不同西兰花品种与硒肥浓度对硒富集的影响

为了研究不同西兰花品种、硒肥浓度对硒富集的影响,对硒富集量较高的西兰花品种进行了筛选,并在不同西兰花品种、不同硒肥浓度条件下,测定了不同处理的硒元素含量。结果表明:绿天使2号品种较其他品种具有优质、高产、硒元素含量高的特点,应用富硒叶力肥较不施肥的品种硒元素含量高,667 m~2喷施浓度以0.140%最佳,喷施硒肥后产量、硒元素含量较高。     

棉秆隔层对土壤水分入渗及水盐分布的影响研究

采用室内土柱实验,研究了裸地、棉秆隔层表层放置、棉秆隔层15cm、30cm、45cm和60cm处放置6个处理的土壤入渗特征及入渗后土壤水盐分布,以期对盐碱地改良提供依据。结果表明：棉秆隔层的设置降低了土壤入渗速率和累积入渗量,有利于棉秆隔层以上盐分的淋洗；秸秆隔层的设置降低土壤水分的蒸发,有利于隔层以下土壤水分的保持；各处理盐分均出现表聚,其中秸秆表层覆盖盐分表聚最小。     

Evaluating the relationship between yearling walleye,Sander vitreus,electrofishing catch‐per‐unit‐effort and density in northern Wisconsin lakes

Recruitment declines of walleye, Sander vitreus (Mitchill), observed in some northern Wisconsin lakes have resulted in management actions to evaluate and rehabilitate populations. An effective index for estimating relative abundance of yearling walleye is required. The objectives herein were : (a) to evaluate the relationship between yearling walleye electrofishing CPUE and density in northern Wisconsin lakes; (b) to test for the influence of lake‐specific factors on electrofishing catchability of yearling walleye; and (c) to develop an index whereby electrofishing CPUE can be used to quantify yearling walleye relative abundance. Yearling density was significantly positively related to electrofishing CPUE on a long‐term dataset from Escanaba Lake as well as a dataset including several lakes combined. Electrofishing catchability of yearling walleye was negatively related to lake‐surface area but was not related to other lake‐specific variables. This index can provide an efficient method to continue monitoring natural recruitment and also to evaluate survival of stocked walleye.     

不同混施钝化剂对水稻吸收累积Cd的影响

将石灰、赤泥和高岭土按不同比例混合(施用总量为4500kg hm-2)施加于Cd污染稻田土壤,根据混合比例不同设置CK(常规种植)、T1(1∶7∶4)、T2(3∶5∶4)、T3(4∶4∶4)和T4(6∶2∶4)共5个处理,探究不同混施钝化剂对水稻吸收累积Cd的影响。结果表明:4种混施处理能够显著降低土壤有效态Cd含量,较CK相比依次降低了28.0%、40.9%、43.4%和57.4%。4种混施处理能够不同程度地降低水稻各部位对Cd的吸收累积,籽粒的Cd含量依次降低47.1%、49.2%、55.5%和81.6%,T2、T3和T4处理水稻籽粒中Cd含量达到了食品安全国家标准(G B27622017,Cd≤0.2mg kg-1)。土壤有效态Cd含量与水稻根、茎、叶和籽粒中Cd含量的Pearson相关系数分别为0.826、0.709、0.778和0.532,均达到显著相关。不同处理根系富集系数依次为5.03、1.83、2.22、1.32和0.90,钝化处理显著降低了水稻根系对Cd的富集能力。各处理水稻产量以及籽粒K、Mg元素含量没有显著差异,T1到T4处理Ca元素含量依次增加。综合分析,T4处理对于降低土壤中有效态Cd含量以及水稻籽粒中Cd含量效果最佳,且没有降低水稻产量和与稻米品质密切相关的K、Mg和Ca元素含量。     

