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关中棉花产量波动的某些特征及高产稳产的农业气象指标 总被引：1，自引：0，他引：1
采用正交多项式、方差分析、因子分析等方法，对关中棉区２２年有关资料进行分析，得出关中棉花产量的气候波动指数为０．２５０２，占棉花产量波动的６８．１％；关中棉花产量的４８．６８％取决于气候条件的优劣；气象产量存在着９年主周期和５年次周期；棉花高产稳产的农业气象指标为：５月中旬降水量≤２０ｍｍ、８月下旬～１０月中旬雨日数≤１８ｄ、１０月上旬温差＞８．５℃、８月下旬降水量≤６０ｍｍ、１５℃初、终日期间降水量≤４２０ｍｍ。针对影响棉花产量的不利气候因素，提出了高产稳产措施。 相似文献
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应用鲁西南1980-2009年植保部门棉花资料和气象部门气象资料,利用DPS专业版数据处理系统筛选一批影响棉花生长、产量和品质最优势相关气象因子,分析其相关性及对棉花生长、产量和品质的影响。结果表明:棉花衣分与7月降水量呈显著负相关;8月充足的光照有利于棉花裂铃、吐絮;9月降水量偏多,铃重严重减少。铃重随5月和8月平均气温升高而增加。铃重与5月日照时数呈正相关,光照充足,铃重增加;适宜的降水量对棉花纤维长度有利,降水量过大则棉花纤维长度减小。棉花皮棉及籽棉的产量均与年平均气温呈极显著正相关,说明气温偏高有利于棉花产量形成。分析气候因素对棉花生长及产量的影响,对发展当地棉花产业具有重要意义。 相似文献
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为揭示黄土高原旱地冬小麦田长期产量及水文变化,以山西省万荣县连作冬小麦为研究对象,分析了冬小麦产量1951—2020年变化趋势及气候年际波动对产量的影响,同时利用Hydrus-1D模型和标定的模型参数模拟了1965—2020年田间水量平衡要素各分量的变化过程。结果表明：试验地冬小麦产量多年平均增产率是31.9 kg/(hm2·a),年际气候变化对冬小麦产量的影响达到±22.4%,其中影响最为显著的气象要素是生育期平均相对湿度和全年降水量;标定期和验证期Hydrus-1D模型的决定系数分别为0.65～0.68,0.57～0.65;近56 a冬小麦平均蒸腾量为(176±29) mm,土壤蒸发量为(296±28) mm占降水量的60%～80%,渗漏量一般小于40 mm,土壤含水量变化为(-2±45) mm。综上,研究地70 a冬小麦产量呈上升趋势,且受年际气候变化的影响其产量波动较大。Hydrus-1D模型能够较好地模拟晋南旱塬冬小麦田的水文变化情况,多年来研究地冬小麦田土壤含水量呈下降趋势。 相似文献
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陇东地区几种旱作作物产量对降水与气温变化的响应 总被引：3，自引：1，他引：2
研究作物产量对气候变化的响应,对于指导区域农业生产,保障粮食安全和生态安全具有一定的理论指导意义。结合大田试验与农业生产系统模拟模型(Agricultural Production Systems Simulator,APSIM),在验证模拟研究区冬小麦、玉米和紫花苜蓿产量可靠性的基础上,分析5个降水变化梯度(降水量不变、降低10%和20%、升高10%和20%)和5个气温变化梯度(不变、降低1.5和1℃、升高1.5和1℃)组合情景下3种作物的产量变化趋势。结果表明:APSIM模型在试验点对3种作物籽粒产量和生物量的模拟精度较高,决定系数R2在0.80~0.93之间,归一化均方根误差在11.35%~22.48%之间,模型有效系数在0.53~0.91之间。冬小麦、玉米和紫花苜蓿在气温升高、降水量减少的情景下减产,减产的最大幅度分别为38.7%、40.3%和41.8%;冬小麦、紫花苜蓿的在气温降低、降水量增加时增产,增产的最大幅度分别为29.8%和51.7%;玉米在降水量增加、温度不变的情景下增产幅度最大,为22.0%。总之,在研究范围内,3种作物的产量随降水的增加而增高;玉米的产量随气温升高先增高后降低,另2种作物的产量随气温的升高而降低;紫花苜蓿适应气候变化的能力最强。结果对明确黄土高原地区主要作物的生产走势,制订农业布局、管理措施等具有一定意义。 相似文献
