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1.
为探讨牛粪发酵沼液的抑菌机理,以立枯丝核菌为研究对象,进行了试验研究。采用平皿培养方法：培养基表面分别均匀涂布1 mL 5种不同处理的沼液,即不作处理沼液、沼液灭菌、离心上清液、无菌膜滤液和菌体溶液,中心接种立枯丝核菌并于生化培养箱中28℃培养96 h,每12 h测量立枯菌落的生长直径以计算抑制率,同时借助分子生物学手段鉴定了沼液中起抑制作用的微生物。试验结果表明菌体溶液和不作处理沼液对立枯的抑制效果较好,抑制率最高可达74%和53%,离心上清液的抑制效果次之,无菌膜滤液和沼液灭菌处理的抑制作用较弱,一般在20%以下;对沼液中的微生物菌群进行了分离、纯化与筛选,获16株菌种,并与立枯丝核菌进行对峙培养试验,其中nfd-9和nfd-16具有较强抑制作用,其他菌株几乎没有抑制作用。将nfd-9、nfd-16与立枯对峙交界面处进行了扫描电镜观察,结果显示：这2株微生物通过竞争、拮抗和重寄生等作用来抑制立枯丝核菌的生长,从而到达防止病害的目的。经分子生物学技术鉴定,确定了nfd-9和nfd-16分别为米根霉菌（Rhizopus oryzae）和哈茨木霉（Trichoderma harzianum）。研究结果为进一步了解沼液抑制真菌的机理提供一定的理论参考。 相似文献
2.
采用菌丝生长抑制和分生孢子萌发抑制的试验方法,以草莓枯萎病菌为靶标病原菌,研究了江苏省内运行稳定的21个大型沼气工程的沼液及其无菌滤液对草莓枯萎病菌的生长抑制特性。结果表明,所有沼气工程的沼液对草莓枯萎病菌的菌丝生长都有不同程度的抑制作用,不同运行年限的沼气池沼液以及不同发酵原料的沼液对草莓枯萎病菌的抑制效果均无显著差异,但不同贮液阶段的沼液对其抑菌效果影响显著。沼液的无菌滤液对草莓枯萎病菌菌丝的生长没有抑制作用;沼液及其无菌滤液对草莓枯萎病菌分生孢子的萌发均有不同程度的抑制作用,猪粪沼液及其无菌滤液对草莓枯萎病菌分生孢子萌发的抑制作用好于牛粪沼液。沼液对生产上常见的5种植物病原真菌的抑制效果有显著差别。沼液中的拮抗微生物是沼液抑菌防病的主要因子。 相似文献
3.
为探究有机废弃物蚯蚓粪和活性污泥浸提液对马铃薯致病菌立枯丝核菌（Rhizoctonia solani）和尖孢镰刀菌（Fusarium oxysporum）的抑制作用,该研究采用皿内生长速率法测定了蚯蚓粪和活性污泥浸提液及二者混和液的抑菌作用,并通过盆栽试验分析了它们对马铃薯促生抑病效果。结果表明,蚯蚓粪和活性污泥浸提液对立枯丝核菌和尖孢镰刀菌均有显著的抑制作用,浸提液的100倍稀释液对立枯丝核菌抑制作用分别可高达78.3%和98.8%,对尖孢镰刀菌的抑制作用分别为60.1%和75.8%;2种废弃物浸提液混合后具有协同增效作用,混合液稀释1000倍后,对立枯丝核菌的抑制率为98.6%,对尖孢镰刀菌的抑制率为72.6%。将有机废弃物浸提液高温灭菌后,对病原菌抑制效果极大的下降,与空白对照相比相差较小。盆栽试验结果表明,蚯蚓粪和活性污泥的浸提液能有效防治马铃薯茎溃疡病,2种浸提液1∶1混合稀释200倍后,防治效率高达75.0%。而且蚯蚓粪和活性污泥浸提液灌根施用能促进马铃薯幼苗的生长,浸提液1∶1混合稀释200倍后施用,与对照相比株高增长了56.8%。综上,有机废弃物蚯蚓粪和活性污泥浸提液对马铃薯致病菌具有显著抑制效果,2种废弃物浸提液混合施用对马铃薯茎溃疡病的防治有协同增效作用。 相似文献
4.
