不同年代培育的棉花品种产量性状及氮利用效率特征

棉花品种培育过程与土壤培肥、栽培技术、气候变化等因素密切相关,品种产量性状的选育也与养分吸收利用性状存在协同选择性。为了理解品种选育过程对棉花养分效率的影响,采用单因素随机区组设计,比较了新疆1950s—2013年不同年代培育的22个棉花品种（系）的产量性状和氮素利用效率的特征,分析了各棉花品种不同生育期生物量积累规律、产量性状和氮素利用效率的差异。结果表明：不同品种生物量、产量、氮素利用效率和氮素偏生产力差异较大,生物量苗期、蕾期、花铃期和吐絮期分别为2.87~11.67 g·株^-1、20.8~38.6 g·株^-1、42.3~88.3 g·株^-1和58.2~120.4 g·株^-1,变异系数分别为30.2%、8.2%、5.6%和5.6%。产量构成因素中单株铃数变异系数最大（29.0%）,衣分最小（1.0%）。氮素利用效率和氮素偏生产力分别为1.12~4.47 kg·kg^-1和2.87~11.67 kg·kg^-1,变异系数分别为35.3%和27.6%。氮素偏生产力与生物量、皮棉产量呈极显著正相关。新疆过去60年棉花品种更替过程中,经济系数没有发生明显改变,始终维持在0.20~0.24 g·g^-1;棉花皮棉产量性状逐渐提升,由1950s的853.6 kg·hm^-2增加到2013年的1 569.8 kg·hm^-2;氮素偏生产力和氮素利用效率变化较大,分别由4.12 kg·kg^-1增加到7.58 kg·kg^-1、由2.32 kg·kg^-1增加到3.07 kg·kg^-1。基于生物量、产量构成因素、氮肥利用效率和氮素偏生产力等性状指标的综合评价和聚类分析,将22个品种分为氮高效型、氮中效型和氮低效型3组,‘新陆早50号’ ‘新陆早57号’为氮高效型品种。与氮低效型组相比,氮高效型组的品种具有较高的皮棉产量和生物量。通过上述结果可以认为,棉花高产育种过程提高了氮素利用效率和偏生产力。     

红豆和白扁豆种子萌发和生长对盐胁迫的响应及其生理机制

为探讨红豆和白扁豆种子萌发及幼苗生长对盐胁迫的响应及其生理机制,以红豆品种‘渝红豆2号’和传统白扁豆品种为材料,分别用不同浓度NaCl （0 mmol·L^-1、20 mmol·L^-1、40 mmol·L^-1、60 mmol·L^-1、80 mmol·L^-1、100 mmol·L^-1）溶液处理种子,测定不同NaCl浓度胁迫下红豆和白扁豆种子的发芽指标及幼苗生长指标、叶片丙二醛（MDA）含量、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性,分析NaCl胁迫对红豆和白扁豆种子萌发及幼苗生长的影响。结果表明：1）随NaCl浓度增加,红豆和白扁豆种子发芽率、发芽势、发芽指数和活力指数均呈下降趋势。当NaCl浓度为80 mmol·L^-1时,白扁豆发芽势、发芽指数、活力指数降为0,红豆的发芽势、发芽指数、活力指数分别为20.00%、2.00、0.83;NaCl浓度为100 mmol·L^-1时,红豆的发芽率为16.67%,但白扁豆为0,这表明在盐胁迫下红豆较白扁豆具有更高的萌发能力。2）红豆与白扁豆相对盐害率随NaCl浓度的增加而增加,当NaCl浓度为80 mmol·L^-1和100 mmol·L^-1时,白扁豆相对盐害率为96.58%和96.67%,红豆相对盐害率为47.05%和83.18%,说明红豆受盐害程度较低。3）红豆与白扁豆幼苗胚根、胚芽及鲜重均随NaCl浓度增加而下降。NaCl浓度为100 mmol·L^-1时,白扁豆胚根长为0,红豆胚根长为0.23 cm。4）随NaCl浓度升高,红豆和白扁豆叶片的MDA含量均增加,造成细胞膜透性逐渐增大,但是红豆幼苗MDA积累量低于白扁豆,这表明红豆叶片细胞膜损伤较小。5） NaCl胁迫下,红豆与白扁豆SOD活性均显著升高,但红豆SOD活性显著高于白扁豆;NaCl胁迫下,POD活性显著升高,但白扁豆POD活性显著下降。研究发现红豆可通过提高SOD和POD活性以降低细胞膜氧化伤害,减少MDA积累量,进而提高种子萌发能力。在相同浓度NaCl胁迫下红豆较白扁豆有更高的耐盐性,能更好地适应盐胁迫环境。     

