马齿苋种子催芽试验结果初报

马齿苋种子具有休眠特性,在自然条件下发芽率低、发芽速度慢,对其开发利用产生了很大阻碍。通过低温层积和GA3两种方法分别对其进行了催芽实验,结果表明:经过8周的低温层积和600mg/L的GA3处理可有效破除休眠,使其发芽率达到最高水平,并提高了发芽的整齐度。     

打破长白楤木种子休眠方法的研究

长白楤木（Aralia continentalis Kitagwa）种子具有休眠特性,自然条件下萌发困难,试验采用温度和药剂处理的方法研究打破长白楤木种子休眠促进萌发的方法.试验结果表明：变温处理比恒温处理更有利于长白楤木种子的萌发.在变温处理的条件下,GA3可以有效的提高长白楤木种子的发芽率和发芽势,在试验范围内其发芽率与发芽势随着处理浓度的增大而升高.     

山桃种子内源激素在休眠萌发期间的变化 (Ⅰ)ABA和IAA(英文)

为了比较全面地了解需低温种子休眠和萌发的激素控制机理,我们以室温贮藏为对照,系统研究了低温和外源植物生长调节物对山桃种子萌发的影响,并用气相色谱和气相色谱—质谱联用仪分别测定了内源ABA和IAA在不同贮藏条件下的变化。研究发现:山桃种子去除种皮、子叶后的离体胚轴是不休眠的,在整个室温贮藏期间,种皮对萌发均有显著的抑制作用。去除种皮即可使贮前山桃种子的萌发率由0提高到40％。如果不去除种皮而仅在胚根处划破种皮,可使萌发率提高到26％左右。所以,种皮的抑制作用肯定有一部分是抑制物质引起的。分析证明,种皮ABA含量在贮藏前高达690.07ng/g·FW。干藏16周后仅下降到616.47ng/g·FW。对萌发的抑制作用仍保持原有水平。低温层积6周,种皮ABA含量下降到374.08ng/g·FW,对萌发的抑制作用未见明显减小。到第10周下降为183.74ng/g·FW,种皮对萌发的抑制作用完全解除。去除种皮后,仍有60％的种子不能萌发,而离体胚轴是完全能够迅速萌发的。所以,贮前来自子叶的抑制作用是相当强的。胚的ABA含量在贮前为303.82ng/g·FW,由于子叶比种皮重得多,所以ABA的总含量相当可观。加之子叶与胚之间的直接解剖结构联系,子叶的抑制作用要大于种皮。无论在室温或低温条件下,种子ABA含量均有下降。低温层积6周时,?     

过鱼设施进口区域水温对集诱鱼效果的影响

库区水温分层与过鱼通道隔断是水利水电工程建设随之产生的生态环境影响之一。过鱼效果是评估过鱼设施建设成功与否的关键指标。对于存在水温分层的高坝工程而言,过鱼设施进口附近存在的温差效应是否会对进口区域的集诱鱼效果产生影响是当前应该解决的首要问题之一。该研究通过建立三维水温水动力数学模型与包含过鱼设施进口段和明渠河流段的物理模型,分别开展了水温水动力预测及实鱼过鱼试验研究工作,研究结果表明：温差效应对进口附近水动力条件影响甚微,影响区域主要取决于鱼道流量,而岸边水温量值则取决于温差的大小;增大明渠流量将增加上溯鱼类发现鱼道进口的难度;沿冷水区域上溯样本量占总样本的39%,沿温水区域上溯样本量占总样本的61%,由此可知,温水区域对洄游鱼类更具有吸引力;温差效应在一定程度上有利于洄游鱼类发现鱼道进口并在进口区域聚集,与冷水区域相比,温水有效区域鱼进入鱼道进口的尝试率提高了17个百分点。研究成果可为相关人员尝试采用改变水温调整洄游鱼类上溯路线,改善鱼道进口集诱鱼,进而提升鱼道过鱼效果提供思路。     

面向省级农作物种植面积遥感估算的分层方法

针对当前遥感抽样估算中分层标志缺乏遥感识别误差描述的问题,该文探讨了基于农作物遥感识别结果的不同分层方法的抽样效率。以江苏省为研究区,采用2阶段分层,采用数字高程模型(digital elevation model,DEM)标准差进行一阶段分层,在一阶段分层的基础上,分别采用农作物识别种植规模、遥感识别破碎度、种植结构以及种植结构与破碎度指标进行二阶段分层。试验结果表明:种植结构与破碎度指标的分层效率最高,相对效率达到5.90,该分层指标融合了遥感分类结果反演出的种植结构和破碎度,不但能够有效地反映出农作物区域的景观特征,同时也较为合理地反映出区域间作物种植的差异性,为提高省级农作物种植面积遥感抽样估算效率提供有力的参考。     

Water quality fluctuations under floating net cages for fish culture in Lake Cirata and its impact on fish survival

ABSTRACT:   Vertical profiles of water quality were surveyed before and after mass mortality of fish cultured in cages in Lake Cirata, a man made lake in Indonesia. The first survey was performed 4 months before the mass mortality and the second survey was carried out 4 days after the mass mortality. In the first survey, the conditions below 8 m depth were reductive and anoxic, although at 8 and 10 m depth, the water became oxidative in spite of low oxygen concentration in the second survey. These changes were probably caused by strong mixing of surface water with deeper water. Eight months after the mass mortality, when the redox potential at 8 m became reductive again, exposure tests of fish were performed in different layers in the water column around the cage. During the exposure tests the redox potential of the water was less than −100 mV and 93% of carp died within 6 h of exposure at 8 m depth. These results indicated that the mass mortality was caused by the strong mixing of surface water with reductive water in deeper layers.     

