基于农作制分区的1985—2015年中国小麦生产时空变化

Comparing spatio-temporal variation characteristics of China’s wheat production, yield, sown area and yield-area-contribution in different farming zones in the past 30 years could help improving wheat planting layout and adjusting planting structure. Concentration index, rate of change, moving of gravity and resolution of yield-area-contribution were used to analyze spatio-temporal changes of China’s wheat production and yield-area-contribution based on county wheat production statistics including sown area, production and yield from 1985 to 2015. The wheat sown area decreased obviously in Northeast farming region, Northwest farming region and South farming region and increased rapidly in Huang-Huai-Hai farming region and Yangtze Plain farming region. In Huang-Huai-Hai farming region, the concentration indexes of Haihe Plain farming region, Huang-huai Plain farming region and Fenwei Basin farming region reached to 20.64%, 25.77%, and 21.65% respectively in 2015. Wheat production increased significantly by more than 48 milliontons in Huang-Huai-Hai farming region, and nearly 8 million tons Yangtze Plain farming region but decreased by more than 2.6 million tons in Northeast farming region. In Huang-Huai-Hai farming region, wheat production was concentrated in Haihe Plain farming region, Huang-huai Plain farming region and Yuxi Hill farming region. The average wheat yield continuously improved during the study period, Huang-Huai-Hai farming region and Northwest farming region had the yield increase up to 103.5 kg hm ^-2 and 92.9 kg hm ^-2 each year. Wheat yield in Yuxi Hill farming region, Fenwei Basin farming region and Haihe Plain farming region was relatively high in Huang-Huai-Hai farming region. The yield-reduced area was mainly caused by the decreasing of sown area, while the yield-area-contribution rate was different in yield-increased area. Yield-dominant counties were reduced, area-dominant counties were increased and yield-area-dominant counties were relatively steady. In production increased area, yield-dominant and yield-area-dominant counties were the main types in Huang-Huai-Hai Farming region, area-dominant and yield-area-dominant counties were the main types in Yangtze Plain farming region. Chinese wheat production was increasingly concentrated in Huang-Huai-Hai farming region which has high and rapid increase of wheat yield over the past three decades. Haihe Plain farming region, Huang-huai Plain farming region and Fenwei Basin farming region were the most concentrated areas in Huang-Huai-Hai farming region for wheat production during this period. Wheat yield and sown area jointly promoted the increase of wheat production in Huang-Huai-Hai farming region, wheat sown area was the crucial factor to increase wheat production in Yangtze Plain farming region, especially in the north of Jiangsu, Anhui province and greater part of Xinjiang.     

吉林省生猪生产水足迹时空分异及优化布局研究

生猪养殖是畜牧业的重要组成部分,其生产和发展对水资源需求及水环境污染影响较大。水足迹区别于传统的取水指标,既可用于核算畜牧业耗水量,也可用于衡量畜牧业产生的水污染。为了研究吉林省生猪生产和发展对水资源需求及水环境的影响,基于水足迹理论及核算方法,对2000-2016年生猪生产水足迹进行量化,分析其绿水足迹、蓝水足迹、灰水足迹及总水足迹的时间变化和空间分布特征。结果表明：2000-2016年吉林省生猪的总水足迹呈下降趋势,其中绿水足迹呈上升趋势,蓝水足迹和灰水足迹呈下降趋势；吉林省各县(市、区)生猪绿水足迹、蓝水足迹、灰水足迹和总水足迹的空间分布总体为中部地区最高、东部地区最低,地域差异明显。因此,吉林省生猪养殖应优化布局,中部地区生猪养殖应大力发展,东部地区适当增加,而西部地区需加以控制。     

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.     

Forest recovery after clear-cutting in Chinese pine(Pinus tabuliformis) plantations of North China

In Hebei Province of North China, forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine(Pinus tabuliformis). This study was aimed to demonstrate the dynamic characteristics of recruits during the natural recruitment. Both plot survey and the spatial point-pattern analysis were performed. Five developmental stages of natural recruitment were selected and studied, including 1 year before and 2, 5, 8, and 11 years after clear-cutting. Different slope aspects were also included. Natural recruitment was always dominated by Chinese pine with a proportion of higher than 90%. For plots of 1 year before clear-cutting on east-and north-facing slopes, recruit densities were 7886 and 5036 stems/hm2, the average heights were 0.78(±0.85) and 1.06(±1.15) m, and the average diameters at breast height(DBH) were 3.21(±1.38) and 2.91(±1.38) cm, respectively. After clear-cutting, recruit density was initially increased, then it was gradually declined with time; however, the variation of average DBH was contrary to that of recruit density. Both of them were no longer varied between 8 and 11 years after clear-cutting. The average height of recruits continued to increase after clear-cutting. For the plots of 11 years after clear-cutting on east-and north-facing slopes, average heights of recruits reached 2.00(±1.14) and 2.24(±1.20) m, respectively. The statuses of recruits on north-facing slopes were better than those on east-facing slopes after clear-cutting. Meanwhile, recruits on east-facing slopes were always aggregated at small scales, while spatial pattern of recruits varied with time on north-facing slopes. Moreover, forest was recovered more quickly by natural recruitment than by artificial afforestation after clear-cutting. The structural diversity was higher in naturally regenerated forests than in plantations of the same age. Our results demonstrated that clear-cutting of Chinese pine plantations recovered by natural recruitment has the potential to be an effective approach for establishing multifunctional forest.     

