水稻遥感估产系统研究——预试验和前期研究结果以及对开展估产研究的讨论

水稻遥感估产经过“六五”期间的预试验和“七五”期间的前期研究,对难度极大的我国南方水稻遥感估产取得了重要进展。初步明确了水稻遥感估产的研究途径、技术路线及研究方法,但要达到业务运行,还存在很多困难。因此,对今后进一步开展水稻遥感估产研究的几个重要问题加以讨论。     

园林计算机辅助设计实验课教学探讨

园林计算机辅助设计实验课是培养学生计算机辅助设计技能的重要课程,对实验课的重视、明确的实验课目标和任务及实验课教学中的控制方法运用是保证实验课教学效果的重要措施。     

内导叶滚筒式收鱼机设计与实验

针对深海域网箱养殖人工收鱼效率低、且劳动强度大,吸鱼泵等传统收鱼装置鱼损率高、需要装备大功率发电系统、不适合中小型收鱼船作业等问题设计了内导叶滚筒式收鱼机。对该装置的主体结构进行仿真,确定了主体结构发生最大等效应力和应力集中的位置,根据仿真结果进一步优化结构,并试制了实验装置。通过实验得出最优控制方案,即在倾角10°、转速15.3r/min情况下,有效输送量与功耗比最优,且滚筒在不同倾角下最优转速为15r/min,实验鱼损率为0.1%,满足用户要求。该装置能在保证一定收鱼效率的同时降低鱼损率,适合中小型渔船收鱼作业。     

正交设计研究山牡荆总黄酮提取工艺

[目的]建立山牡荆总黄酮的合理提取工艺,为山牡荆的开发及利用提供理论依据。[方法]以乙醇用量、乙醇浓度、提取时间和提取次数等为考察因素,以山牡荆总黄酮含量作为指标,应用正交试验对提取工艺进行优化。[结果]山牡荆中总黄酮的最佳提取工艺为乙醇用量12倍量、乙醇浓度70%乙醇、提取次数3次、每次1 h。[结论]该提取工艺简单、高效,适用于山牡荆的总黄酮提取。     

吉林省不同区域黑土供钾能力研究

选取吉林省4个不同区域的黑土,设置施钾肥和不施钾肥2种处理,通过连续种植黑麦草(耗竭试验)来观察黑土的供钾能力.结果表明:供试土壤中速效钾的动态变化特征各异,其"最低值"的大小和出现的茬数也不相同.速效钾最低值的变幅为33～40mg/kg,4号土壤速效钾含量降低的幅度最大,种植到第4茬时已经降低到原含量的8.96%,出现的茬数也较早.土壤中缓效钾下降幅度低于速效钾,"最低值"的变幅为527.87～824.28mg/kg,出现的茬数最早在第4茬,最晚在第7茬.从植物的吸钾动态特征来看,速效钾对首茬植物的总吸钾量贡献最大,其次是缓效钾,但随着种植茬数的增加,缓效钾和矿物钾的贡献率逐渐升高.试验中在计算黑麦草的吸钾量时,将缓效钾和矿物钾区分开,并分析了速效性钾、缓效钾及矿物钾对植物的有效性.     

陇中旱作区马铃薯品种筛选试验初报

为筛选出适宜陇中旱作区种植的优质马铃薯品种,解决当地马铃薯生产中存在的品种老化、抗病性弱、产量低、品质差等问题。以当地主栽马铃薯品种陇薯6号为对照,对引进的7个马铃薯品种进行了品种筛选试验。结果表明,宁薯19号、 陇薯11号折合产量较高,分别为39 245、37 350 kg/hm2,分别较对照品种陇薯6号增产15.87%、10.27%。综合分析认为,宁薯19号、陇薯11号较对照品种陇薯6号增产幅度大,综合农艺性状好,可在陇中旱作区及类似生态区种植。     

Long-term retention of coded wire tags in juvenile Arctic charr Salvelinus alpinus

Abstract  A hatchery experiment was organised to find out if the high loss rate of coded wire tags, noticed in connection with an Arctic charr Salvelinus alpinus (L.) restocking programme, was size-dependent and also to test head moulds for future taggings. Six moulds made by Northwest Marine Technology Inc. and five moulds made at the Finnish Game and Fisheries Research Institute were used. A total of 100 charr were tagged with standard-length coded wire tags using each mould. One-summer old charr at tagging were held for 534 days and two-summer old charr for 320 days. The tag loss rate varied between 0% and 54% and was negatively related to the size of the charr at tagging. The high loss rate was connected with the poor alignment of some moulds, such that a large proportion of the tags were located in the nasal cavity instead of the nasal cartilage. Testing of the moulds and careful grading of the fish for tagging is emphasised, especially if Arctic charr smaller than 20 g in weight are to be tagged.     

浙北地区利用冬闲虾塘饲养日本对虾的试验

利用饲养南美白对虾的冬闲虾塘 ,采取精养模式养一茬日本对虾 ,可提高围塘养殖的综合效益。本试验的放养密度为 2× 10 4余尾 / 6 6 7m2 ,单产 38.5kg/ 6 6 7m2 ,成活率 2 3.3%。盐度控制在 17以上     

Experimental evaluation of rainbow trout Oncorhynchus mykiss predation on longnose dace Rhinichthys cataractae

Laboratory and in‐stream enclosure experiments were used to determine whether rainbow trout Oncorhynchus mykiss influence survival of longnose dace Rhinichthys cataractae. In the laboratory, adult rainbow trout preyed on longnose dace in 42% of trials and juvenile rainbow trout did not prey on longnose dace during the first 6 h after rainbow trout introduction. Survival of longnose dace did not differ in the presence of adult rainbow trout previously exposed to active prey and those not previously exposed to active prey ( = 0.28, P = 0.60). In field enclosures, the number of longnose dace decreased at a faster rate in the presence of rainbow trout relative to controls within the first 72 h, but did not differ between moderate and high densities of rainbow trout (F_2,258.9 = 3.73, P = 0.03). Additionally, longnose dace were found in 7% of rainbow trout stomachs after 72 h in enclosures. Rainbow trout acclimated to the stream for longer periods had a greater initial influence on the number of longnose dace remaining in enclosures relative to those acclimated for shorter periods regardless of rainbow trout density treatment (F_4,148.5 = 2.50, P = 0.04). More research is needed to determine how predation rates will change in natural environments, under differing amounts of habitat and food resources and in the context of whole assemblages. However, if rainbow trout are introduced into the habitat of longnose dace, some predation on longnose dace is expected, even when rainbow trout have no previous experience with active prey.     

肉用仔鸡早期限食饲养试验

试验对7日龄肉用仔鸡进行了10d限食饲养,限食量分别为对照组的70%、60%、55%和50%,到56日龄时,除限食量为50%组日增重较低外,其它各试验组分别比对照组提高8.5%(P〈0.05)、7.5%(P<0.05)和6.79%,饲料报酬和心脏病发生率以限食量为60%和55%的试验组较好。试验就肉用仔鸡实施限制性饲养进行初探,旨在提供一个降低养鸡成本的途径。