洪泽湖地区麦稻两熟农田及杨树林地降雨径流对地下水水质的影响

农业氮磷养分流失已经成为地下水污染的重要原因之一,为了探究和比较麦稻两熟农田和杨树林地氮磷流失对地下水的影响,本文在洪泽湖河湖交汇区设置农田和杨树林监测小区和监测井,进行了为期1年的地表养分流失和地下水水质监测。结果表明：1）林地雨前雨后表层土壤含水量均小于麦田,麦田土壤含水量较雨前平均提高8.95%,林地提高4.05%。2）麦田和杨树林地表层土壤硝态氮、铵态氮及有效磷流失总量分别为63.53 mg·kg^-1、5.61 mg·kg^-1及57.43 mg·kg^-1和16.78 mg·kg^-1、2.45 mg·kg^-1及0.73 mg·kg^-1,稻季田面水硝态氮、铵态氮、可溶性磷和颗粒态磷流失总量为8.32 mg·L^-1、27.44 mg·L^-1、2.39 mg·L^-1和2.99 mg·L^-1,监测期内杨树林氮磷流失总量明显低于农田。3）农田表层养分流失量与降雨量存在密切关系,基本随降雨量增大呈对数增长,而杨树林几乎不受降雨影响。4）农田产生径流的理论最小降雨量（麦田：3.3 mm;稻田：4.2 mm）远小于杨树林地（22.8 mm）,麦田铵态氮、正磷酸盐浓度,稻田和杨树林地总氮、硝态氮、铵态氮、总磷、可溶性磷、正磷酸盐浓度与降雨量存在显著相关性。5）农田径流中养分浓度与地下水氮磷含量存在显著相关性（P<0.05）,而杨树林地地下水氮磷含量保持在相对稳定水平,与径流中养分浓度无明显相关性。与农田相比,林地能够更好地控制径流养分流失,缓解地下水污染,有利于农业面源污染的控制。     

九龙坡花椒种植区地形、土壤肥力与花椒产量的关系

为了解九龙坡花椒种植区土壤养分状况及该区地形因子、土壤肥力因子与花椒产量的关系,为科学合理制定花椒高效施肥措施提供理论依据,本研究采用田间调查研究和室内分析的方法,研究了九龙坡花椒种植区低、中、高产区的海拔、坡度及土壤pH、有机质、大量微量元素含量和交换性能的变化特征,及其与花椒产量的关系。研究结果表明：九龙坡花椒普遍种植于200~500 m海拔范围,高产区集中在300 m左右的海拔;从低产区到高产区坡度略有增加,但未达显著水平。土壤均属酸性土,pH<6.5。土壤肥力总体属高水平范围,但各养分因子差异很大,其中土壤阳离子交换量（CEC）、有效磷、有效钙、有效镁、有效铁、有效锰、有效铜、有效锌含量丰富,分别为27.2 cmol（+）·kg^-1、35.2 mg·kg^-1、3 289.8 mg·kg^-1、271.8 mg·kg^-1、48.6 mg·kg^-1、62.1 mg·kg^-1、1.5 mg·kg^-1、4.5 mg·kg^-1;有机质、碱解氮、速效钾、交换性酸属适中水平,分别为19.1 mg·kg^-1、114.9 mg·kg^-1、107.0 mg·kg^-1、8.1 cmol（+）·kg^-1;水溶性硼缺乏,为0.28 mg·kg^-1。相关分析表明花椒产量与有效钙、CEC、pH、有效锰、水溶性硼呈显著正相关;通径分析结果表明有效钙、CEC、交换性酸、有效铜、有效铁、有效锌是影响花椒产量的主要因子,逐步回归分析构建了有效钙（X₆）与花椒产量（Y）的最优回归线性方程：Y=11.693+0.003X₆。综上所述,九龙坡花椒种植区土壤养分失衡较为严重,施肥应注重养分的平衡,增施有机肥,改善土壤理化性状,治理土壤酸化。     

