清水河上游流域可收集雨水资源量估算与检验

以北京市西部山区典型流域——清水河上游流域为例,采用地理信息系统(GIS)和SCS(Soil Conservation Service)相结合的方法,估算了该流域不同土地利用类型在不同水文年6-8月可收集雨水资源量;并选取2008-2009年6-8月10场降雨的实测径流量数据,与SCS-CN模型计算的径流量进行误差分析,用来检验SCS-CN模型的精确度。结果表明:(1)研究区枯水年(p=75%),平水年(p=50%),丰水年(p=25%)6-8月可收集雨水资源量分别为7.16×10⁷,1.04×10⁸,5.71×10⁷ m³,占全年的平均百分比为82.43%;(2)不同土地利用类型在平水年6-8月可收集雨水资源量占总量百分比分别为:草地和林地占86.13%,耕地和园地占4.87%,工矿仓储用地、住宅等其他土地利用类型占9%;(3)利用SCS-CN模型计算径流值与实测值相比,合格率达到90%。     

宁夏罗山地区2004-2015年NPP时空变化及气候响应

[目的] 揭示罗山保护区植被净初级生产力（NPP）变化规律及气候相关性,为宁夏回族自治区及其周边生态环境保护提供科学依据。[方法] 利用MOD17A3H NPP（2004—2015年）数据、SRTM DEM和罗山周边气象站点（2004—2015年）年均气温和降水数据,运用相关性分析、趋势分析、线性回归分析等方法,分析气候、人口、生态及移民政策等对研究区植被净初级生产力的影响,对区内NPP时空变化特征进行定量化分析。[结果] ①研究区内植被净初级生产力的变化与降水的相关性较高;在核心区,降水与NPP的相关系数R=0.609,置信度p=0.036;在非核心区,相关系数R=0.648,置信度p=0.023;②研究区NPP呈波动增长趋势,速率为0.076 Pg/a（以C计）,高于全国NPP增长速率（0.008 Pg/a）; ③2010—2015年大罗山森林覆盖面积有所增长,NPP介于350～500 g/（m²·a）的森林面积是2004—2009年的4倍,小罗山方向基带植被由荒漠向荒漠草原转化; ④研究区以NPP划分的生态格局主要以荒漠为主（64.9%）,荒漠草原次之（29.6%）,森林占比极低（0.38%）。[结论] 干旱区植被NPP高度依赖降水,罗山地区生态结构有所改善,但森林生态系统仍极端脆弱。     

中国乌鲁木齐土壤中有机氯的来源、组成与风险评价

Twenty-eight surface soil samples from 5 functional zones (park, traffic roadside, business/residential area, rural area, and industrial area) of Ürümqi, China were collected and analyzed for the concentrations of 14 organochlorine pesticides (OCPs), such as 3 isomers of hexachlorocyclohexane (HCHs) (α-HCH, β-HCH, and γ-HCH), 4 dichlorodiphenyltrichloroethanes (DDTs) (p, p’-DDT and its metabolites p, p’-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane) and p, p’-DDE (1,1-dichloro-2,2-bis(4-chorophenyl)ethylene), and o, p’-DDT), and methoxychlor, aiming to survey the residue levels and compositions of these 14 OCPs, to identify possible sources of the OCPs, and to assess their potential risks to human health and the environment in surface soils of Ürümqi. The concentrations ranged from non-detected to 30.86 μg kg^-1 for HCHs (sum of α-, β-, and γ-HCH), from non-detected to 40.03 μg kg^-1 for DDTs (sum of p, p’-DDT, p, p’-DDD, p, p’-DDE, and o, p’-DDT), and from non-detected to 11.95 μg kg^-1 for methoxychlor. The total concentrations of the OCPs ranged from 16.40 to 84.86 μg kg^-1, with a mean of 41.89 ± 16.25 μg kg^-1. According to the measured concentrations and occurrence rates of the 14 OCPs, DDTs, HCHs, and methoxychlor were the most dominant compounds. Among the 5 functional zones, the total concentration of OCPs was in the order of rural area > traffic roadside > park > business/residential area > industrial area. The different compositions of DDTs and HCHs indicated that the residues of these compounds in most soil samples originated from historical application, besides slight recent introduction at some sampling sites. The results of Pearson correlation analysis showed that soil total organic carbon played an important role in the residue levels of HCHs, but such relationships were not found with DDTs or other OCPs. The soil quality of Ürümqi was classified as Class I based on the guidelines of the Chinese Environmental Quality Standard for Soil (GB15618-1995), indicating that the residue levels of OCPs have little risks to the environment and human health in the study area.     

