Sexual compatibility types of Bremia lactucae isolates originating from Lactuca serriola

Results are given on the occurrence of sexual compatibility types of seven isolates ofBremia lactucae originating fromLactuca serriola (prickly lettuce). It is concluded that the isolates studied are heterothallic. Both compatibility types (B1 en B2) were determined, but type B2 was prevalent. Sexual recombination ofB. lactucae isolates originating from wild and cultivated lettuce may occur.Samenvatting Zeven isolaten vanBremia lactucae, afkomstig vanLactuca serriola in Tsjechoslowakije, zijn onderzocht op hun sexuele compatibiliteitstype door ze te combineren met Nederlandse fysio's vanB. lactucae, afkomstig van cultuursla (L. sativa), waarvan het compatibiliteitstype (B1 of B2) bekend is. Alle isolaten vanL. serriola bleken heterothallisch te zijn, waarbij type B2 meer werd aangetroffen dan type B1. Sexuele recombinatie vanBremia-isolaten van wildeLactuca-soorten en cultuursla blijkt goed mogelijk te zijn.     

朝阳市主要经济林树种经济效益评价及发展预测

以朝阳地区主要经济林树种1958~2005年资料为基础,对山杏、大扁杏和大枣的经济效益进行科学评价。并采用数理统计方法,对3种主要经济林树种未来10年的发展前景进行了预测。     

我国蓝色粮仓科技创新的发展思路与实施途径

蓝色粮仓建设对保障食物安全、推动经济发展、催生新兴产业、彰显国家权益、改善生态环境以及突破产业瓶颈具有重要意义。在当前科技和产业背景下,如何卓有成效地构建蓝色粮仓已成为社会各界关注的热点。本文明确了蓝色粮仓的概念和特点,分析了蓝色粮仓构建的必要性和可行性,提出了实现渔业产业由大国向强国跨越以及提升科技创新和产业发展能力的总体目标,从聚焦重大需求、构建科技创新链,坚持原创驱动、突破重大科学问题,强化集成示范、支撑产业健康持续发展等方面论述了实施途径,即按照基础研究、重大共性关键技术、典型应用示范全链条布局的要求,坚持生态优先谋划,陆海统筹布局,针对种质创制、健康养殖、资源养护、友好捕捞、流通加工五大产业类型需求,实施良种引领、空间拓展、技术升级、产业示范四大行动,建立智慧养殖、智能捕捞、绿色加工三大体系,满足优质蛋白供给和产业转型升级两大需求,最终构建中国特色的蓝色粮仓。     

霍山石斛类原球茎诱导及其发育过程研究

 以霍山石斛试管苗带节茎段为材料, 诱导产生类原球茎, 并研究类原球茎发育过程。结果表 明, 霍山石斛类原球茎诱导的适宜培养基为Knudson + 2, 4-D 0.1 mg·L ^{- 1} + KT 0.05 mg·L ^{- 1} , 诱导率为25.50%。以固体静置、固液双层静置、液体静置、液体振荡4种不同培养方式进行增殖培养, 其中液体振荡培养方式更适于类原球茎快速增殖。类原球茎通过胚状体发生途径形成, 类似于合子胚的发育, 即经历原胚、心形胚、鱼雷形胚和子叶胚, 最后发育为成熟胚。类原球茎发育进程大致可分为类原球茎形成期、类原球茎肥大期、茎叶分化期、茎叶形成期以及茎叶伸长期等阶段。     