CO2浓度升高条件下不同程度豌豆蚜危害对紫花苜蓿叶片营养物质和次生代谢物质的影响

由于人类大量开采使用石油、煤炭、天然气等化石燃料,使大气CO₂浓度升高,这不但加速全球变暖,还将影响地球上动植物的生存和分布,从而对整个生态系统产生深远影响。为探明CO₂浓度升高与豌豆蚜（Acyrthosiphon pisum）虫口密度对紫花苜蓿（Medicago sativa）叶片内化学物质的影响,明确CO₂浓度升高和蚜虫密度在紫花苜蓿生理生化中的作用,试验在CO₂光照培养箱内设置380 μL·L^-1（对照）、550 μL·L^-1和750 μL·L^-1 3个CO₂浓度培育苜蓿幼苗并接入10日龄成蚜10头·株^-1、20头·株^-1、30头·株^-1,并以0头·株^-1作为空白对照,1周后测定植物体内营养物质和次生代谢物质含量。结果表明,随CO₂浓度升高,蚜虫密度为30头·株^-1时紫花苜蓿可溶性蛋白、可溶性糖以及淀粉含量均上升,在750 μL·L^-1 CO₂浓度下分别比CK上升11.62倍、0.49倍和0.24倍;黄酮、总酚和简单酚含量也显著上升。随蚜虫危害程度加重,同一CO₂浓度下紫花苜蓿淀粉、简单酚含量先上升后下降,高CO₂浓度蚜虫密度为30头·株^-1时比0头·株^-1时可溶性糖、总酚以及单宁含量上升1.66倍、1.49 mg·g^-1和1.09 mg·g^-1,差异均显著（P<0.05）。说明具有固氮作用的豆科植物更易于适应CO₂浓度升高的变化,从而在受到刺吸胁迫后增强自身诱导抗虫性以抵御害虫为害。     

La(NO3)3 对盐胁迫下黑麦草幼苗生长及抗逆生理特性的影响

为探讨稀土元素镧(La)对牧草盐胁迫伤害的缓解作用, 采用水培法研究了叶面喷施20 mg·L^-1La(NO₃)₃ 对NaCl 胁迫下黑麦草幼苗生长及其抗逆生理特性的影响。结果表明: 盐胁迫显著抑制黑麦草幼苗的生长, 提高叶片电解质渗漏率及丙二醛(MDA)、O₂^- 和H₂O₂ 含量, 其作用随盐浓度的增大而增强。超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)活性和抗坏血酸(AsA)、谷胱甘肽(GSH)、可溶性蛋白质、脯氨酸含量随盐浓度增大呈先升后降趋势, 可溶性糖和Na⁺/K⁺比逐渐增大, 质膜H⁺-ATP 酶活性逐渐降低, 过氧化物酶(POD)活性及POD 同功酶数量表达增强。喷施La(NO₃)₃ 处理可降低盐胁迫下黑麦草幼苗叶片的O₂^- 和H₂O₂ 含量, 提高SOD、CAT、POD、APX 和质膜H⁺-ATP 酶的活性及POD 同功酶的表达, 使AsA、GSH、可溶性蛋白质、可溶性糖和游离脯氨酸含量及幼苗生物量增加, Na⁺/K⁺比降低。表明La(NO₃)₃ 可通过提高抗氧化系统的活性和积累渗透溶质减轻盐胁迫伤害, 从而提高黑麦草的耐盐性。     