本试验在实验室条件下,研究大中型沼气工程猪沼和牛沼两种沼液原液及其离心上清液对大豆尖孢镰刀菌、大豆菌核病菌、小麦纹枯病菌、小麦根腐病菌、水稻纹枯病菌、玉米大斑病菌和玉米小斑病菌等7种农作物病原真菌的抑制作用。结果表明：猪沼原液和牛沼原液对其中的大豆尖孢镰刀菌、大豆菌核病菌、小麦纹枯病菌、小麦根腐病菌和水稻纹枯病菌5种病原真菌具有较好的抑制作用,其菌丝生长抑制率均在72%以上,但对玉米大斑病菌和玉米小斑病菌的菌丝生长基本没有抑制作用;相比之下,猪沼和牛沼离心上清液对以上5种病菌的菌丝生长抑制作用明显减弱,除猪沼离心上清液对大豆菌核病菌的菌丝生长抑制率大于70%以外,试验中猪沼和牛沼离心上清液对实验病原菌的菌丝生长抑制率基本都在60%以下。试验结果显示猪沼液和牛沼液对农作物病原真菌具有潜在的植物病害防治作用,为养殖场大中型沼气工程沼液应用新技术的开发提供科学依据。 相似文献
5.
立枯丝核菌毒素的研究进展 总被引：1，自引：0，他引：1
立枯丝核菌(Rhizoctonia solani kühn)寄主范围广且腐生性强,主要危害禾本科、茄科、豆科和十字花科等43科260多种植物,造成水稻、玉米和马铃薯等作物产量严重减少以及品质下降。目前种质库中尚未发现高水平的抗源,因此无法借助转基因手段培育抗立枯丝核菌的新材料。立枯丝核菌致病因子主要为毒素和细胞壁降解酶,基于病原菌和植物互作关系,本文着重阐述了立枯丝核菌毒素提取工艺的发展、成分鉴定、生物活性及致病机理,旨在为进一步深入研究立枯丝核菌及其相关病害的有效防治提供一定的理论依据。 相似文献
6.
生物防治微生物的应用方式对生防效果具有显著影响。本研究利用分离到的生防菌株T12孢子粉、有机肥吸附菌丝(菌丝吸附)和固体发酵产品(固体发酵)3种水稻纹枯病生防菌的应用方式,研究了3种应用方式对水稻纹枯病发病率、微生物数量以及水稻抗病性酶活性的影响,分析了不同应用方式的生防效果。结果表明,生防菌株T12鉴定为棘孢木霉(Trichoderma asperellum)。孢子粉、菌丝吸附和固体发酵的应用方式都能够防控水稻纹枯病,其中固体发酵应用方式的防效最好,防治率为89.5%。相较于孢子粉处理,应用菌丝吸附和固体发酵的方式能够显著(P0.05)增加水田中立枯丝核菌(Rhizoctonia solani)菌核表面附着的木霉菌数量。水稻移栽20 d测定水稻茎秆上木霉菌数量显示,固体发酵和菌丝吸附应用方式有利于木霉菌在水稻茎秆定殖;水稻移栽60 d、100 d和130 d测定木霉菌数量表明,孢子粉处理木霉菌数量高于固体发酵处理,固体发酵处理高于菌丝吸附处理(P0.05)。水稻生育期内,对照处理立枯丝核菌数量从41 cfu-g-1增加到272 cfu-g-1,孢子粉处理和菌丝吸附处理水稻茎秆上立枯丝核菌数量低于对照处理,但均高于固体发酵处理(P0.05)。测定水稻几丁质酶和β-1,3葡聚糖酶活性的结果显示,3种应用方式都能够诱导水稻产生抗性,相较于孢子粉处理,菌丝吸附和固体发酵处理能够在水稻生育期内持续诱导水稻产生抗性。棘孢木霉T12菌株固体发酵产品的应用方式更有利于对水稻纹枯病的生物防控。 相似文献
7.