黄土高原典型退耕草地植被特征对土壤入渗过程的影响

植被恢复过程可显著影响土壤入渗性能。通过选取黄土高原典型草地白羊草和铁杆蒿草地,设置不同种植密度（5,10,15,20,25,30株/m²）和采用人工模拟降雨试验（60 mm/h,60 min）,系统研究了草地植被特征对土壤入渗过程的影响。结果表明：（1）种植密度增加可显著延缓产流,不同种植密度下白羊草草地和铁杆蒿草地初始产流时间分别为0.76~5.74,0.87~2.08 s,且随盖度、根系生物量和有机质的增加呈幂函数增加（R²≥0.18,p<0.05）。（2）不同种植密度下白羊草草地的平均入渗速率、稳定入渗速率、入渗总量分别为0.47~0.82,0.46~0.82 mm/min和7.12~11.84 mm,铁杆蒿草地分别为0.38~0.67,0.35~0.60 mm/min和5.70~10.07 mm。当种植密度为20株/m²时,土壤入渗各参数均最大;平均入渗速率、稳定入渗速率、入渗量总量、入渗系数（K）随土壤有机质的提高呈幂函数增大（R²≥0.26,p<0.01）,衰减系数（α）随生物结皮盖度呈降低趋势（p>0.05）。（3）白羊草草地具有较高的根系生物量、生物结皮盖度和有机质含量,其初始产流时间、平均入渗速率、稳定入渗速率、入渗量总量及入渗系数（K）均不同程度高于铁杆蒿草地,衰减系数（α）低于铁杆蒿草地,土壤入渗性能较强。总体而言,对于典型退耕草地,土壤入渗总量（A）可表征为根系生物量密度（RMD）和土壤有机质（SOC）的拟合函数（A=2.77×RMD^0.149 SOC^0.614,R²=0.663,NSE=0.653）。研究结果可为黄土高原退耕草地生态水文过程和植被建设提供数据来源和理论依据。     

生物质炭对土壤N2O消耗的影响及其微生物影响机理

生物质炭在温室气体减排方面具有很大的发展前景,它不仅能实现固碳,对于在大气中停留时间长且增温潜势大的N₂O也能发挥积极作用。本研究采用室内厌氧培养试验,按照生物质炭与土壤质量比（0、1%和5%）加入一定量生物质炭,土壤重量含水率控制在20%。利用Robotized Incubation平台实时检测N₂O和N₂浓度变化,通过测定土壤中反硝化功能基因丰度（nirK、nirS、nosZ）分析生物质炭对N₂O消耗的影响及其微生物方面的影响机理。结果表明：经过20 h厌氧培养后,0生物质炭处理的反硝化功能基因丰度（基因拷贝数·g^-1）分别为6.80×10⁷（nirK）、5.59×10⁸（nirS）和1.22×10⁸（nosZ）。与0生物质炭处理相比,1%生物质炭处理的nirS基因丰度由最初的2.65×10⁸基因拷贝数·g^-1升至7.43×10⁸基因拷贝数·g^-1,nosZ基因丰度则提高了一个数量级,由4.82×10⁷基因拷贝数·g^-1升至1.50×10⁸基因拷贝数·g^-1,然而nirK基因丰度并无明显变化;5%生物质炭处理的反硝化功能基因丰度并未发生显著变化。试验结束时,添加生物质炭处理的N₂/（N₂O+N₂）比值也明显高于0生物质炭处理。相关性分析结果表明,nirS基因丰度和nosZ基因丰度均与N₂O浓度在0.01水平上显著相关。试验末期nirS基因丰度和nosZ基因丰度均随着N₂O浓度的降低而升高。因此在本试验中,添加1%生物质炭可显著提高nirS和nosZ基因型反硝化细菌的丰度,增大N₂/（N₂O+N₂）比值,促进N₂O彻底还原成N₂。生物质炭对于N₂O主要影响机理是增大了可以还原氧化亚氮的细菌活性,促进完全反硝化。     

