陕西烟草蚜传病毒病防治技术研究

在烟草炼苗期采用杀蚜剂、病毒抑制剂、纱网罩烟苗 ,田间生长期采用杀蚜剂、病毒抑制剂和不同移栽期防治烟草蚜传病毒病。结果表明 ,杀蚜剂防治烟草蚜传病毒病效果较差 ,病毒抑制剂效果一般为 6 0 %左右 ;随移栽期推迟 ,烟草蚜传病毒病发病显著减轻。炼苗期烟草苗床是传毒介体有翅蚜着落的靶子中心 ,是烟田蚜传病毒病的主要初侵染源 ,为防治烟草蚜传病毒病的关键时期。用纱网罩烟苗能阻止传毒介体与烟草接触交叉传染 ,结合适时喷施病毒抑制剂 ,能有效防治烟草蚜传病毒病发生 ,同时能有效保护环境和介体天敌     

玉米自交系耐旱性的模糊隶属函数法分析

以与玉米自交系幼苗质膜损伤程度有关的过氧化物酶、超氧化物歧化酶、过氧化氢酶、丙二醛、维生素C和电导率为指标,用模糊隶属函数法对玉米自交系的耐旱性进行综合分析。结果表明,模糊隶属函数法可以避免单一指标的片面性,能较全面地评价玉米的耐旱性。     

追氮时期对冬小麦籽粒品质和产量的影响

采用水泥池栽和大田栽培两种种植方式 ,研究了追氮时期对冬小麦品质和产量的影响。结果表明 ,与起身期施氮肥相比较 ,拔节期和挑旗期追施氮肥 ,促进了籽粒各蛋白质组分和蛋白质总量的提高 ,增加了谷蛋白大聚合体的含量 ;提高了籽粒容重、出粉率和面粉的湿面筋含量及沉淀值 ;延长了面团稳定时间 ,同时籽粒产量亦显著增加     

古惠州西湖风景园林形成阶段与特征考实

惠州西湖是古代岭南具有代表性的风景名胜区,现遗存的山水景观有待进一步恢复。基于文献史料收集、实地勘察,结合历史图像,对惠州西湖风景园林的形成进行了考证与探析：从水域状态、建筑营造、景观完整度、功能种类以及城湖关系几方面进行分析、对比,提出惠州西湖的形成分为汉、晋、唐、宋、明代几个主要的发展阶段,并具有相应的风景园林特色,其风貌的形成是长期动态的过程,并非静止不变     

毛乌素沙地飞播植被演替的阶段与速度

毛乌素沙地飞播植物的演替，可分为３个时期或阶段。第１阶段为飞播植物群落阶段；第２阶段为飞播植物＋天然植物或飞播植物＋油蒿群落阶段；第３阶段为天然植物群落阶段或油蒿群落阶段。从各阶段所能维持的时间或演替的速度来看，毛乌素流动沙地飞播以后，飞播植物占优势的阶段最大不超过２０年，飞播植物群落阶段和飞播植物与油蒿共同占优势的时间最大不超过３５年。也就是说，３５年以后，天然植物油蒿在群落中占绝对优势，而飞播植物仅作为伴生种存在。     

A longitudinal study on the acceptance and effects of a therapeutic renal food in pet dogs with IRIS‐Stage 1 chronic kidney disease