AM 菌根真菌诱导对提高玉米纹枯病抗性的初步研究 总被引：13，自引：1，他引：13
试验研究玉米接种摩西球囊霉后对纹枯病抗性反应的结果表明,接种摩西球囊霉能明显减轻玉米纹枯病的发病率和病情指数,减轻病害。接种摩西球囊霉还能促进玉米营养生长,但立枯丝核菌侵袭会降低菌根的侵染率,表明摩西球囊霉与立枯丝核菌间存在相互作用。 相似文献
8.
苹果树腐烂病拮抗细菌鉴定及其抑菌作用效果测定 总被引：8，自引：0，他引：8
为了开发一种高效低毒的苹果树腐烂病生防制剂,通过对峙培养法、形态学及分子生物学的方法进行了苹果树腐烂病菌拮抗菌的分离筛选及鉴定,采用离体枝条法测定了拮抗菌对苹果树腐烂病的防效,并采用显微观察和液体培养法分别研究了拮抗菌对苹果树腐烂病菌的抑菌机理和无菌滤液对苹果树腐烂病菌生长的影响。分离筛选结果表明,从甘肃省各苹果产区果园土壤和苹果树枝条上分离得到23株细菌,2株对苹果树腐烂病菌具有较好拮抗作用,分别为LZ-1201和TS-1203,其对苹果树腐烂病菌菌丝生长抑制率分别为79.00%和85.00%。鉴定结果表明,菌株LZ-1201和TS-1203分别为枯草芽孢杆菌(Bacillus subtilis)和解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。离体枝条防效测定表明,拮抗菌无菌滤液对苹果树腐烂病的防效随着稀释倍数增大而降低,原液防效最高,分别为74.43%和77.07%。抑菌作用机理结果表明,两株拮抗菌均可导致苹果树腐烂病菌丝膨大畸形、原生质浓缩、释放及溶解。拮抗菌无菌滤液对腐烂病菌生长的影响测定结果表明,无菌滤液对腐烂病菌分生孢子萌发和菌丝生长量均有显著抑制作用(P0.05),其无菌滤液稀释40倍时对腐烂病菌分生孢子萌发和菌丝生长量的抑制率均高于60%,表明该拮抗菌具有很好的生防潜力。 相似文献
9.
为探究哈茨木霉(Trichoderma harzianum)M-33协同小麦秸秆对马铃薯黑痣病的生防效果,及其对马铃薯根际土壤微生物区系的影响,应用平皿对峙法和扫描电镜技术研究哈茨木霉M-33对立枯丝核菌的拮抗机制,通过盆栽试验研究哈茨木霉M-33协同小麦秸秆对马铃薯黑痣病的防治效果和对马铃薯植株生长的影响,基于稀释平板法和高通量测序技术测定协同处理对马铃薯根际土壤微生物区系的影响。结果表明,哈茨木霉M-33对立枯丝核菌的拮抗机制表现为空间竞争和重寄生;协同处理马铃薯出苗率为100%,对马铃薯黑痣病的防效高达70.26%,明显高于对照;协同处理的马铃薯株高、茎粗和分枝数分别为43 cm、0.82 cm和3.89,均明显高于对照;同时,协同处理后马铃薯根际土壤真菌数量较对照降低了29.54%,而细菌、放线菌和木霉菌数量分别较对照提高了75.36%、60.58%和 1 407.27%; 协同处理对真菌群落多样性、群落结构组成影响较大,对细菌群落多样性、群落结构组成影响较小;协同处理能够促进马铃薯根际土壤中有益微生物的聚集。本研究结果可为生防木霉菌高效利用和马铃薯黑痣病的生物防治提供理论基础。 相似文献
10.
红三叶根际促生菌中具生防效果菌株筛选、鉴定及特性研究 总被引：1，自引：0，他引：1
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.
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.
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
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.
《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