小麦根际pH,细菌数量,有机质变化研究

通过研究灰漠上和碱化灰漠上中小麦根际、非根际pH、细菌数量和有机质含量变化,发现两种土壤小麦根际上中细菌数量和有机质含量比非根际上中高。由于较低的pH值,因而灰漠土中小麦根际、非极际土中的有机质含量和细菌数量均高于碱化灰漠土中。     

植物分子农业研究中的问题与策略

植物分子农业是一个新兴的产业,人们对此很是关注。目前,植物分子农业的发展仍然有许多的限制因素。如蛋白产量低、下游加工困难、蛋白产品的异质性等等。研究人员正致力于对这些问题的研究,提出了许多技术方案。这些问题的解决,将使植物分子农业的发展进入一个新阶段。     

关于农科院校有机化学教学的探讨

针对农科院校有机化学课程的特点以及面临的问题,从教材选用、课题导入、教学过程、教学手段、学生练习以及教学评判等6个方面对有机化学教学进行了分析,将教学活动和学生的创造性思维有机地结合起来,以达到培养学生创新能力和综合素质的目的。     

渔船安全技术评价系统的开发与应用

为了辅助有关部门与管理人员收集指定区域的渔船的信息,并据此对渔船及其设备的安全技术状况进行科学、客观的评价,该文利用MS-ACCESS数据库的单机访问效率高、数据文件存储与合并灵活便捷的特点,开发了一种经济实用的渔船安全技术状况评价系统,实现了评价指标、标准与模型的自定义以及网络限制条件下的渔船安全技术状况评价数据采集与处理。该系统在应用过程中,数据由基层的渔业船舶检验工程师将有关渔船参数报到地方渔船管理部门,并最终上报到上级渔船管理部门,进行逐级收集、合并、上报与汇总,最后由相关部门的管理人员进行评价、统计与分析。该研究以某区域5700多艘24 m及以上钢质海洋渔船为样本,实施了渔船安全技术状况的评价。实用证明该系统用户环境配置安装简单,界面简洁方便,数据处理效率高,通用性强,运行维护成本低。通过渔船安全技术评价系统的开发与实施,可以对指定区域渔船的安全技术作出全面客观的评价,并辅助管理者对渔船技术状况和安全隐患进行科学分析,提出消除危险的最佳技术措施和方案,为主管机关制定相关政策、安全技术法规提供参考,进而大力改善区域渔船的安全生产状况。     

江永县植烟土壤有效锰含量分布及影响因素

采集了城关、松柏、桃川、允山、夏层铺5个植烟乡镇的104个土壤样品,研究了江永植烟土壤有效锰含量及其影响因素,为改良江永植烟土壤和烟区的可持续发展提供理论依据。研究结果表明：江永县植烟土壤有效锰含量适中,均值为19.56 mg/kg,变幅为3.80~93.80 mg/kg,变异系数达到93.30%,有效锰含量处于适宜范围的样本比例为49.04%。土壤有效态锰含量会随pH、有机质、全磷、全氮含量升高而降低。4个影响因素pH、有机质、全磷、全氮中,尤以有机质含量对土壤有效锰含量影响最大。     

基于ZigBee技术的群控虾池自动投饲装置设计与开发

设计一套虾池自动投饲装置,初步解决了虾池自动投饲问题。提出非接触定位、测距定位和接触定位三种投饲装置自动沿岸行驶方案,并对不同方案的优缺点进行了分析比较;对机械执行系统进行了详细的结构设计,该系统包含拉线和投饲装置两部分,拉线约束投饲装置自动沿岸行驶,投饲装置完成投料动作;采用应变式重量传感器和微控制器等,开发出投饲装置的控制系统,实现定时定量的投料控制。同时,采用新兴的ZigBee无线网络通信技术,实现对投饲装置的虾料重量和蓄电池电压的远程监控。投喂实验表明,该系统的工作过程稳定、可靠。     

Rainbow trout (Oncorhynchus mykiss,Walbaum ) develop a more robust body shape under organic rearing