安徽省沿江地区双季稻光热资源利用效率变化特征及对气象产量的影响

为进一步了解安徽省沿江地区双季稻光温资源利用效率的变化特征及光温资源变化对双季稻气象产量的影响,以安徽省沿江地区19个市县气象观测站1961—2017年逐日日平均气温、日照时数及7个双季稻主产市县1961—2006年早稻和晚稻产量为基础,采用线性趋势、M-K突变检验、相关分析、回归分析等方法,分析了早稻、晚稻、双季稻生长季光热资源和利用效率变化特征及光热资源变化对气象产量的影响。结果表明,1961—2017年安徽省沿江地区早稻、晚稻和双季稻生长季太阳总辐射呈极显著下降趋势（P<0.01）,平均每10 a降幅分别为30.5 MJ·m^-2、69.8 MJ·m^-2和86.6 MJ·m^-2;≥10℃积温呈显著增加趋势,平均每10 a增幅分别为39.1℃·d、24.4℃·d和14.7℃·d。早稻、晚稻、双季稻光能和热量利用效率均呈显著增加趋势（P<0.01）,其中光能利用效率增幅分别为0.040%·（10a）^-1、0.103%·（10a）^-1和0.083%·（10a）^-1,热量利用效率平均每10 a增幅分别为0.141 kg·℃^-1·d^-1·hm^-2、0.39 kg·℃^-1·d^-1·hm^-2和0.315 kg·℃^-1·d^-1·hm^-2;早稻、晚稻和双季稻光热资源利用效率显著增加主要源于其产量的大幅提升。太阳总辐射、≥10℃积温与早稻气象产量分别呈极显著（P<0.01）、显著（P<0.05）正相关;晚稻气象产量与太阳总辐射呈显著（P<0.05）正相关,但与≥10℃积温相关性不显著（P>0.05）。太阳总辐射是影响早稻和晚稻气象产量的主要因子,≥10℃积温为次要因子;光热资源变化对早稻气象产量的影响较晚稻更为明显。在太阳总辐射减少、≥10℃积温增加趋势下,可通过选择光合效率高的品种,并采用薄膜育秧或温室育秧方式,增加早稻生长季积温,适当延长晚稻生育期等途径,提高安徽省沿江地区双季稻光热资源利用效率,实现水稻周年产量的高产稳产。     

北京山区典型植被类型土壤饱和导水率及其影响因素

研究典型植被类型的土壤饱和导水率(K_s)分布及其影响因素,可为北京山区植被建设提供有力借鉴,同时加深对于土壤水分运动的理解。选取北京山区最具代表性的4种植被类型,获取不同类型、不同层次的土壤饱和导水率,调查土壤理化性质与根系生物量、石砾体积,利用Pearson相关性分析、多元逐步回归、通径分析,明晰了北京山区典型植被类型下的土壤饱和导水率分布及其影响因素。结果表明:(1)土壤饱和导水率介于0.05~2.23 mm/min,属于高度变异,随土层向下不断减小,侧柏×灌木混交林、侧柏纯林与侧柏×五角枫混交林的土壤饱和导水率存在显著差异(p＜0.05)。土壤饱和导水率与土层深度之间的关系符合对数函数关系式y=±aln x+b,R²≥0.858。(2)相关性分析结果表明,土壤饱和导水率与容重、总孔隙度、毛管孔隙度、根系生物量、有机质含量均呈极显著相关关系(p＜0.01),与非毛管孔隙度、自然含水率呈显著相关关系(p＜0.05)。(3)逐步回归分析得Y=3.42X₂+0.78X₆-1.333,R²=0.862。进一步通径分析可知,根系生物量主要通过直接作用影响土壤饱和导水率,而总孔隙度通过间接作用影响土壤饱和导水率。可知,侧柏×灌木混交林的导水性能最佳,后续的植被建设应重点考虑侧柏×灌木混交林,以达到减少径流、涵养水源的目的。     

半干旱地区矿区生态系统土壤保持功能评价——以神府—东胜矿区为例

[目的] 评价2000—2020年神府—东胜矿区生态系统土壤保持功能变化情况,探讨矿区生态系统功能现状和存在问题,总结半干旱地区生产建设项目集中区生态功能提升途径,为半干旱地区生产建设项目区生态和经济协调发展提供借鉴。[方法] 采用中国土壤流失方程(CSLE)和风力侵蚀模型,基于栅格像元计算不同时期(2000,2010和2020年)神府—东胜矿区土壤保持量,评价不同土地利用类型、不同植被覆盖度、不同矿井土壤保持量的时空变化。[结果] ①神府—东胜矿区潜在土壤侵蚀量为3.76×10⁶ t/a,矿区生态系统土壤保持量由2000年的2.30×10⁶ t增长到2010年的3.17×10⁶ t,矿区生态系统减少风蚀量作用显著增加。②2000—2020年,矿区耕地、沙地和裸土地面积持续减少,园林草地面积持续增加。园林草地土壤保持量由1.18×10⁶ t/a增加到2.78×10⁶ t/a。③矿区植被由低覆盖度向中高覆盖度转变。2020年,中覆盖度和中高覆盖度林地土壤保持量占矿区生态系统土壤保持总量的67.12%。④治理程度不同的矿井土壤保持量均明显提高。[结论] 2000—2020年,神府—东胜矿区土壤保持功能显著提升。半干旱地区生产建设项目可以通过实施有效的生态措施,改善生产、生活环境,探索生态经济实现路径,实现经济发展和生态改善双赢。     