不同品种水稻产量形成过程的养分积累与分配特征研究

通过测定三系杂交稻"汕优63"、两系杂交稻"两优2186"和常规稻"IR64"不同器官N、P和K含量动态,探讨了3种水稻各生育期的养分积累与分配特征。结果表明:3种水稻稻株N含量均随生长过程逐渐下降,同一生育期水稻N含量以"汕优63"最高;除"汕优63"K含量在齐穗时明显上升外,3种水稻的K含量随生长过程逐渐下降;而P含量总体上在分蘖盛期最高。完熟期3种水稻的N积累量依次为24.79g/m2、15.14g/m2和14.42g/m2,P积累量为4.766g/m2、3.306g/m2和3.678g/m2,K积累量为2.439g/m22、.029g/m2和1.725g/m2。"汕优63"分配到籽粒中的N素比例为61.23%,分别比"两优2186"、"IR64"高17.97%和11.23%;分配到籽粒中的P素比例为62.97%,分别比"两优2186"、"IR64"高6.41%和9.63%;分配到籽粒中的K素比例为27.51%,分别比"两优2186"、"IR64"低3.00%和2.39%。在全生育期中,"汕优63"、"两优2186"和"IR64"的N需求量依次为31.33g/m2、22.88 g/m2、24.82g/m2,N、P、K吸收比依次为1∶0.192∶0.098、1∶0.219∶0.134和1∶0.255∶0.120。3种水稻中"汕优63"的养分生产效率最低。N、P、K生产效率"汕优63"依次为37.25kg/kg、193.80kg/kg和378.80kg/kg,"两优2186"依次为52.54 kg/kg、240.38kg/kg和392.16kg/kg,"IR64"依次为58.38kg/kg、228.83kg/kg和487.80kg/kg。三系杂交稻"汕优63"的N、P、K需求量大,积累量高,分配到籽粒中的比例亦高,与其高产特性相吻合。在保证N、P、K供给的前提下,进一步提高养分生产效率是实现"汕优63"高产、高效的关键。     

Desiccation and cracking behaviour of clay layer from slurry state under wetting-drying cycles

Laboratory tests were conducted to investigate the effect of wetting-drying (W-D) cycles on the initiation and evolution of cracks in clay layer. Four identical slurry specimens were prepared and subjected to five subsequent W-D cycles. The water evaporation, surface cracks evolution and structure evolution during the W-D cycles were monitored. The effect of W-D cycles on the geometric characteristics of crack patterns was analyzed by image processing. The results show that the desiccation and cracking behaviour was significantly affected by the applied W-D cycles: the measured cracking water content θ_c, surface crack ratio R_sc and final thickness h_f of the specimen increased significantly in the first three W-D cycles and then tended to reach equilibrium; the formed crack patterns after the second W-D cycle were more irregular than that after the first W-D cycle; the increase of surface cracks was accompanied by the decrease of pore volume shrinkage during drying. In addition, it was found that the applied W-D cycles resulted in significant rearrangement of specimen structure: the initially homogeneous and non-aggregated structure was converted to a clear aggregated-structure with obvious inter-aggregate pores after the second W-D cycle; the specimen volume generally increased with increasing cycles due to the aggregation and increased porosity. The image analysis results show that the geometric characteristics of crack pattern were significantly influenced by the W-D cycles, but this influence was reduced after the third cycle. This is consistent with the observations over the experiment, and indicates that the image processing can be used for quantitatively analyzing the W-D cycle dependence of clay desiccation cracking behaviour.     

酥梨产量构成因素的通径分析

两年定树调查测定44株次的酥梨产量及其相关的树高/冠径、花芽数、总果数、座果率、枝/果,叶面积系数、每果叶面积、平均单果重等8个性状。应用逐步回归法逐个别除对于产量没有显著线性效应的性状,得到包括总果数、每果叶面积和平均单果重在内的最优多元线性回归方程。再对入选的各个主要性状进行通径分析,明确其对产量构成的直接和间接效应。结果说明,提高酥梨单株产量。首先要具有一定的果量,其次是增加平均单果重,再次是维持叶面积与果实的适当比例。在树冠大小基本稳定的情形下,增加每果叶面积会造成果量减少而使产量下降,同时又可提高平均单果重而使产量上升。每果最佳叶面积应是提高平均单果重而使产量的上升量大于因果量减少而使产量的下降量,这样不仅可以增加产量,而且可提高果实的商品竞争力。     

影响黄瓜未授粉子房培养胚发生因素的研究

以不同基因型黄瓜为试材,研究了子房发育时期、热激处理时间、TDZ和AgNO3对黄瓜未授粉子房培养过程中胚发生的影响.结果表明处于开花前2～3 d的子房胚发生率相对较高,达83.8%;在子房培养开始阶段进行35 ℃处理的胚发生率显著高于对照(0 d),其中处理3 d 的效果最好;添加0.01～0.04 mg·L-1 TDZ的诱导培养基培养的胚发生率为20.0%～72.7%,其中添加0.04 mg·L-1 TDZ的胚发生效果较好;在诱导培养基中添加AgNO3可以提高胚发生率,同时能缩短胚出现的时间并提高胚产量.