起垄沟播和常规平播下滴灌棉田土壤水盐的运移

为明确滴灌条件下植棉方式对土壤水盐运移的影响，采用田间调查与室内分析相结合的方法，在滨海重度盐碱地开展了起垄沟播和常规平播植棉方式下的水盐运移试验，调查了滴灌前后两种植棉方式不同点位及不同土壤深度的土壤水分、盐分和土壤溶液电导率等指标，分析不同植棉方式土壤水分、盐分和土壤溶液电导率的时空分布特征。结果表明：滴灌条件下起垄沟播的水分入渗深度和盐分淋洗深度均明显大于常规平播植棉方式，起垄沟播植棉膜下(0~20 cm)土壤溶液电导率明显低于常规平播植棉；滴灌对两种种植方式膜外土壤水分和盐分运移未产生明显影响。起垄沟播联合滴灌技术更有利于为棉花生长的水盐环境。研究结果可为盐碱地植棉提供理论参考和实践依据。     

Challenges for the sustainable use of water and land resources under a changing climate and increasing salinization in the Jizzakh irrigation zone of Uzbekistan

Jizzakh Province in Uzbekistan is one of the largest irrigated areas in Central Asia without natural drainage.In combination with aridity,climate change and extensive irrigation practices,this has led to the widespread salinization of agricultural land.The aim of this study was to identify opportunities to improve the reclamation status of the irrigated area and how best to effectively use the water resources in Jizzakh Province based on investigations conducted between 1995 and 2016.A database of field measurements of groundwater levels,mineralization and soil salinity conducted by the provincial Hydro-Geological Reclamation Expeditions was used in the study.The total groundwater mineralization was determined using a portable electric conductometer(Progress 1T)and the chloride concentration was determined using the Mohr method.The soil salinity analyses were conducted by applying two different methods:(1)the extraction and assessment of the soluble salt content,and(2)using an SM-138 conductivity sensor applied to a 1:1 mixture of soil sample and water.The analyses of the monitoring results and the salt balance in the"irrigation water–soil–drainage water"system clearly demonstrated that the condition of the irrigated land in the province was not significantly improved.Under these conditions,the stability of crop yields is achieved mainly through the use of large volumes of fertilizer.However,excess amounts of mineral fertilizers can also cause the salinization of soils.The average groundwater salinization value in most of the irrigated land(75.3%)fluctuated between 1.1 and 5.0 g/L,while the values were less than 1.0 g/L in 13.1%of the land and in the range of 5.1–10.0 g/L in 10.5%of the land.During the period of 1995–2016 the salinization level of the irrigated land in Jizzakh Province increased slightly and the area could be divided into the following classes:no salinity(17.7%of the total area),low salinity(51.3%),moderate salinity(29.0%),and high salinity(2.0%).Detailed studies of the salt balance in irrigated land,the impact of climate change,increased fertilizer use,and repeated remediation leaching on the groundwater level and mineralization should be conducted in the future,due to the possibility of accelerated salinization,fertility decline,and reduced yields of agricultural crops.     

干旱区平原水库坝后排水沟对下游农田土壤水盐运移的影响

干旱区平原水库的渗漏会抬高坝后农田地下水位,使土壤发生盐渍化,许多土地因此减产甚至弃耕。坝后设置排水沟是一种有效控制农田地下水位的措施。本研究采用排水沟调控坝后农田的地下水位,并利用HYDRUS模拟出在不同地下水位和深度的条件下土壤含水率与含盐量的变化情况,将实测数据与模拟数据相互对比,检验出模拟值的可靠度。研究结果表明:地下水位通过排水沟从1 m降到3 m,表层含盐量相差1.49～33.19 g·L~(-1),因此排水沟遏制地下水位越深,水盐运移越不明显,次生盐渍化越不容易发生,反之,则容易发生土壤盐渍化;地下水位相同时,土体种植植物可以降低含水率和含盐量,其中含水率最大变化为6.33%,含盐量仅相差0.08～4.56 g·L~(-1)左右,而且随着土层深度增加其影响的程度也逐渐减小。设置排水沟是解决坝后农田土壤盐渍化的较好方式。     

