提高商品猪出栏率的措施

不同品种杂交所得到的杂种猪，比纯种亲本具有较强的生活力，具有好喂养，生长快，抗病力强，育肥周期短等特点。试验结果证明，采用二元杂交猪，可比纯种猪提高日增重15％～20%，三元杂交猪比纯种猪提高25%左右。目前国内多采用长白和大约克的杂交母猪与杜洛克、皮特兰或汉普夏的公猪交配，从而获得最佳的三元杂交组合。     

妊娠母猪的饲养和营养需要

养好妊娠母猪的目的是保证胎儿的正常发育，防止流产和死胎。确保生产出头数多、初生重大、均匀一致和健康的仔猪，并使母猪保持中上等体况，为哺育仔猪做准备。     

再论图书馆对读者人文关怀的实现

现代网络信息技术的发展并不能影响“人文价值”在图书馆的核心价值地位。图书馆人文价值的重要内容是人文关怀,而其中对读者的人文关怀尤其重要。从满足读者的知识需求和关注读者的心理感受2个层面来论述图书馆对读者人文关怀的实现。     

河北省主推番茄品种抗黄化曲叶病鉴定与筛选初报

采用田间自然鉴定方法对河北省42个番茄生产主推品种进行抗番茄黄化曲叶病鉴定。结果表明,‘迪芬尼’、‘74 589’、‘佳西娜’、‘格利’、‘74 587’、‘荷兰6号’、‘Ty204’等7个品种田间表现明显抗番茄黄化曲叶病,发病率分别为0、0、0、1.35%、1.32%、0、1.76%。其余35个品种田间均表现明显感病,发病率最高的品种为‘鲁寿巨粉’,发病率达到99.22%,各品种发病率差异显著。     

河北坝上露地错季大白菜化肥农药减施增效栽培技术

露地大白菜化肥农药减施增效栽培模式集成集约化育苗，定植前药剂喷淋防病，生物防治，杀虫灯监测及诱杀，有机肥或生物有机肥替代化肥，追施有机硅水溶肥改良土壤等技术，平均每667 m² 可减少化学农药用量45.27%，减施化肥33.33%～38.89%，大白菜增产8.9% 以上。该模式已在河北省张家口坝上地区推广应用5 667 hm²（8.5 万亩）。     

几个籼粳交组合稻米品质性状遗传表达的鉴别

 用2个籼稻品种和3个粳稻品种配成籼粳交组合,研究了4个稻米品质（粒长、粒宽、糊化温度和直链淀粉含量）的遗传表达。粒长和粒宽遗传表达完全受二倍体母体基因型决定,而糊化温度和直链淀粉含量的遗传表达同时受二倍体母体基因型和三倍体胚乳基因型控制,胚乳基因型起主要作用。     

塑料大棚青花菜高产优质栽培技术

<正>冀中南地区3—4月气温较低,利用青花菜耐低温的特点开展塑料大棚栽培,一方面可以降低早春季节大棚蔬菜低温灾害风险,管理难度小,节省人工成本;另一方面可以优化种植结构,缓解土壤连作障碍,提高经济效益。塑料大棚是河北省中南部地区常见的蔬菜栽培设施,主要种植西瓜、番茄、黄瓜、菠菜、甘蓝、     

1961—2021年晋南苹果生长期气象灾害气候变化特征

利用1961—2021年晋南苹果主产区的逐日气温、降水量、日照时数等气象观测资料,分析了晋南苹果气象灾害的气候特征,主要分析了花期冻害、花期高温、膨大期高温和干旱、成熟期连阴雨以及冰雹的发生频次、极值的气候变化趋势。结果表明：1961—2021年晋南苹果花期冻害呈减轻趋势,极端最低气温在1996年出现突变,呈显著上升趋势;最近20年晋南苹果花期高温热害显著增多。膨大期高温热害呈加重趋势,近20年不仅高温日数明显增多,极端高温也出现多发态势;膨大期干旱趋势加重,2005—2018年是干旱最严重时期,连续无降水日数在1995年发生突变,之后为显著增多趋势。成熟期雨日增多、日照时数明显减少,连阴雨灾害发生趋势加重。近60年冰雹呈减少趋势,1994年开始冰雹灾害趋势减轻。近20年在气候变暖、干旱化背景下,晋南地区极端高温、强降水频发,苹果高温热害、干旱及秋季连阴雨灾害趋势加重;花期冻害和冰雹灾害趋势减轻。     

玉米抗粗缩病遗传及分子标记研究

Maize rough dwarf disease caused by Rice black-streaked dwarf virus (RBSDV) is transmitted by planthopper in China. Identification and development of resistant hybrids are complicated because of the inconsistencies in viral disease pressure every year. Marker-assisted selection can provide means for main-taining virus resistance alleles even in the absence of disease. In this paper a F₂ segregation population was constructed to identity the molecular markers linked to the resistance gene using a cross between a resistant and a susceptible parents (Qi319×Ye107). Fifteen-day-old seedlings of F₂ population were exposed to small brown planthoppers carrying RBSDV for 3 days in specific inoculation chamber. The inoculated plants were transplanted to screenhouse after removing the insects completely. In plant maturity stage the disease resistance of all the individuals were visually assessed. The results showed that 17, 8, 11, 51 and 122 plants were scaled from 0-4 respectively, in which 0 means no symptoms and 4 represents highly susceptible. Chi-square test demonstrated that the segregation ratio of phenotype was 1∶15 (resistant: susceptible) or 1∶6∶9 (resistant∶moderate∶susceptible) in the F₂ population, indicating RBSDV resistance of maize was controlled by two recessive genes. The F₂ individuals DNA were extracted and 261 SSR (simple sequence repeat) primers derived from maize genome ten chromosomes were selected from maize GDB database to construct genetic linkage map. The linkage map consisted of 71 polymorphic SSR markers, spanning a genetic distance of 996.6 cM with an average interval of 14.0 cM between adjacent markers. The resistant and susceptible gene pools were set up for BSA (bulked segregant analysis) and 6 polymorphism markers were obtained with BSA-SSR method between the two pools. The F₂individuals were further analyzed with 6 polymorphism markers. Chi-square test showed that phi 051, umc1407 and umc1432, mapped on chromosome 7 and 10, exhibited segregation distortion significantly and very significantly in susceptible individuals. These three SSR markers were identified as potential markers linked to the resistant loci.     

参与式在退耕还林中的应用比较研究

退耕还林是一项利国利民的系统工程,工程的实施既加快生态建设,又促进农民增收,与农民利益有直接关联。本文采用琵较研究的方法．以贵州省台江县朗等村和南兄村为例,在田野调查的基础上,分析了退耕还林工程实施考虑村民利益、鼓励农民参与的不同效果。认为在市场条件下农民变得越来越理性,退耕还林工程实施必须坚持以人为本,尊重农民的意愿,调动村民的积极性。