黄土丘陵区撂荒草地不同生态位物种非结构性碳水化合物对氮添加的响应

为研究氮添加对不同生态位物种非结构性碳水化合物的影响。通过对黄土丘陵区典型撂荒草地进行3年的氮添加试验N0(0 g/(N·m²·a))、N3(3 g/(N·m²·a))、N6(6 g/(N·m²·a))和N9(9 g/(N·m²·a)),[JP]分析了不同生态位物种可溶性糖、淀粉和非结构性碳含量。结果表明:氮添加主要影响占据较高生态位的白羊草(Bothriochloa ischaemum)和长芒草(Stipa bungeana)的非结构性碳水化合物的储存,而对铁杆蒿(Artemisia sacrorum)和杂草影响较小。N6和N9处理对白羊草和长芒草非结构性碳、可溶性糖和淀粉的储存表现出明显的促进作用,这种作用在地上部分表现尤为明显。同时,植物相对重要值与植物地下非结构性碳和淀粉含量显著正相关,而与地上可溶性糖含量和可溶性糖/淀粉显著负相关。研究结果有利于加强对氮沉降背景下不同生态位物种碳储存及分配特征的认识。     

菊芋根系分泌物改良滨海盐土的微生物机制

[目的] 探究菊芋在滨海盐土改良过程中的作用机制,分析菊芋和碱蓬根系分泌物的组分差异,明确土壤微生态环境的变化规律,进一步为盐土改良提供理论依据。[方法] 以种植菊芋和自然碱蓬植被为样地,对菊芋和碱蓬的根系分泌物进行对比分析,研究在根系分泌物作用下土壤微生物数量,微生物量碳氮,微生物群落结构以及土壤酶活性的变化,从而系统地阐明根系分泌物介导下盐土改良的微生物机制。[结果] 菊芋根际土壤中含有果糖（2.343×10^-3 g/kg）、葡萄糖（4.235×10^-3 g/kg）、蔗糖（2.670×10^-3 g/kg）,分别是碱蓬根际土壤的9.28,1.52和2.43倍。而菊芋根际与非根际中的果糖含量存在显著性差异（p<0.05）,其根际中含量为非根际的12.02倍。菊芋土壤还含有低聚果糖（蔗果三糖、蔗果四糖和蔗果五糖）,而碱蓬土壤中未检测出低聚果糖。除糖类外,菊芋根系分泌物还含有烷烃、酚、醛、酯、有机酸、醇、酮、酰胺,其组分较碱蓬土壤更为复杂且某些组分为菊芋特有〔1-氯—十八烷、正十六烷酸、2-甲基-Z-4-十四碳烯、十二酮、（Z）-9-十八碳酰胺、苯丙酸十六烷基酯等〕。功能性根系分泌物（如低聚果糖、果糖、十六烷、十八烷酸等）为根际微生物提供碳源、氮源和营养元素的同时,使菊芋根际土壤中微生物数量显著增加（p<0.05）,土壤微生物量碳、氮显著高于碱蓬土壤（p<0.05）,其值分别是碱蓬土壤的1.95和1.6倍,且菊芋根际的微生物量碳、氮约为非根际的1.69和1.50倍,优势菌群（变形菌门、放线菌门、绿弯菌门、酸杆菌门）所占比重达到90%,土壤有益菌群（Actinobacteria和Acidobacteria）的相对丰度显著增加（p<0.05）,土壤生物活性提升。此外,菊芋根际特有的分泌物（十六烷、烯醛等）,抑制了病原菌的生长,优化了微生物群落结构。除过氧化氢酶外,土壤脲酶、蔗糖酶和碱性磷酸活性显著提高（p<0.05）,其活性分别是碱蓬土壤的1.83,1.88和3.30倍。[结论] 种植菊芋后,通过根际分泌物介导,改善土壤微生物群落结构与功能,增加土壤酶活性,使土壤生物活力得以整体提升,与原生植被碱蓬相比,降低了土壤含盐量,起到了改良盐土的作用。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

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.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“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.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

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.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

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     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

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.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.