丛生竹次生枝采萌圃促萌技术研究

采用截顶留母竹高度 (节数 )、秆基芽眼处理和施用不同浓度的生长调节物质 (含 6 -苄基嘌呤(BA) 萘乙酸 (NAA)的 MS培养液 )的三因素、三水平正交试验设计 ,分别对绿竹、孝顺竹和青皮竹 3个丛生竹种的次生枝采萌圃的促萌技术进行了研究 ,并对其中的绿竹次生枝采萌圃的持续经营技术进行探讨。研究结果表明 :(1)采用留母竹高度为 7节 ,损伤母竹秆基全部芽眼 ,并从 4月中旬开始 ,根据竹种配合施用 5次剂量均为 1L·丛 -1的 BA NAA不同质量浓度的 MS营养液 ,即绿竹每升含 2 mg BA 1mg NAA,孝顺竹每升含 10 mg BA 1mg NAA,青皮竹每升含 5mg BA 1mg NAA等技术措施 ,该 3个丛生竹次生枝采萌圃 ,每年每公顷可分别获得品质好的次生枝 14 250 0枝、114 0 0 0枝和 540 0 0枝 ;(2 )对上述的绿竹次生枝采萌圃按照竹丛内密度为 3株·丛 -1,丛内结构保持 1龄竹∶ 2龄竹为 2∶ 1,留母竹高度为 7节等技术措施进行改造 ,每年每公顷可获得次生枝 16 0 50 0枝 ,比每年重新营建采萌圃的方法增产 13%左右 ,并能数年持续经营     

非线性闭环汽车电动助力转向系统稳定性分析

建立基于魔术轮胎公式的驾驶员-装备EPS系统汽车闭环系统非线性操纵动力学模型,在此基础上运用现代非线性动力学理论对该模型在自治情况下进行非线性动力学特性分析和数值仿真,指出分岔速度对闭环系统非线性运动稳定性的影响规律,分析EPS系统参数对闭环系统Hopf分岔速度的影响,着重研究了EPS系统的电动机的转动惯量参数对闭环系统Hopf分岔速度的影响.     

Market‐led options to scale up legume seeds in developing countries: Experiences from the Tropical Legumes Project

There are several hurdles to ensure sustainable seed production and consistent flow of improved legume varieties in sub‐Saharan Africa (SSA) and South Asia (SA). The unreliable demand, autogamous nature of most of the grain legumes, and slow variety replacement rate by smallholder farmers do not provide strong incentive for private seed companies to invest in legume seed business. Unless a well thought‐out and comprehensive approach to legume seed delivery is developed, current seed shortages will continue, eroding emerging market opportunities. The experiences reported here are collated through a 10‐year partnership project, the Tropical Legumes in SSA and SA. It fostered innovative public–private partnerships in joint testing of innovative market‐led seed systems, skills and knowledge enhancement, de‐risking private sector initiatives that introduced in new approaches and previously overlooked entities in technology delivery. As new public and private seed companies, individual seed entrepreneurs and farmer organizations emerged, the existing ones enhanced their capacities. This resulted in significant rise in production, availability and accessibility of various seed grades of newly improved and farmer demanded legume varieties in the target countries.     

Indigenous soil and water conservation: A review of the state of knowledge and prospects for building on traditions

After half a century of failed soil and water conservation projects in tropical developing countries, technical specialists and policy makers are reconsidering their strategy. It is increasingly recognised that the land users have valuable environmental knowledge themselves. This review explores two hypotheses: first, that much can be learned from previously ignored indigenous soil and water conservation (ISWC) practices; second, that ISWC can often act as a suitable starting point for the development of technologies and programmes. However, information on ISWC is patchy and scattered. Many ancient, derelict systems are better described than traditions which still persist today. ISWC has been most commonly developed under dry and marginal conditions, and/or on steep hillsides. Sustained population pressure has often tended to stimulate ISWC. There is a need for more incorporation of ISWC into resource conservation programmes: many projects have ignored local traditions to their detriment. It is widely agreed that further study and research on ISWC is required and justified as a logical starting point towards developing adoptable and sustainable soil and water conservation systems for small-scale farmers.     

