2011-2020年夏季全国草原净初级生产力时空变化及其气象影响评估

为评估2011—2020年夏季全国草地净初级生产力时空变化以及气象条件对净初级生产力的影响,本研究依据气象站逐日气象观测资料以及中分辨率成像光谱(Moderate-resolution imaging spectroradiometer,MODIS)系列卫星资料遥感数据,分析了近10年夏季全国草地净初级生产力变化。结果表明:2011—2020年夏季全国草原净初级生产力总体呈现增加趋势,平均每年增加0.2 gC·m^-2·a^-1,内蒙古中部、甘肃东部、青海东部、西藏东部等地近10年草原净初级生产力明显增加。近10年全国大部草原区平均气温和降水量均呈增加趋势,较好的气象条件利于夏季牧草生长。2020年夏季全国草原区的气温和降水量也较常年偏高,北方草原区草地平均净初级生产力为121.3 gC·m^-2·夏季^-1,为近10年偏好年份。2011—2020年夏季全国草原净初级生产力呈增加趋势,较好的气象条件对其贡献较大。     

‘清水’苜蓿与‘WL168’杂交后代的表型特征及生理特性

本研究以‘清水’紫花苜蓿（Medicago sativa L.‘Qingshui’）与‘WL168’紫花苜蓿（Medicago sativa L.‘WL168’）的杂交后代选育系RSA-01,RSA-02和RSA-03为研究对象,于种植第5年对其表型特征及生理特性进行观测分析。结果表明：RSA-01,RSA-02地上生物量显著低于‘WL168’（P<0.05）,而RSA-03显著高于‘清水’;RSA-02,RSA-03茎粗显著高于‘清水’和‘WL168’,而茎叶比均低于‘清水’;各形态指标中,茎粗变异系数最小,且RSA-03值最小,为2.17%;通径分析表明,RSA-01,RSA-02和RSA-03的茎叶比、茎粗与其地上生物量的直接通径系数分别为-0.649和0.709,-0.700和0.422,-0.858和0.189,茎叶比、茎粗是影响地上生物量的关键因素;RSA-01,RSA-03的过氧化物酶活性显著低于‘清水’和‘WL168’。与亲本‘清水’相比,RSA-03的地上生物量和茎粗都具有显著的杂种优势,但其抗逆性减弱,该研究结果为后期产量改良及抗逆性研究提供理论依据。     

Rapidly quantitative detection of Nosema ceranae in honeybees using ultra-rapid real-time quantitative PCR

BackgroundThe microsporidian parasite Nosema ceranae is a global problem in honeybee populations and is known to cause winter mortality. A sensitive and rapid tool for stable quantitative detection is necessary to establish further research related to the diagnosis, prevention, and treatment of this pathogen.ObjectivesThe present study aimed to develop a quantitative method that incorporates ultra-rapid real-time quantitative polymerase chain reaction (UR-qPCR) for the rapid enumeration of N. ceranae in infected bees.MethodsA procedure for UR-qPCR detection of N. ceranae was developed, and the advantages of molecular detection were evaluated in comparison with microscopic enumeration.ResultsUR-qPCR was more sensitive than microscopic enumeration for detecting two copies of N. ceranae DNA and 24 spores per bee. Meanwhile, the limit of detection by microscopy was 2.40 × 10⁴ spores/bee, and the stable detection level was ≥ 2.40 × 10⁵ spores/bee. The results of N. ceranae calculations from the infected honeybees and purified spores by UR-qPCR showed that the DNA copy number was approximately 8-fold higher than the spore count. Additionally, honeybees infected with N. ceranae with 2.74 × 10⁴ copies of N. ceranae DNA were incapable of detection by microscopy. The results of quantitative analysis using UR-qPCR were accomplished within 20 min.ConclusionsUR-qPCR is expected to be the most rapid molecular method for Nosema detection and has been developed for diagnosing nosemosis at low levels of infection.     