Currently, nutritional management is recommended when serum creatinine (Cr) exceeds 1.4 mg/dl in dogs with IRIS‐Stage 2 chronic kidney disease (CKD) to slow progressive loss of kidney function, reduce clinical and biochemical consequences of CKD, and maintain adequate nutrition. It is unknown if dietary interventions benefit non‐azotemic dogs at earlier stages. A prospective 12‐month feeding trial was performed in client‐owned dogs with IRIS‐Stage 1 CKD (n = 36; 20 had persistently dilute urine with urine specific gravity (USG) <1.020 without identifiable non‐renal cause; six had persistent proteinuria of renal origin with urine protein creatinine (UPC) ratio >0.5; 10 had both). Ease of transition to therapeutic renal food and effects on renal biomarkers and quality of life attributes were assessed. Dogs were transitioned over 1 week from grocery‐branded foods to renal food. At 0, 3, 6, 9, and 12‐months a questionnaire to assess owner's perception of their pet's acceptance of renal food and quality of life was completed. Renal biomarkers, including serum Cr, blood urea nitrogen (BUN), and symmetric dimethylarginine (SDMA), and USG and UPC ratio were measured. Of 36 dogs initially enrolled, 35 (97%) dogs were transitioned to therapeutic renal food. Dogs moderately or extremely liked the food 88% of the time, ate most or all of the food 84% of the time, and were moderately or extremely enthusiastic while eating 76% of the time. All renal biomarkers (Cr, BUN, and SDMA) were decreased (p ≤ .05) from baseline at 3‐months, and remained decreased from baseline at 12‐months in dogs completing the study (n = 20). Proteinuria was reduced in 12 of 16 dogs (p = .045) with proteinuria. Owners reported improvement in overall health and quality of life attributes, and hair and coat quality (all p < .01). In summary, dogs with IRIS‐Stage 1 CKD readily transition to renal food. Decreasing serum biomarker concentrations and reduction in proteinuria suggest stabilized kidney function.     

短叶十三号萝卜当年采种技术初探

本试验根据阶段发育的理论,探讨了影响短叶十三号萝卜当年采种的技术因素以及相互关系,结果表明:在种子萌动时低温处理15天,播种期选择于7月初,在露地条件下,一年繁殖两代原种是有可能的。     

Interactions between plant life span, seed dispersal capacity and fecundity determine metapopulation viability in a dynamic landscape

Classical metapopulation models do not account for temporal changes in the suitability of habitat patches. In reality, however, the carrying capacity of most habitat types is not constant in time due to natural succession processes. In this study, we modeled plant metapopulation persistence in a successional landscape with disappearing and emerging habitat patches, based on a realistic dune slack landscape at the Belgian–French coast. We focused on the effects of the variation of different plant traits on metapopulation persistence in this changing landscape. Therefore, we used a stage based stochastic metapopulation model implemented in RAMAS/Metapop, simulating a large variation in plant traits but keeping landscape characteristics such as patch turnover rate and patch lifespan constant. The results confirm the conclusions of earlier modeling work that seed dispersal distance and seed emigration rate both have an important effect on metapopulation persistence. We also found that high population growth rate or high recruitment considerably decreased the extinction risk of the metapopulation. Additionally, a long plant life span had a strong positive effect on metapopulation persistence, irrespective of the plant's dispersal capacity and population growth rate. Plant species that invest in life span require less investment in offspring and dispersal capacity to avoid extinction, even in dynamic landscapes with deterministic changes in habitat quality. Moreover, metapopulations of long-lived plant species were found to be much less sensitive to high levels of environmental stochasticity than short-lived species.     

银杏吸收根营养元素吸收及分配规律的能谱分析

 能谱分析银杏吸收根组织对营养元素的吸收规律，结果表明：1．根对营养元素的吸收有两次高峰，第一次出现在营养液培养处理后的4～6 h左右，第二次出现在10-24 h左右；2．营养元素的吸收规律和在银杏根不同组织分布与培养液中元素种类、离子的类型和银杏根系对营养元素需求特性有关;3．银杏根系中K、Na元素积累量较高，显示银杏是一种代谢强度大、耐盐的植物。     

家蚕新品种夏芳和秋白原蚕5龄给桑量的研究

本实验用家蚕夏秋用新品种夏芳、秋白原种,给予4种不同的5龄给桑处理,调查其幼虫、茧、卵的各项成绩.结果表明,两品种均以克蚁5龄给桑量59kg(克蚁全龄用桑69Kg)的各项指标最佳,说明适量给桑的各项成绩均比偏多或偏少给桑的效果优良.