水稻胚乳组织的结构观察

【目的】阐明水稻糊粉层细胞、亚糊粉层细胞与中心胚乳贮藏细胞的结构特性。【方法】采用光镜、透射电镜与扫描电镜对水稻胚乳组织进行观察研究。【结果】糊粉层细胞分化过程中,大液泡变成小体积蛋白贮存液泡,蛋白贮存液泡又转变成糊粉粒。颖果背部比腹部有更多层糊粉层,但背部糊粉层细胞内糊粉粒的形成与积累速度却较慢。亚糊粉层细胞起初含有一些脂质体,后来脂质体消失,而其内部淀粉体与蛋白体逐渐增多。中心胚乳贮藏细胞含有淀粉体与蛋白体,蛋白体以液泡型蛋白体为主,它们可以相互融合而变大。中心胚乳贮藏细胞内的淀粉积累速度明显快于亚糊粉层细胞内的。成熟颖果的中心胚乳贮藏细胞内淀粉体最为密集,背部和侧部的亚糊粉层细胞内淀粉体排列较疏松,腹部的亚糊粉层细胞内淀粉体最为稀疏。【结论】水稻颖果背部与腹部的糊粉层细胞和亚糊粉层细胞的结构差异可能与养分吸收与转运有关;中心胚乳贮藏细胞内淀粉体发育速度快于亚糊粉层细胞。     

大黄鱼选育子二代生长性状研究

通过对选育和未选育2个群体大黄鱼（Larimichthys crocea）繁育得到的子代的卵径、油球径和口径进行测量,以及对其子代养殖过程中的生长性状进行测量比较,分析选育效果。结果显示,选育大黄鱼子代（XY-F2）和未经选育大黄鱼子代（HB-F1）平均卵径、平均油球径和平均口径之间差异不显著（P〉0.05）。拟合1~10月龄XY-F2和HB-F1的体长（x）、体质量（y）的生长曲线及体长（x）与体质量（y）的关系表明,两群体间体长（x）与体质量（y）的关系存在差异;XY-F2在体长（x）和体质量（y）的生长在后期高于HB-F1。分析其数量性状,选育子一代（XY-F1）2龄鱼体长、体质量现实遗传力分别为0.26、0.18,而XY-F2的体长、体质量现实遗传力分别为0.029、0.134。结果说明选育具有一定的作用,今后选育应该结合家系选择和家系内选择进行。     

立旋深松耕作对西北半干旱区土壤水分、肥力及马铃薯产量的影响

为探明立旋深松技术对西北半干旱区马铃薯生长、产量以及土壤理化性状的影响,于2018、2019年设置传统旋耕(T)、深翻(D)、立旋深松(V)3个处理,对马铃薯播前、花期和收获期土壤容重、萎蔫系数、田间持水量、碱解氮、速效磷、速效钾、有机质含量及马铃薯的产量进行了研究.结果表明:V处理比T、D处理马铃薯出苗率分别提高3....     

Development on the periphery: A case study of the sub‐national island jurisdiction of Pitcairn Island

This research reports on empirical findings of remote Pitcairn Island, the last remaining British Overseas Territory in the Pacific. It uses a qualitative methodology to discuss the island's potential for tourism development while recognising the issues and challenges faced by many small island developing states. However, as a sub‐national island jurisdiction Pitcairn presents a number of issues unique to its temporal socio‐political development and its centre periphery relationship with the metropole. The concept ‘decolonising without disengaging’ is posited to argue sub‐national island jurisdictions are places/spaces of innovative, creative and differentiated development processes that offer interesting departures from the conventional realms of sustainable discourse and island development. This concept is posited as a strategy of empowerment whereby autonomy without sovereignty does not necessarily hinder the development of tourism industries.     

F1代法检测棉铃虫种群对Bt棉的抗性等位基因频率变化

 在具有室内高抗Bt棉棉铃虫品系的前提下,F₁代法是检测棉铃虫对Bt棉抗性等位基因频率的最简捷、快速的生物测定方法。2010－2012年采用F₁代法检测了河北省邱县棉铃虫田间种群对Bt棉的抗性等位基因频率变化。结果表明,2010－2012年采集的122、141及124头田间雄虫中,分别有32、22及43头携带抗性基因,抗性等位基因频率分别为0.131(95%置信限CI:0.101～0.162)、0.078(95% CI:0.034～0.122)及0.199(95% CI:0.124～0.274)。2012年采用带毒饲料法测定河北邱县等4个地区Bt棉田间棉铃虫对Cry1Ac的抗性。结果表明,河北邱县棉铃虫种群的抗性最高(抗性倍数RR为19.2倍）,明显高于湖北荆州、湖北枣阳和安徽萧县种群的抗性（RR为4.9～9.3倍)。该地区长期大面积种植转单价Bt棉导致田间棉铃虫抗性进化,需要尽快采取有效的抗性治理措施。     

论农业高新区园中园发展模式

以科学理论为基础，农业高新技术为依托，从杨陵的产业实际出发，构建了杨陵农业高新区园中园滚动发展模式。该模式体现了农业高新区的空间区域性和产业发展的方向性，对全国农业高新区的技术、产业、经济发展具有理论和实践意义