铅胁迫下接种AM真菌对龙葵根际土壤微生物群落代谢特征的影响

为从微生态角度探索接种AM真菌对铅污染根际土壤微生物群落代谢特征的影响,以摩西管柄囊霉（Funneliformis mosseae）和幼套近明囊霉（Claroideoglomus etunicatum）为接种菌剂,在温室盆栽条件下以Pb⁴⁺含量为0 mg·kg^-1、200 mg·kg^-1、400 mg·kg^-1和800 mg·kg^-1土壤种植龙葵（Solanum nigrum）10周后采集根际土壤,采用Biolog微平板法测定龙葵根际土壤微生物群落的代谢变化。结果表明：1）微生物平均代谢活性（AWCD）随铅浓度增加呈降—升—降趋势;接种AM真菌显著提高了铅胁迫下根际土壤微生物的AWCD值,仅中浓度（400 mg·kg^-1）下未达显著差异。2）中浓度铅处理能显著提高根际土壤微生物对糖类及其衍生物、氨基酸类、脂肪酸和脂类及代谢产物类四大类碳源底物利用能力;接种AM真菌,高浓度（800 mg·kg^-1）铅处理显著提高了根际土壤微生物对氨基酸类底物的利用能力。3）铅胁迫下接种AM真菌提高了根际土壤微生物多样性指数,在中浓度下丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数均达显著水平。4）主成分分析显示,代谢产物类在PC1和PC2中种类最多,分别为6种和4种;糖类及其衍生物在PC3中种类最多（5种）。5）在铅胁迫和接种AM真菌共同作用下,微生物碳源利用主要受铅浓度调节,并且二者对微生物碳源利用具有显著交互效应。综上可知,接种AM真菌能够提高铅胁迫下龙葵根际土壤微生物多样性指数,增强根际土壤微生物对碳源底物的利用能力。该研究为进一步探究AM真菌强化植物联合修复技术提供了依据。     

盐胁迫对番茄种子萌发中多胺形态变化和抗氧化的影响

以番茄“合作903”为材料,研究25~200 mmol·L^-1 NaCl胁迫对其种子发芽、种子活力指数（SVI）、丙二醛（MDA）含量、保护酶活性、溶质积累和不同形态多胺含量的影响。结果表明：25、50 mmol·L^-1 NaCl处理7 d,不影响番茄种子发芽率,但显著降低SVI;随着盐处理浓度上升,发芽率和SVI均显著下降。分别以种子发芽率和SVI为因变量,NaCl处理浓度为自变量,种子萌发和萌发后幼苗建成的耐盐阈值分别为106.1 mmol·L^-1 NaCl（0.62%）和43.38 mmol·L^-1 NaCl（0.25%）。随着NaCl处理浓度上升,萌发种子MDA含量显著上升,保护酶活性、可溶性蛋白（SP）和可溶性糖（SS）均上升,游离态腐胺（fPut）、游离态亚精胺（fSpd）和游离态精胺（fSpm）、(fSpd+fSpm)/fPut均显著上升,束缚态腐胺（bPut）、束缚态亚精胺（bSpd）、束缚态精胺（bSpm）均显著增加,而(bSpd+bSpm)/bPut变化不明显。与对照相比,50 mmol·L^-1 NaCl处理下,番茄萌发种子结合态亚精胺（cSpd）、结合态精胺（cSpm）含量及(cSpd+cSpm)/cPut均极显著上升,随着NaCl处理浓度上升,cPut、cSpd、cSpm含量及(cSpd+cSpm)/cPut均逐渐下降。综上所述,盐胁迫延缓、抑制番茄种子萌发,对于萌发后幼苗的建成抑制作用更强。番茄种子萌发阶段对盐分具有一定的抗性,主要由于番茄萌发种子中多胺代谢在盐胁迫下呈现(fSpd+fSpm)/fPut比值的急剧上升、cSpd和cSpm含量的显著上升和束缚态各多胺的显著积累,同时SS和SP的积累随盐胁迫加剧显著积累,从而提高了萌发种子的抗氧化和渗透调节能力;但是在高盐（150 mmol·L^-1 NaCl）下,cSpd和cSpm的上升调控作用明显减弱,而束缚态各多胺、fSpd和fSpm的上升以及SS和SP积累调控作用仍在增强。     