陇东旱塬区复种不同藜麦品种(系)的适应性初步评价

为分析不同藜麦品种(系)在陇东雨养地区夏播复种的生态适应性,以12个藜麦品种(系)为材料,对其物候期、农艺性状、经济性状、品质性状等指标进行考察,采用相关性分析、主成分分析和聚类分析法对其适应性进行综合评价。结果表明:供试的12个藜麦品种(系)除LY-2无法复种成熟外,其余的11个品种(系)均能完成生育期;对其19个性状进行相关性分析表明,单位面积籽粒产量与单株粒质量和千粒质量呈极显著正相关(P0.01),而与根倒率、茎倒率呈极显著负相关(P0.01);株高与千粒质量呈极显著正相关(P0.01),籽粒粗蛋白和淀粉分别与籽粒直径和千粒质量呈极显著正相关(P0.01);对其15个性状指标进行主成分分析和聚类分析,对提出的5个主成分累计贡献率达85.04%,根据综合得分,筛选出适应性最好、得分最高的2个品种(系)‘陇藜4号’和‘Q2’;聚类分析表明,11个藜麦品种(系)系统聚为3大类型,各品种(系)间性状与遗传距离方面存在较大差异,其中第三类产量最高,第二类有矮秆、早熟等特性,可根据生产需要和育种目标进行综合考虑。     

基于局部均衡模型的中国羊肉市场供需变动分析

对中国羊肉市场供需变动情况进行深入分析,并运用局部均衡模型探究中国羊肉市场供给与需求相互变动的主要原因,最后运用ARIMA模型预测方法对中国未来羊肉供需变化进行预测分析。研究结果表明,中国羊肉市场需求的满足以国内市场供给为主,2017年国内供需缺口为74.28万t,约是1994年的3.82倍,供需缺口有扩大倾向。上一期肉羊存栏量、肉羊胴体质量水平、羊肉市场价格均显著影响国内羊肉市场供给量;上一期人均消费量与收入水平是影响城镇与农村居民当期人均消费量的重要因素;国际羊肉价格对国内羊肉出口量产生显著正向影响。在未来一段时期内,中国羊肉产量将保持稳定增长,羊肉消费量进一步增加,预计到2030年达到843.03万t,羊肉进口量较大幅度提高,可一定程度弥补国内羊肉供需缺口。为此,一方面需通过技术与政策支持大力发展国内肉羊产业,另一方面也需积极开拓国际市场,加强贸易协作。     

玉米XYLPs基因家族表达模式及其蛋白结构分析

通过生物信息学的方法对玉米木质形成素类阿拉伯半乳糖蛋白(xylogen-like arabinogalactan proteins,XYLPs)基因家族的表达模式和蛋白结构进行了分析。ZmXYLPs基因家族成员在染色体上的分布具有一定的偏好性。基因复制事件不仅在基因家族成员数量的扩张和进化中发挥重要作用,同时还可能引起基因表达部位的扩张。根据ZmXYLPs蛋白结构特点,可将其分为两大类。其中仅ZmXYLP10/13/14蛋白存在N连接的糖修饰位点,其余ZmXYLPs蛋白均为O连接糖修饰位点。结果显示,玉米ZmXYLPs的生物学功能可能与其糖基侧链有关,并且其作用并不局限于维管组织发生过程,可能也参与生殖发育过程。     

基于微卫星亲权鉴定技术的短蛸性选择研究

为研究短蛸(Octopus ocellatus)的性选择行为，本研究利用14个多态性微卫星标记，对3个母本、176个子代及17个候选父本进行亲权鉴定，对3个家系中有子代和无子代雄蛸、子代比例高和子代比例低的雄蛸的各形态参数进行t检验，并对子代比例高和子代比例低的父本与母本的遗传相似性与遗传距离进行分析。结果显示，短蛸为多雌多雄的交配模式，为真正意义的雌性混交动物；雄蛸有无子代与其形态参数无相关性；子代比例与父本的形态大小参数无关，而与父母本的遗传相似性和遗传距离有关，父母本遗传相似性越高，遗传距离越小，后代比例越高。本研究为揭示短蛸交配前后的性选择机制提供了重要线索，也为海洋头足类动物的性选择机制研究提供了基础资料。     

鳜视觉和侧线感觉调控捕食行为的动态观察

鳜（Siniperca chuatsi）具有独特的捕食习性。为研究鳜捕食行为相关主要感觉——视觉和侧线感觉调控的捕食行为特征，利用高速摄像与感官抑制技术对鳜的独特捕食行为进行了分析，将实验鳜分为4组：G_C（对照组，视觉与侧线感觉均具备），G_V（只有视觉），G_L（只有侧线感觉）和G_DS（视觉、侧线感觉均不具备）4组。对各组鳜投喂饵料鱼，并利用高速摄像技术对单位时间内鳜的捕食行为进行动态观察与分析。结果表明，鳜在捕食行为中表现出5种捕食模式：直接攻击型、跟踪-弹射型、跟踪-偏移型、弹射型、偏移型，其中，直接攻击型、跟踪-弹射型、弹射型捕食模式主要由视觉控制，跟踪-偏移型、偏移型主要由侧线感觉控制。在视觉、侧线感觉均具备时优先利用视觉捕食，捕食行为趋于简化，相反，鳜仅利用侧线感觉捕食时，捕食行为变得复杂而多样；鳜在捕食时所表现出的各种捕食行为模式是其具有独特摄食习性的重要原因。上述研究为解读鳜特殊捕食行为的形成机制提供了重要资料。     

鸡传染性贫血病临床症状与诊断

鸡群感染传染性贫血病后通常表现翼部发炎或变蓝,鸡体苍白,软弱无力,全身出血,死亡率增加等症状,剖检典型病变为骨髓退色、贫血、淋巴器官萎缩等。该病可通过鸡与鸡直接接触传播,最可能的感染途径是呼吸道。该文主要从鸡传染性贫血病的病原、流行病学特点、临床症状、病理学变化、诊断等方面对鸡传染性贫血病进行论述。