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通过分析近32a(1980-2011)荆州棉花生长季降水量资料,针对棉花4个生育期对水分的需求,进行作物旱涝等级划分。结果表明,荆州棉花生长季内发生的水分胁迫以渍涝为主,无干旱胁迫;苗期降水量普遍多于需求,渍涝风险高;蕾期和吐絮期发生渍涝的频率远高于干旱,且多发生大涝和重涝;花铃期干旱发生频率略高于渍涝。将研究区历年棉花产量分离为趋势产量和气象产量,气象产量与各生育期旱涝程度的相关关系表现为,气象产量与全生育期和花铃期降水距需百分率呈极显著负相关(P0.01),与吐絮期降水距需百分率呈显著负相关(P0.05)。棉花生长季内降水量超出需求越多,气象产量越低;除降水量显著偏少的年份外,降水越少,气象产量越高。通过采用距需百分率法划分棉花各生育期的旱涝等级,充分揭示了各生育期需水量与降水总量间的平衡与矛盾,对江汉平原棉花种植区不同旱涝年景及不同月份的田间水分管理与高效利用具有一定指导意义。 相似文献
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基于AquaCrop模型的气候变化对陕西省冬小麦产量影响模拟分析 总被引：1，自引：0，他引：1
通过分析陕西省3个地区(延安、长武及安康)1957—2013年气温和降水等气象因子的变化,运用AquaCrop模型模拟分析了在现状降雨条件下,气温及CO_2浓度等气象因子变化对陕西省冬小麦产量的影响。结果表明:气温升高0.1℃,长武及安康分别减产0.3%和0.7%,延安增产0.5%;延安和安康CO_2浓度增加20μmol/mol,两地分别增产3.6%和4.2%,长武CO_2浓度增加10μmol/mol,增产2.2%;气温和CO_2浓度同时变化(即气温升高0.1℃同时延安和安康CO_2浓度增加20μmol/mol,长武增加10μmol/mol),延安、长武和安康分别增产4.0%,2.0%,3.6%。在仅考虑气温及CO_2浓度变化的情况下,与2012年相比未来18年3种典型年(枯水年、平水年和丰水年)下,3个地区因区域而表现不同,延安冬小麦增产3.3%～10.3%,长武增产2.3%～10.0%及安康增产1.8%～9.8%。可见,气温与CO_2浓度增加,陕西省"暖干+高碳型"或"暖湿+高碳型"气候有利于冬小麦产量的提高,延安长武安康,即可在陕北地区适度增加冬小麦种植面积,提高农业产量。 相似文献
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新疆喀什气候变化对棉花发育期及产量的影响分析 总被引：3，自引：0，他引：3
利用喀什国家基准气候站1961—2013年53 a的平均气温、平均最高气温、平均最低气温、降水量以及日照时数资料,结合1990—2013年的棉花发育期、单位面积产量、"三桃"数等资料,采用线性倾向估计计算、检验方法、气候趋势系数和气候倾向率方法,对1961年以来喀什气候变化特征、1990年以来棉花发育期和产量进行分析,探讨了喀什近期气候变化对棉花生产的影响。结果表明:近53 a来,喀什年和各季平均气温、平均最高气温、平均最低气温总体呈线性上升趋势,其年气候倾向率为0.25~0.47℃-10a-1(P-0.01),春、夏、秋3个季节的倾向率分别为0.24~0.47℃-10a-1(P-0.05)、0.09~0.37℃-10a-1、0.32~0.46℃-10a-1(P-0.01),其中春、秋季平均最低气温的升温率最大。年降水量呈明显增多趋势,其增幅为6.16 mm-10a-1,对各季节降水而言,春季降水量呈减少趋势,其气候倾向率为-0.44 mm-10a-1,夏、秋季降水量呈明显的增多趋势,其增幅分别为2.10 mm-10a-1、2.23 mm-10a-1(P-0.05)。