耕地仍有较大退耕空间,依旧是新一轮退耕任务的主要目标。 相似文献
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5.
植被覆盖和降雨因子变化及对东北黑土区土壤侵蚀的影响 总被引：1，自引：0，他引：1
[目的] 研究东北黑土区植被覆盖和降雨侵蚀力因子对土壤侵蚀时空变化的影响程度,为该区水土流失治理和可持续发展提供科学依据。[方法] 运用修正后的通用土壤流失方程（RUSLE）得到了2000—2018年东北黑土区土壤侵蚀分布特征,并探究土壤侵蚀模数与因子时空分布变化规律,得出侵蚀模数对于植被覆盖和降雨侵蚀力因子变化的敏感性。[结果] 黑土区土壤侵蚀变化与植被覆盖与管理因子和降雨侵蚀力因子的变化相关。研究期间侵蚀模数从1 175.20 t/（km2·a）下降至822.07 t/（km2·a）,并且全区主要以微度侵蚀和轻度侵蚀为主,空间上呈现西南向东北逐渐降低的空间分布特点。[结论] 东北黑土区东南部和西南部的植被覆盖与管理因子（C）敏感系数分别为0.95和1.00,是强度敏感区域,提高植被覆盖度将成为有效治理手段;西北与西南降雨侵蚀力因子（R）敏感系数分别为0.45和1.00,为中度敏感和强度敏感的区域,降低降雨的影响对治理侵蚀最为有效。 相似文献
6.
漫川漫岗黑土区水土流失综合治理范式 总被引：2，自引：0，他引：2
漫川漫岗黑土区是我国东北商品粮主产区和黑土坡耕地最集中的地方,也是坡耕地水土流失最严重的地区。根据漫川漫岗黑土区水土流失规律和特点,在已有水土流失治理模式的基础上,通过总结该区水土流失综合调控机制,凝练基于粮食安全的黑土区长坡缓坡水土流失综合治理范式,并对形成的水土流失综合治理范式体系的结构进行解析,对其推广应用效益进行分析,以补充和完善黑土区水土流失综合调控理论。结果表明:1)漫川漫岗黑土区水土流失治理应以坡耕地水土流失控制为主,水土流失综合治理调控主要由地表径流调控、沟道侵蚀调控和土地生产力调控3部分构成;2)基于粮食安全的黑土区长坡缓坡水土流失综合治理范式,以生态安全保障和粮食安全保障2大体系为支撑,系统结构主要包括水土流失立体防护体系结构和生态农业技术体系结构及二者之间的耦合;3)该范式可为促进东北漫川漫岗黑土区生态、社会和经济更协调发展提供科学参考和实践样板。 相似文献
7.
[目的] 探索坡式条田在黑土区坡耕地水土保持和改善土壤环境中的作用，以期为坡式条田在坡耕地上的利用提供理论支持。[方法] 基于野外试验，观测研究了坡式条田对径流产沙、土壤水热和土壤呼吸的影响。[结果] ①黑土坡面设置坡式条田具有良好的减流减沙效果，年均减少输沙率和减少地表径流率分别为78.3%和68.5%，土壤侵蚀模数为87.53 t/（km2·a），控制在允许范围内；②修筑坡式条田显著提高土壤质量含水量（p<0.05），并能显著增加植被覆盖度（p<0.01）；③研究区土壤呼吸与土壤温度显著相关，修筑坡式条田能够显著降低土壤呼吸速率，降低土壤碳素损失。[结论] 黑土区坡式条田能够很好地防治水土流失，改善土壤水热和植被状况，且能降低土壤呼吸造成的C素流失，应在黑土坡耕地上推广应用。 相似文献
8.
基于RUSLE的蔗区小流域土壤侵蚀特征研究 总被引：1，自引：0，他引：1
[目的] 探讨广西壮族自治区典型赤红壤集约化蔗区小流域的土壤侵蚀状况,以及土壤侵蚀强度与不同坡度、土地利用类型的关系,为广西集约化蔗区小流域防治土壤侵蚀提供科学参考。[方法] 在GIS空间分析技术支持下,利用修正的通用土壤流失方程（revised universal soil loss equation,RUSLE）对其进行定量估算。[结果] ①那辣小流域坡度在0°~35°之间,坡耕地（甘蔗）、林地（桉树）分别占土地利用总面积的82.85%,10.99%,道路和沟渠共占6.16%。2020年流域平均土壤侵蚀速率为22.97 t/（hm2·a）,属轻度侵蚀水平,是水利部规定的南方红壤丘陵区土壤允许流失量5 t/（hm2·a）的4.6倍;②流域土壤侵蚀主要发生在5°~25°的坡度范围内,是预防和治理水土流失的重点区域;③不同土地利用类型中,平均侵蚀速率最大的是林地（桉树）,为53.59 t/（hm2·a）,分别是坡耕地（甘蔗）、道路、沟渠的2.84,2.12,27.91倍。[结论] 应用RUSLE模型通过借助软件输入相关参数和处理数据,即可估算出蔗区土壤侵蚀及不同坡度、土地利用类型的土壤侵蚀强度分布特征,应合理规划并利用管理好流域的坡耕地（甘蔗）、林地（桉树）、道路等土地利用类型,采取具有针对性的、有效的水土保持措施。 相似文献
9.
东北漫川漫岗区侵蚀沟发育特征研究 总被引：9，自引：0，他引：9
东北漫川漫岗区位于黑土区核心位置,侵蚀沟发育严重。利用3S获取侵蚀沟数量、长度等数据,计算降雨侵蚀力、坡度、坡长,分析侵蚀沟发育特征及三因素对侵蚀沟发育影响。结果表明:东北漫川漫岗区75.11%的发展沟处于发育初、中期,潜在发育危险性较大,沟蚀剧烈程度地域性差异显著,研究区南、北部沟壑密度分别为0.3,0.06km/km2;地形、冻融历时、温差等差异造成降雨侵蚀力对北部侵蚀沟发育影响显著,南部相对较弱;研究区坡度与坡长呈正相关关系,北部坡缓造成坡度与沟壑密度呈线性增加关系,南部坡陡造成坡度与沟壑密度呈线性减小关系,北部、南部地形因子与沟壑密度分别呈线性增加、减小关系,随着坡长的增加,沟壑密度先增加后减小,临界坡长为900m。 相似文献
10.
[目的] 对福建省水土保持功能重要性进行评价，为该省生态保护红线划定提供科学参考。[方法] 基于GIS技术，利用降水、土壤、数字高程和植被指数等数据，采用修正通用水土流失方程（RUSLE），估算福建省土壤保持量，并对其分级。[结果] 全省土壤保持总量为2.65×109 t/a，平均土壤保持模数为20 789.82 t/（km2·a）。水土保持功能极其重要区、高度重要区、中等重要区、较为重要区和一般重要区面积分别为3 192.54，8 205.54，15 547.71，21 519.81，74 000.20 km2，分别占全省面积的2.61%，6.70%，12.70%，17.57%和60.42%。[结论] 福建省水土保持功能极其重要区、高度重要区和中等重要区主要分布在闽西和闽中2大山带及其周边丘陵山地区。 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.
《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
14.
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
15.
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
16.
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
17.
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
18.
《Communications in Soil Science and Plant Analysis》2012,43(7):865-877
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.
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
20.
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