高原气候下西藏不同熟期甘蓝型春油菜光温资源利用效率比较分析

为了充分协调产量潜力与气候资源高效利用的关系,研究高原气候下不同熟期甘蓝型春油菜的光温利用效率,选用3个不同熟期甘蓝型春油菜品系,设置4个播期,分析不同播期下西藏甘蓝型春油菜的生长发育及产量形成规律。结果表明：随着播期的推迟,参试油菜生育期间的温度升高,达到有效积温的天数较少,参试油菜生育期缩短;其中苗期、蕾薹期和花期较早播呈缩短趋势,角果成熟期有延长趋势。晚播油菜的茎秆伸长期雨热充足,参试油菜的株高较早播有增加,而茎粗有降低;晚播造成参试油菜前期营养生长不足,成熟期干物质积累较早播下降。晚播油菜生育后期遇持续降雨造成成熟期油菜的有效分枝数、单株有效角果数和单株粒重的降低,较早播油菜明显减产。播期改变了参试油菜的光、温利用效率,早熟品系NY16在B2播期（2021年3月15日）下光、温利用效率较高,分别为0.081 g·MJ^-1和1.017 kg·hm^-2·℃^-1;中熟品系NY28和晚熟品系NY52均在B1播期（2021年3月8日）下光、温利用效率较高,分别为0.1 g·MJ^-1 、1.282 kg·hm^-2·℃^-1和0.134 g·MJ^-1、1.712 kg·hm^-2·℃^-1。同一播期下中晚熟品系的光、温利用效率大于早熟品系。因此,适时早播可促进甘蓝型春油菜光温利用效率的提高,促进产量形成,早熟品系在3月15-22日,中晚熟品系在3月8-15日播种适宜。西藏一年一熟种植制度下,为充分协调生态条件与生产潜力关系,一定无霜期范围内,中晚熟品系的选育和利用可有效提高甘蓝型春油菜产量。     

春小麦航天育种效果的研究

将小麦纯系种子用硼酸溶液和水浸泡后进行航天诱变处理。研究表明 ,航天处理对种子发芽、出苗和生长有明显的促进作用 ,第 2代农艺性状具有广泛变异 ,而且正向变异较多 ,为后代选择提供了更多机遇。选出了 5个高产、抗病、优质的小麦新品系 ,其中 97- 5 1 99已进入生产试验     

Small Scale Heterogeneity of Soil Chemical Properties: Effects on Spring Water Chemistry

Previous soil and spring water analyses in small catchments revealed low pH values in the spring water during high discharge events. This paper analyses the potential which small scale heterogeneity of soil acidity may have to explain decreasing spring water pH as a result of high discharge. Soil aggregates were collected from a C‐horizon of a Spodosol in the Fichtelgebirge. Exchangeable cations and soil solution were examined on both samples from the surfaces and the cores of aggregates which were obtained by a mechanical separation procedure. The Reuss‐Johnson soil chemical equilibrium model was used to predict soil and spring water pH values as a function of acidic input and soil air CO₂ concentration in equilibrium with both aggregate fractions. Ranges of acidic input from 160—570 μeq L⁻¹ and soil air CO₂ concentrations from 0.1 to 3 Vol. % were considered. The model predicted spring water pH values from 5.0 to 5.3 for the acidic aggregate surface samples (base saturation = 12.5%) and from 6.8 to 7.2 for the aggregate core samples (base saturation = 32.1%). The results suggest that small scale acidity gradients may expand the range of predictable spring water pH values. However, very low pH values (<5) still need additional explanation.     

First detection of spring viraemia of carp virus in common carp (Cyprinus carpio L.) affected by a septicaemic disease in Mexico

Spring viraemia of carp (SVC) is an infectious disease responsible for severe economic losses for various cyprinid species, particularly common carp (Cyprinus carpio carpio). The causative agent is the SVC virus (SVCV), a member of the Sprivivirus genus, Rhabdoviridae family, and a List 1 pathogen notifiable by the World Organization for Animal Health. This study describes the diagnosis of an SVCV pathogen isolated in October 2015 from wild common carp inhabiting a natural lagoon in central Mexico. While neither an epidemic nor fish mortalities were reported, the collected killed specimens exhibited clinical signs of disease (e.g., exopthalmia, moderate abdominal distension and haemorrhaging, as well as internal haemorrhages and adhesions). Histological results of injuries were consistent with the pathology caused by SVCV. This finding was supported by the isolation of a virus in EPC and BF‐2 cells and subsequent RT‐PCR confirmation of SVCV. The phylogenetic analyses of partial SVCV glycoprotein gene sequences classified the isolates into the Ia genogroup. These findings make this the first report of SVCV detection in Mexico, extending the southern geographical range of SVCV within North America. However, since this pathogen was detected in fish inhabiting a natural body of water without tributaries or effluents, it is difficult to estimate the risk of SVCV for other wild/feral cohabitating cyprinid species in the lagoon. The status of this virus is also unknown for other bodies of water within this region.     