Prolonged exposure to captive conditions has led to the development of a rainbow trout ‘farmed’ phenotype, which is different from that of wild trout. Selection for desirable productive traits in hatcheries has resulted in the development of some morphological traits that are maladaptive in nature. The recent development of organic aquaculture, guided by the well‐being of the fish, could potentially produce a new farmed phenotype that would be more adaptive in nature. In this study, rainbow trout reared in intensive and organic farms were compared by means of shape analysis, to detect patterns of shape variation associated with rearing environment. The results of this study highlight a significant effect of the rearing method on rainbow trout shape: organically reared trout showed a higher body profile, in particular in the head and trunk regions, shorter median fins and a deeper caudal peduncle. A combined effect of density and habitat complexity could have contributed to the observed shape differences: in organic rearing systems, lower densities and steady water could increase territoriality and aggressive interactions, promoting body designs more functional in rapid attacks and escapes.     

Supplementation effect(s) of organic acids and/or lipid to plant protein‐based diets on juvenile yellowtail,Seriola quinqueradiata Temminck et Schlegel 1845, growth and,nitrogen and phosphorus excretion

A feeding experiment was conducted to investigate the effect of organic acids and/or lipid supplementation on growth, utilization and environmental loading of nitrogen (N) and phosphorus (P) in juvenile yellowtail fed fishmeal (FM) and plant protein (PP) diets. Six diets as FM (FM‐based), FM+P (FM with inorganic P), FM+L (FM with lipid), PP+CA (PP with citric acid), PP+L+CA (PP with lipid and citric acid) and PP+L+FA (PP with formic acid) were formulated. Yellowtails were fed each of the diets in duplicate groups; once a day, 6 days a week to near satiation at water temperature 19.0–25.0 °C for 16 weeks. Fishmeal with inorganic P gave the best growth while PP+L+FA the lowest. However, growth increased in PP+CA and PP+L+CA. Addition of lipid significantly increased N and P retention resulting in significant reduction in N and P excretion. Citric acid and FA supplementation to PP diets also increased retention of P; hence, its excretion was lowered. Thus, CA, FA and lipid in juvenile yellowtail diets can help to partially replace FM with PP sources and reduce inorganic P use to minimize environmental loading from aquafeeds.     

Survival and growth of the sea cucumber Holothuria leucospilota Brandt: a comparison between suspended and bottom cultures in a subtropical fish farm during summer

The feasibility of co‐culturing the sea cucumber Holothuria leucospilota Brandt in a subtropical fish farm was investigated in a field study. Sea cucumbers were cultured in the fish farm in cages suspended at 4 m deep (suspended culture) and directly on the seafloor (bottom culture). The survival and growth of the sea cucumbers were monitored twice during the 3‐month, summer experimental period (May 26–August 14, 2010). Results showed that the suspension‐cultured sea cucumbers exhibited excellent survival rate (100%) during the whole study period. There also occurred no mortality in the bottom‐cultured sea cucumbers during the first culture period (May 26–July 13); but all these died from anoxia caused by water column stratification during the second culture period (July 14–August 14). The specific growth rate of the bottom‐cultured sea cucumbers (1.05 ± 0.21 % day^?1) was nearly double that of the suspended culture animals (0.57 ± 0.21 % day^?1) during the first culture period, and the growth rates of the suspended culture sea cucumbers in the second culture periods (0.46 ± 0.24 % day^?1) was only a little lower than that of the first period. The sea cucumbers H. leucospilota could ingest and assimilate sediment with high organic matter content with an average assimilation efficiency of 14.9 ± 3.9%. This study indicated that fish farm detritus can be effectively used as a food source for the sea cucumber and that it can be turned into a valuable secondary crop in the form of the sea cucumber biomass.     

Escaped farmed salmon, Salmo salar L., in the Glenarm River, Northern Ireland: genetic status of the wild population 7 years on

A previous study described genetic changes in a wild Atlantic salmon , Salmo salar L., population resulting from the spawning of escaped farmed salmon in the Glenarm River, Northern Ireland, in 1990. This study reports an extension of the original investigation with a further follow-up sample that was taken from the river in 1997 to assess the genetic status of the wild population two generations after the original hybridization between the wild population and the farmed strain. Overall genetic variation across eight polymorphic allozyme loci indicated that the wild population remains significantly different from the pre-escape population and from the immediate post-escape population, the presence of an allele not having been previously detected in this population ( GPI-1,2*140 ), suggesting that further incursion(s) of farmed salmon may have taken place.