黄河口生态恢复工程对湿地土壤不同形态无机硫动态变化的影响

选择黄河口生态恢复前后的未恢复区（R₀）、2007年恢复区（R₂₀₀₇）和2002年恢复区（R₂₀₀₂）的芦苇湿地为研究对象，探讨了生态恢复工程对生长季湿地土壤无机硫形态变化的影响。结果表明，生态恢复工程不同程度地改变了湿地土壤中各形态无机硫含量。相对于R₀，R₂₀₀₂和R₂₀₀₇土壤中的水溶性硫（H₂O—S）含量分别降低46.7%和44.7%，吸附性硫（Adsorbed—S）和盐酸可溶性硫（HCl—Soluble—S）含量分别增加0.4%，116.0%和50.1%，29.1%，而盐酸挥发性硫（HCl—Volatile—S）含量在R₂₀₀₂下降8.0%，在R₂₀₀₇增加19.7%。不同恢复阶段湿地土壤中各形态无机硫含量在生长季呈不同的变化特征，这一方面与不同湿地植物生长节律以及地上与地下之间的硫养分供给关系密切相关；另一方面则与不同生态补水方式导致的环境因子，尤其是pH、EC和氮养分的变化有关。随着恢复年限的增加，湿地土壤的总无机硫（TIS）含量以及其占全硫（TS）含量的比例均呈降低趋势。湿地土壤的TIS储量整体随恢复年限的增加而降低，而这种降低主要取决于H₂O—S、Adsorbed—S和HCl—Soluble—S的贡献，且以H₂O—S占优（78%~80%）。研究发现，随着黄河口湿地的逐渐恢复以及每年冬季芦苇收割活动的进行，恢复湿地土壤中的无机硫养分逐渐趋于缺乏状态，长期来看将不利于维持湿地的稳定与健康。     

黄河未来输沙量态势及其适用性对策

[目的] 探索黄河输沙预测的新思路，预估黄河未来输沙态势与输沙量水平，为黄河流域生态治理规划提供参考。[方法] 结合黄河流域水土保持生态修复现状，采用单累积曲线法、滑动平均及频率分析方法，分析1950—2019年黄河主要来沙区间的实测输沙量变化特征及其未来态势。[结果] 1950—2019年黄河输沙量呈现阶梯式减少。1950—2019年黄河中游各站累积实测输沙量随时间的变化可用“左半抛物线”表征。黄河输沙量自1997年以来已进入相对稳定态势，目前已达企稳状态；黄河潼关站未来年输沙量在90%频率下为1.00×10⁸ t左右，在10%频率下为5.00×10⁸ t左右，未来多年平均输沙量为1.40×10⁸ t。[结论] 为了维持黄河输沙量低稳状态，提升水土保持措施质量与标准，补齐“后水土保持”短板，构建完善的水沙关系调控体系，维持黄河下游河道冲淤平衡，是黄河流域生态保护与高质量发展的保障。     

黄河三角洲不同土地利用类型土壤微观结构特征

黄河三角洲不同土地利用类型盐碱土微观结构的研究,对认识该地区盐碱土的工程性质和对滨海盐碱地治理具有重要意义。该研究结合粒度分析(particle size distribution,PSD)、X射线衍射(X-ray diffraction,XRD)、压汞(mercury intrusion porosimetry,MIP)和扫描电镜(scanning electron microscopy,SEM)方法,对3种不同土地利用类型盐碱土的微观结构进行定量分析,旨在揭示其微观特性,为黄河三角洲盐碱地治理提供微观理论依据。结果表明:不同土地利用类型下的土壤黏粒含量表现大小依次为农田、滩地、草地,而土壤孔隙度大小依次为草地、滩地、农田;农田、草地与滩地盐碱土矿物成分中,石英、方解石和钠长石等原生矿物占绝对优势,仅含少量黏土矿物,且农田黏土矿物含量远大于草地与滩地;草地与滩地盐碱土孔隙特征类似,两者在0.1≤孔隙直径<10μm范围内小孔隙与微孔隙占有绝对优势,而农田盐碱土以孔隙直径在<2μm范围内的微孔隙与超微孔隙为主。农田盐碱土由致密片状、扁平状结构与微裂隙构成,骨架颗粒间由黏土矿物胶结;草地盐碱土由紧密镶嵌的块状颗粒和架空孔隙构成,骨架颗粒间无胶结;滩地盐碱土由紧密堆积的粒状颗粒和粒间孔隙构成,骨架颗粒间无胶结。研究成果可提高对黄河三角洲不同土地利用类型盐碱土微观结构的认识,为滨海盐碱地的治理、利用和开发提供了微观尺度上的依据。     

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.     