基于VOF模型的高温熔盐泵上端密封泄漏分析

为研究熔盐泵上端间隙密封的运行性能,基于SST k-ω湍流模型和VOF模型对熔盐泵上端密封结构性能进行计算,对不同扬程和不同介质条件下的泄漏量、扬程损失以及溢液腔内气液交界面形态进行分析.讨论扬程和介质条件对上端密封性能的影响,总结了关键变量和上端密封性能之间的相关关系.结果显示:泵扬程的增大会使泄漏量增加,如果扬程过大,黏性会对泄漏量产生显著影响;在相同扬程条件下,4种介质在间隙密封进出口的扬程损失差异均很小;间隙扬程损失随着泵扬程的增大而增加,3种泵扬程条件下间隙扬程损失都稍小于泵扬程;在溢液腔中,轴壁面高速旋转会使液体形成不规则的气液交界面和空腔;泵扬程的增大会抬高气液交界面的最高位置,使排液口内充液更多;在清水介质条件下,对该上端密封在不同扬程和流量的泵中下进行测试,在最高压力工况下熔盐泵仍保持稳定运行,未出现严重泄漏.     

水盐胁迫下根系提水作用对土壤盐分与番茄产量的影响

为探究水盐胁迫下番茄根系发生提水作用的可能性及其对土壤盐分分布和番茄产量的影响,利用上下桶分根装置,设定上桶不同水分(W1、W2、W3表示土壤含水率为田间持水率的60%～70%、50%～60%、40%～50%)和盐分条件(S0、S1、S2表示Na Cl添加量分别为干土质量的0、0.2%、0.4%),监测分析了水盐胁迫下根系提水量、上桶盐分分布及番茄产量。结果表明:随着生育期的推进,根系提水量呈现先增加后减小的趋势,其中盐分对番茄根系提水量影响显著,在相同水分处理条件下,盐分含量越高,根系提水量越大;水盐胁迫下,上桶盐分含量与根系提水量呈线性正相关,除W1S0处理外,上桶土壤电导率在提水量达到最大时有所增加;与对照处理W1S0相比,水盐抑制了根系生长,使根系活性显著下降,同一水分处理下,随着盐分的增加,根长、根表面积及根体积减小;盐分对番茄水分生产率有显著影响,在相同水分条件下,盐分越大,水分生产率越大,7种处理中W2S2水分生产率达到最大,而其产量较对照并未显著减小,生育期提水量占需水量的17.73%。本研究对进一步理解作物在"上干下湿"的土壤水盐胁迫下充分利用土壤剖面深层水分来维持上层根系生存和提高水分生产率具有科学价值。     

微咸水膜下滴灌对土壤水盐分布及加工番茄产量的影响

为探明微咸水膜下滴灌对土壤水盐分布及加工番茄生长和产量的影响,通过大田小区试验,设置灌水矿化度和灌水定额两个因素,其中3个灌溉水矿化度水平分别为S1:1 g·L~(-1)、S2:3 g·L~(-1)和S3:5 g·L~(-1),3个灌水定额分别为W1:305 m~3·hm~(-2)、W2:458 m~3·hm~(-2)和W3:611 m~3·hm~(-2),来进一步寻求适宜本地区加工番茄生长的微咸水膜下滴灌灌溉制度。结果表明:覆膜微咸水滴灌条件下土壤含水量垂直方向的变化趋势表现为0～20 cm土层随深度增加含水量逐渐降低、20～100 cm土层随深度增加含水量逐渐增大、60～100 cm范围内土层剖面含水量最大的分布规律;土壤含盐量随着灌水矿化度的增大而增加,且随着灌水量的增加土壤盐分逐渐向水平距滴灌带35 cm处聚集。灌水矿化度超过3 g·L~(-1)时加工番茄株高、茎粗均受到一定程度的抑制作用,但对产量影响不大。本文通过试验得出:灌水定额为611 m~3·hm~(-2)、矿化度为1 g·L~(-1)处理为本地区最佳微咸水膜下滴灌处理,加工番茄生长健壮且产量最高,达到127 613.2 kg·hm~(-2);同时认为,在我国淡水资源比较缺乏的新疆地区可以考虑采用灌水定额458 m~3·hm~(-2)和灌水矿化度3～5 g·L~(-1)的微咸水对盐分中等敏感的加工番茄进行灌溉。