日照时数呈增多趋势,其气候倾向率分别为31.3 h-10a-1(P-0.05)(年)、16.16 h-10a-1(P-0.01)(春)、9.84 h-10a-1(P-0.05)(夏)、4.27 h-10a-1(P-0.01)(秋),其中春季日照时数的增幅最大。近53 a来,喀什初霜日呈推后趋势(1.4 d-10a-1)、终霜日呈提前趋势(-1.3 d-10a-1),无霜期延长明显(1.0 d-10a-1)。近23 a来喀什棉花生长发育期资料统计指出,棉花播种期、出苗期、三真叶期、五真叶期、现蕾期、开花期、裂铃期、吐絮期等各发育期均表现出不同程度的提前趋势,其中现蕾期的提前趋势最明显,为6.6 d-10a-1(P-0.01);棉花停止生长期呈延迟趋势,即延迟幅度为4.2 d-10a-1(P-0.01),发育期的延长对棉花产量和品质的提高都十分有利。棉花"三桃"数中,伏前桃数、伏桃数和秋桃数呈增多趋势,其增幅分别为0.58个-10a-1、0.92个-10a-1和0.49个-10a-1。近23 a棉花生产中,平均产量呈增多趋势,其增幅为373.5kg-hm-2-10a-1(P-0.01)。影响棉花发育期和产量的主要气候因子有气温、日照时数、降水、初终霜日、无霜期。总之,喀什气候的变化对棉花生产的影响以积极影响为主,气候变暖有利于提高棉花的产量和品质。本文中,初、终霜冻日及无霜期与棉花产量总体呈正相关,初霜日推后、终霜日提前、无霜期延长,棉花产量增多。 相似文献
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陕西省近50年来降水量时空变化特征分析 总被引：3，自引：0，他引：3
研究使用陕西省以及临近陕西省近50 a来的39个站点年降水数据,运用Mann-Kendall非参数检验法、累积距平法和GIS插值,分析了近50 a陕西省的降水变化趋势和降水时空分布及变化特征。结果表明:1）近50 a来陕西省降水量存在明显的波动变化,呈现“增加—减少—增多—减少—增多”的波段形态。从总体趋势看,降水序列是呈现减少趋势,减少的速率是14.59 mm/10 a。2）在近50 a,陕西省降水量在1967年和1985年出现两次突变,出现了两个峰值。3）陕西省降水量分布及变化和降水等值线分布存在明显的纬向区域差异,降水总体出现北少南多的规律;陕北比较稀疏,而陕南以及关中比较密集。4）受到季风和地形的共同影响,陕西省的降水也存在经向差异,陕北降水量呈东多西少,关中和陕南呈现西多东少的分布格局。 相似文献
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为了探讨农林牧地土壤氮肥力水平,我们在陕北杏子河流域的茶坊一带,选择具有代表性的林地和草地以及条件相似的农地,研究了土壤的氮矿化势,为提高土壤氮肥力提供依据。一、基本情况茶坊位于陕西省安塞县西部丘陵沟壑区,海拔高度1,100—1,600米,属暖温带半干旱大陆性气候,年平均气温9.3℃,年降水量500—600毫米。降水量变化大,分布不均,多集中在7、8、9三个月,占年降水量的60—70%。春季干旱,多西北风;夏季气温高,多暴雨。年平均蒸发量1,800—2,200毫米,比降水量大2.6倍。由于长期单一农业和滥垦、滥牧,破坏了植被和土壤,生态系统遭受破坏,水土流失严重,产量不高。采样地点在蟠龙山(1—5号)和庙沟疙瘩(6—8号)的黄土梁峁坡上,具体位 相似文献
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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
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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