Long‐term trends and drivers of larval phenology and abundance of dominant brachyuran crabs in the Gulf of St. Lawrence (Canada)

Climate change has led to major shifts in the timing of biological events, with many studies demonstrating earlier phenology in response to warming. However, few of these studies have investigated the effects of climate change on the phenology of larvae in marine species. Phenological shifts can result in mismatches between consumers and prey and hence affect growth and survival of individuals, and ultimately population demography. We investigated the temporal changes in phenology and abundance of the larvae of dominant brachyuran crabs in the southern Gulf of St. Lawrence (eastern Canada) based on plankton collections spanning 1982–2012. The Gulf of St. Lawrence has warmed since the early 1990s, and our analyses revealed that larvae of snow crab (Chionoecetes opilio) and toad crabs (Hyas spp.) exhibited a significant trend towards earlier phenology over the 30‐year study period. This shift in phenology appeared to be a consequence of the effect of climate warming on both the timing of hatching and larval development rate. Larval abundance responded differently by crab taxon to climate warming, likely due to differences in thermal tolerance. The warming trend was unfavourable to snow crab, which is the most cold‐adapted and stenothermic of the taxa examined in this study. The abundance of snow crab larvae was lower when sea ice retreat occurred earlier than day 110 of the year and sea surface temperature was higher than 8.5°C. On the other hand, larval abundance of rock crab (Cancer irroratus), which prefers higher temperatures, was positively related to surface temperature.     

燕山丘陵区锌肥不同施用方式对春玉米穗部性状及产量的影响

通过两年田间试验,以京单128玉米品种为材料,通过3种锌肥施用方式[底施锌肥(DS)、冲施锌肥(CS)、喷施锌肥(PS)]研究了不同锌肥施用方式对燕山丘陵区春玉米穗部性状、产量及籽粒含锌量的影响。试验结果表明,增施锌肥能够显著提高春玉米产量,不同锌肥施用方式增产效果表现为PSCSDSCK,平均增产率分别为15.2%、12.0%和5.4%。增施锌肥后穗长、穗粗、行粒数、百粒重呈增加趋势,禿尖长呈明显降低趋势,其中禿尖长和行粒数变异明显,变异系数分别为55.2%和6.8%,说明增施锌肥主要是通过降低果穗禿尖、增加行粒数来增加穗粒数,从而增加产量。同时增施锌肥能够显著增加玉米籽粒锌含量,施用效果也表现为PSCSDSCK,平均增幅分别为50.4%、36.9%和30.8%。由此认为,在典型缺锌地区的燕山丘陵区种植玉米时增施锌肥是增加玉米产量,改善产品品质的重要途径,在施用方式上以喷施最佳,冲施次之。     

南昌梨瓜早春不同基质配方育苗比较试验

为促进南昌梨瓜种苗业发展,筛选出适于南昌梨瓜培育壮苗的合适基质配方,选用当地常栽品种南昌梨瓜作为育苗对象,自主配制3组基质配方(草炭:蛭石:有机肥=3:1:1,草炭:珍珠岩:有机肥=3:1:1和草炭:蛭石:有机肥=7:2:1,质量比),以市面所售成品育苗基质为对照,通过对比成苗各项指标,结果得出配方1(草炭:蛭石:有机肥=3:1:1)培育的种苗长势好,叶色浓绿,根系嫩白、密集,基质和根系缠绕紧密,根坨完整,符合壮苗标准,适于南昌梨瓜早春穴盘基质培育壮苗。     

青海高原地区春小麦品种田间化感作用评价

为明确青海高原地区不同春小麦品种对麦田主要危害杂草旱雀麦Bromus tectorum的化感作用,本研究通过田间一致性试 验对青海高原地区的20个春小麦品种(系)进行化感作用评价,筛选出强化感作用品种。分别于春小麦3～5叶期和成熟期调查受体旱雀麦的生长性状,转化为化感作用指数,并结合聚类分析,将20个小麦品种按化感作用的强弱分为强、中、弱３类。结果表明,20个春小麦品种(系)对受体旱雀麦的田间生长均具有化感抑制作用,其中‘青春38号’‘黑丝麦1号’‘通麦2号’和‘互麦11号’为田间化感作用较强的春小麦品种。该研究为青海高原地区春小麦化感抑草品种选育提供了新资源,同时为青海高原地区化学农药减量和生态环境保护提供了新策略。     

后簧座成形工艺设计与分析

提出了一种生产后簧座的工艺方法：拉深-多步缩口-成形。与传统的旋压成形比较,可较大地降低设备的投资,提高生产效率和产品质量,降低制造成本。对圆筒形零件缩口工艺方法进行了变形分析、试验与理论解析,确定了工艺优化的理论与试验方法,找到了合理的成形工艺方案,并成功应用于后簧座的生产。     

番茄色选机弹齿气缸的仿真研究

为研究一种新型弹齿气缸的工作特性,建立了气缸内部腔体动态特性微分方程组,利用Matlab中的四阶龙格—库塔法求解方程,得出气缸工作过程中腔室压力以及活塞位移、速度随时间变化的动态曲线。通过对曲线变化趋势进行理论分析,表明这种新型气缸对减小活塞冲击、快速复位、减少响应时间有明显作用。