Micronutrient Contents of a Revegetated Saprolite Exposed by Excavation of an Oxisol

Soils of the Brazilian Cerrado biome have been found to be deficient in copper (Cu) and zinc (Zn). In this area, an Oxisol was deeply excavated in 1962 during the construction of a hydroelectrical plant, and the exposed saprolite material was abandoned, without any reclamation measures. The abandoned land was a harsh environment for plant growth, and the secondary vegetation has not recovered. A field trial was established in 1992 to assess the effects of different grass species and lime amendments on soil reclamation at the degraded site. In 2011 soil samples were collected at three depths (0–10, 10–20, and 20–40 cm) from vegetated and bare plots over tilled saprolite, from an untreated area of the saprolite, and from an Oxisol under native forest, used as external reference. Nineteen years after the reclamation effort was begun, the organic carbon (OC) content of the restored saprolite still was much lower than that of the Oxisol under natural vegetation. The undisturbed Oxisol was deficient in extractable Cu (0.16–0.10 mg kg^?1) and Zn (0.10–0.02 mg kg^?1) and exhibited rather low concentrations of extractable iron (Fe; 5.24–1.47 mg kg^?1) and manganese (Mn; 3.21–0.77 mg kg^?1). However, the saprolite under reclamation showed even lower levels of these elements compared to the native forest soil. In the natural soil, OC, N, extractable Fe, Mn, and Cu showed stratification, but this was not the case for extractable Zn. Although the reclaimed saprolite still was far from predisturbance conditions, the revegetation treatments promoted recovery of OC, N, Fe, Mn, and Cu at the surface layers, which resulted in incipient stratification. Extractable Fe, Mn, and Cu were correlated to OC, whereas no association between Zn and OC was detected. Our results also suggest that reclamation of the excavated saprolite may be constrained by micronutrient deficiencies and mostly by the extremely low levels of Zn and Cu.     

分析模拟土壤压实对陆稻根系生长的影响

为研究土壤压实对陆稻根系生长的胁迫作用,关键是确定土壤中陆稻根系生长的参数变化。制作水─土分层装置便于统计根系穿出土壤层的时间,从而比较出土壤压实对根系轴向生长速度的影响。基于Visual C++6.0开发环境和Open G L图形库对土壤压实下,陆稻根系进行可视化模拟,为研究不同土壤压实对植物根系生长的影响提供了一种新方法。     

基于最小限制水分范围评价不同耕作方式对土壤有机碳的影响

以2009年吉林省德惠市中层黑土上进行了8a的田间定位试验小区土壤为研究对象,对免耕和秋翻两种耕作方式及玉米-大豆轮作和玉米连作两种种植方式下耕层有机碳进行分析,分别采用加权平均和分层两种方法计算最小限制水分范围(LLWR),用其评价不同耕作方式对土壤有机碳的影响.结果表明,免耕在玉米-大豆轮作和玉米连作下0-5 cm土壤有机碳含量分别比秋翻增加了15.2％和11.5％ (P＜0.05).采用加权平均法计算的LLWR值为0.148-0.166 cm3/cm3,不同耕作方式下玉米-大豆轮作的LLWR高于玉米连作且在两种种植方式下均表现出免耕小于秋翻的特点;利用分层法计算得到的LLWR值介于0.130-0.173 cm3/cm3之间,玉米-大豆轮作和玉米连作下免耕0-5 cm LLWR均显著小于秋翻,而5-30 cm LLWR数值免耕大于秋翻(P＞0.05);玉米-大豆轮作下0-30 cm各层LLWR均高于玉米连作.由于LLWR可以评价不同耕作方式对土壤有机碳的影响,因此采用加权平均法计算的LLWR可以客观的反映不同耕作处理尤其是种植方式对土壤有机碳的影响;而采用分层法计算的LLWR则更清晰的刻画了土壤表层与亚表层固碳能力的差异.     

保护性耕作对太行山前平原土壤热水解和酸解有机碳的影响

【目的】研究传统耕作转为保护性耕作后土壤热水解碳（HWC）和酸解碳（AHC）的分布和积累特征。【方法】2001年在河北栾城设置翻耕+玉米秸秆不还田（CK）、翻耕+玉米秸秆粉碎还田（CT）、旋耕+玉米秸秆粉碎还田（RT）和免耕玉米秸秆直立还田（NT）4个处理。2007年小麦收获后,采集0—5 cm、5—10 cm、10—20 cm和20—30 cm土层样品,测定热水解有机碳（HWC,80℃水浴下提取24 h）和酸解有机碳（AHC,6 mol•L-1 HCl,105℃下提取4 h）的浓度,分析两种活性碳的层化比率值（SR）,并基于等效质量碳库储量计算方法,比较了不同耕作处理对土壤活性碳分布和储量的影响。【结果】连续6年保护性耕作后,HWC和AHC在土壤表层积累,具有较高的层化比率值。在0—10 cm土层,保护性耕作（RT和NT）系统HWC的SR值（1.68—1.98）显著高于传统翻耕（CK和CT）处理（1.30—1.50）,保护性耕作下AHC的SR值（1.62—1.83）亦高于传统翻耕（1.12—1.63）。与传统翻耕CT相比,保护性耕作系统0—30 cm剖面的HWC储量无显著变化,但免耕显著增加了AHC的储量。【结论】在太行山前平原地区,保护性耕作导致土壤剖面中HWC和AHC在表层积累,呈现高度层化特征,可能会潜在影响土壤质量和农田固碳速率。