部分地区猪细环病毒1型感染的流行情况调查

猪细环病毒1型是近年来发现的又一种环状DNA病毒,可能存在潜在致病作用。为了初步了解其流行情况,用PCR技术和ELISA技术对来自京津冀、华东与华南地区578头保育猪血清样品进行了检测。结果显示,猪细环病毒1型的核酸与抗体的猪场阳性率均为100%;核酸阳性率为73.88%,抗体阳性率为78.72%,二者之间无显著差异（P>0.05）。进一步分析发现,猪细环病毒1型的核酸阳性率和抗体阳性率都超过50%的猪场达到86.67%,都超过80%的占53.33%。调查结果表明,猪细环病毒1型感染在我国部分地区普遍流行,其在多数猪场的感染率很高。     

内蒙古贺兰山马鹿的种群数量及种群结构

为了掌握内蒙古贺兰山国家级自然保护区内马鹿(Cervus elaphus)的种群数量和种群结构,维护内蒙古贺兰山的生态平衡。于2017年11—12月,2018年4—6月、11—12月,2019年4—6月,在内蒙古贺兰山国家级自然保护区内,利用样线法对保护区内的马鹿进行调查,采用Distance R进行数据分析,估测种群数量和种群密度,并对种群结构进行探讨。研究发现,马鹿在2018年冬季种群数量最高约为2452(1678—3578)只,种群密度为3.705(2.539—5.048)只/km²,遇见率为1.943只/km。遇见率年际间变化不明显(F=0.12,P=0.986);混合群出现的次数最高,雄性群出现的次数最低,不同集群类型在不同季节的差异极显著(P<0.001);群大小在不同季节的差异不显著(P=0.132);雌雄比在不同季节中没有太大变化。     

Starch digestion rates in multiple samples of commonly used feed grains in diets for broiler chickens

In this study the starch digestion rates in broiler chickens from 18 samples of 5 commonly used feed grains (sorghum, wheat, maize, barley, triticale) were determined. The methodology to determine starch digestion rates in poultry is detailed herein. Starch digestion rates were not significantly different (P = 0.128) across the 18 feed grains, which reflects the wide variations that were observed within a given feedstuff. Nevertheless, starch digestion rates in broiler chickens offered wheat-based diets were significantly more rapid by 56.0% (0.117 versus 0.075 min⁻¹; P = 0.012) than their sorghum-based counterparts on the basis of a pair-wise comparison. In descending order, the following starch digestion rates were observed: wheat (0.117 min⁻¹), barley (0.104 min⁻¹), triticale (0.093 min⁻¹), maize (0.086 min⁻¹), sorghum (0.075 min⁻¹). The implications of these findings are discussed as they almost certainly have implications for poultry nutrition and the development of reduced crude protein diets for broiler chickens.     

牧草柳枝稷种子破休眠技术的研究

柳枝稷switchgrass (panicum virgatum)的种子属深度休眠。本文探索了后熟化(干藏),冷冻层化(湿润冷藏),磨擦,浸泡,以及植物生长调节剂GA和ABA对破除种子休眠的影响。     

湖南农业运输机械事故灰色关联分析

利用灰色系统理论方法,对湖南省1997～2002年的农业运输机械事故的影响因素进行了系统分析,分析计算结果是:拖拉机拥有量与事故起数的关联度最大;事故起数关联度最大的是机械故障;驾车3年以上的驾驶员是事故发生的高危人群。     

小型多功能底盘稻麦割晒机研究

针对贵州山区田块小而分散,提出设计稻麦割晒机时应采用适应多种田间作业需要的通用底盘。小型多功能底盘主要由多功能底盘、发动机、动力传动系统、操作手柄及前后连接支架组成,多功能底盘上安装前后连接支架,根据田间农作物作业需要,与通用底盘快速挂接,可完成旋耕整地、开沟起垄、播种施肥、灌水施药及稻麦割晒等作业。该底盘可构建多功能作业机组,扩大机具使用范围和利用率,解决丘陵山地小田块机械化收割问题。     

烟草田间起垄机作业适应性研究

对开沟式和盒式的1WG-6.3型自走式小型起垄机进行田间试验,并对其作业效益、作业效率及作业效果等指标进行测量及性能分析对比。结果表明:盒式起垄机每公顷平均油耗较低,作业效率较高,稳定性好,起垄效果较好,能满足烤烟种植起垄效果的农艺要求;开沟式起垄机能满足烤烟种植垄底宽、垄高的农艺要求,但不能满足烤烟种植垄基宽的农艺要求,且每公顷平均油耗较高,作业效率较低,稳定性较差,垄形一般。因此,盒式起垄机更能适应烟草田间起垄作业。