331份四川小麦品种(系)在甘肃陇南抗条锈性表现及利用价值

2014年-2017年度先后对331份四川省小麦生产品种(系)在温室进行苗期人工接种条锈菌混合菌鉴定和甘谷试验站大田成株期分别接种CYR32、CYR33、CYR34、G22-14、中4-1和混合菌鉴定,同时在甘谷试验站和汪川良种场两地进行自然诱发鉴定。结果发现:在人工接种条件下,苗期、成株期表现抗病的分别有‘XK201465’等36份和‘XK20132’等72份材料,分别占10.88%和21.75%;有‘XK62483’等11份材料全生育期表现抗病,占3.32%;两地三年自然诱发鉴定发现,仅有‘XK20132’等5份材料在两地均表现抗病,有‘川农17’等30份材料具有慢条锈性。对供鉴材料在甘肃陇南的利用前景进行了分析。     

1969-2018年黄河实测径流与天然径流的变化

[目的] 分析黄河实测径流与天然径流的变化规律，为探究人类活动对径流的影响提供依据。[方法] 基于1969—2018年黄河干流8个水文站的天然径流和实测径流数据，使用Mann-Kendall趋势检验与突变检验法，对比分析近50 a黄河干流实测径流和天然径流的变化规律。并结合近15 a各分区耗水数据探讨人类活动对于径流的影响。[结果] ①1969—2018年黄河上中下游实测径流整体呈降低趋势，兰州、花园口、利津3个代表站多年平均降低速率分别为5.10×10⁷，3.55×10⁸，4.13×10⁸ m³/a。②近50 a天然径流和实测径流趋势突变主要集中在1986和1990两个年份，结合前人研究和重要水事分析，1986年突变可能与1984年以来一系列水土保持措施实施以及1986年龙羊峡水库修建有关；而造成1990年径流突变的原因可能是80—90年代黄河流域用水量激增和流域下垫面改变。③天然径流与实测径流的差值从上游至下游水文站断面逐渐增大，这主要与近15 a平均耗水量也沿程增大相一致；另外多年平均实测径流在利津站仅占天然径流的42%。耗水量最大的两个分区为花园口以下和兰州—头道拐段，分别达到了1.06×10¹⁰和1.04×10¹⁰ m³。[结论] 人类活动中的各项耗水（尤其是农田灌溉）是造成兰州站以下地区天然径流与实测径流差值大的主要原因，因此，应进一步推进黄河流域节水农业的发展，合理分配各项耗水量。     

Regional and temporal differentiation of virulence phenotypes of Puccinia triticina from common wheat in Russia during the period 2001–2018

Leaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north-west and south-west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.     

桑树赤锈病的发生与防治

调查广西宜州市桑树赤锈病发生状况,分析桑树赤锈病发生特点及规律,针对宜州市桑树赤锈病大面积发生状况,提出有效地防治措施。     

芝麻黄化突变体YL1的叶片解剖学及光合特性

表型性状标记在作物遗传育种中具有重要的应用价值。在芝麻地方种质"庙前芝麻"中发现了能够稳定遗传的黄化突变体YL1,对该突变体的叶片解剖特征、光合特性及农艺性状的比较分析表明,突变体YL1黄化心叶和平展叶在各个发育时期的叶绿体结构均与同时期野生型存在明显差异,下表皮气孔保卫细胞数是正常叶的2倍左右。YL1的叶绿素a、总叶绿素、类胡萝卜素含量均只有同时期正常含量的30%~40%,叶绿素b含量只有正常叶的20%;光合速率在初花期及以前均显著低于同期正常叶,但到终花期与正常叶相当;YL1的生育期和初花期显著推迟,株高和单株蒴果数明显降低,每蒴粒数和千粒重略微降低。显微观察表明,YL1的叶绿体形态结构发育不规则,基粒和基粒片层数目明显少于野生型,使得叶绿素含量过低,属于叶绿体发育异常导致的叶绿素缺少型突变体。