湘西典型植烟土壤酸碱缓冲特性及影响因素

为探明山地植烟土壤酸碱缓冲特性,采集了湘西山区烤烟典型生产区的28个土壤样本,采用酸碱滴定法和灰色关联法分析了湘西山地植烟土壤酸碱缓冲特性以及土壤缓冲容量与各影响因素之间的量化关系。结果表明：湘西山地植烟土壤酸碱缓冲量为11.35~43.29 mmol·kg^-1,平均为17.26 mmol·kg^-1,黄棕壤的酸碱缓冲量（11.35~43.29 mmol·kg^-1）显著高于黄壤（11.79~20.70 mmol·kg^-1）。有78.57%的样本对酸碱敏感,黄壤土是否对酸敏感由有机质含量决定,黄棕壤土是否对酸敏感与pH和有机质含量密切相关。对于同一土壤类型,有机质和黏粒含量与酸碱缓冲容量显著正相关;对于黄棕壤,酸碱缓冲容量还与pH和阳离子交换量呈显著正相关,与交换性酸和交换性铝呈显著负相关。主要土壤类型之间缓冲性能存在较大差异,黄壤土酸碱缓冲性能主要受土壤有机质、阳离子交换量和黏粒含量的影响;黄棕壤土酸碱缓冲性能主要受pH、阳离子交换量和有机质的影响。在生产中应采用合理施用化肥、增施有机肥、调节土壤酸性等措施提高植烟土壤酸碱缓冲性能,为优质烟叶生产创造良好的生态环境。     

不同磷源对设施菜田土壤速效磷及其淋溶阈值的影响

土壤中磷的移动性不仅取决于磷的数量且与磷肥形态有关。了解不同磷源（有机肥和化肥）对设施菜田土壤磷素的影响对于指导科学施肥和面源污染防治至关重要。本文选取河北省饶阳县3种不同磷含量的农田土壤（未种植过蔬菜的土壤、种植蔬菜30年的塑料大棚土壤和种植蔬菜4年的日光温室土壤）为研究对象,采用室内培养试验和数学模型模拟方法研究有机无机磷源对设施菜田土壤磷素的影响,确定无机肥和有机肥源土壤磷素淋溶的环境阈值。结果表明添加有机肥和无机磷肥都会显著增加3种不同种植年限设施菜田土壤速效磷（Olsen-P）和氯化钙磷（CaCl₂-P）含量,但增加速度不同。对于未种植过蔬菜的低磷对照土壤,磷投入量高于50 mg·kg^-1（干土）后,无机肥比有机肥显著提高了土壤Olsen-P含量。对于已种植蔬菜30年的塑料大棚土壤,高磷投入时[300 mg·kg^-1（干土）和600 mg·kg^-1（干土）],无机肥比有机肥显著提高了土壤Olsen-P含量,低于此磷投入量时有机肥和无机肥处理之间没有显著差异。3种不同农田土壤CaCl₂-P的含量所有处理均表现出无机肥显著高于有机肥处理,尤其是在高磷量[>300 mg·kg^-1（干土）]投入时表现更加明显。两段式线性模拟结果表明,设施菜田土壤有机肥源磷素和无机肥源磷素淋溶阈值分别为87.8 mg·kg^-1和198.7 mg·kg^-1。随着土壤Olsen-P的增加,添加无机肥源磷对设施菜田土壤CaCl₂-P含量的增加速率是有机肥源磷的两倍。因此,建议在河北省高磷设施菜田应减少无机磷肥的投入,特别是土壤速效磷高于198.7 mg·kg^-1的设施菜田应禁止使用化学磷肥和有机肥,在土壤速效磷低于198.7 mg·kg^-1的设施菜田应加大有机肥适度替代无机肥技术的推广。     

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.     

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.     

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.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

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.