中国北方草原生物量年际动态

不同类型或同一类型不同区域的草地,其地上生物量在时间和空间上均存在差异,本文从不同的草地类型和时空尺度揭示植被生物量与环境因子间动态关系。结果显示,1)中国北方草原近30余年地上生物量总体呈下降趋势,水分条件较好的区域下降幅度较大,局部变化不显著,而近5年则呈持续增长趋势;2)时间序列上,年降水和年均温的交互作用对各区域草地地上生物量影响不显著;3)空间尺度上,温性草原年均温对地上生物量的影响较显著,高寒草原地上生物量的主要限制因子是降水。     

Preliminary study to evaluate the effects of dietary bile acids on growth performance and lipid metabolism of juvenile genetically improved farmed tilapia (Oreochromis niloticus) fed plant ingredient‐based diets

A 9‐week feeding experiment was conducted to investigate the effects of dietary bile acids (BAs) on juvenile genetically improved farmed tilapia (GIFT) (Oreochromis niloticus) based on the evaluations of growth performance and parameters relevant to lipid metabolism. Each of five vegetable protein‐based diets containing BAs at a level of 0, 0.05, 0.15, 0.45 or 1.35 g/kg diet was fed to three replicates with 40 fish (8.2 g per fish). The results showed that weight gain (WG) increased significantly with the increase in BAs from 0 to 0.15 g/kg diet and then decreased significantly at a higher BA supplementation. Dietary BAs significantly reduced the crude lipid content in the whole body, muscle and liver tissue of GIFT. Fish fed diet with 1.35 g BAs/kg diet developed serious nuclear migration and vacuolization in hepatocytes. Gall bladder appeared to contain white solid and has fragile capsules. Dietary BA supplementation had significant effects on serum biochemical indices and activities of lipid metabolism enzymes in liver and intestine. In conclusion, dietary bile acid supplementation (0.15 g/kg) can facilitate the lipid metabolism and therefore promote the growth of tilapia. However, overdosed dietary BAs induced gallstone development, disrupted lipid metabolism and depressed the growth performances of GIFT.     

不同寄主植物对异迟眼蕈蚊生长发育和繁殖的影响

异迟眼蕈蚊为害植物地下部分,造成韭菜、大葱、百合、蒜等作物的严重减产。研究异迟眼蕈蚊在不同寄主植物间的生长发育及繁殖规律,可为其预测预报及防治提供科学佐证。本研究在(25±1)℃、弱光照射(251.2lx)、相对湿度80%±5%的人工气候箱内,分别选用寄主植物韭菜、大葱、百合、蒜(蒜瓣和蒜茎),组建了异迟眼蕈蚊取食不同寄主植物的生命表,统计出了种群内禀增长率(rm)、净增殖率(R0)、平均世代周期(T)、种群加倍时间(t)和周限增长率(λ)等种群动态参数。结果表明,卵的发育历期在韭菜上最短(3.49d),在蒜瓣上最长(4.91d)。取食韭菜和大葱的幼虫发育历期最短,而取食百合的幼虫发育历期最长。蛹的发育历期在韭菜上最短(2.95d),在百合上最长(4.05d)。寄主植物对异迟眼蕈蚊卵的孵化率和蛹的存活率影响不显著,但显著影响幼虫的存活率。幼虫的存活率在韭菜上最高(76.7%),蒜瓣上最低(30%)。在韭菜、百合、大葱、蒜瓣和蒜茎上的单雌平均产卵量分别为91.98、52.14、85.48、73.91、72.96粒。异迟眼蕈蚊在韭菜上的种群净增殖率(R0)、内禀增长率(rm)和周限增长率(λ)最高,平均世代周期(T)、种群加倍时间(t)最短。异迟眼蕈蚊在韭菜上的适应度和嗜食性最好,繁殖速度最快。     

Effects of dietary fish oil replacements with three vegetable oils on growth,fatty acid composition,antioxidant capacity,serum parameters and expression of lipid metabolism related genes in juvenile Onychostoma macrolepis

Five isonitrogenous and isoenergetic diets with soybean oil (SO), linseed oil (LO), algae oil from Schizochytrium sp. (AO), mixed oil (MO, SO:LO:AO = 1:1:1) and fish oil (FO; control group) were selected to feed juvenile Onychostoma macrolepis (initial weight 1.86 ± 0.07 g) for eight weeks. The results showed that in the LO and FO groups fish grew best. There was no significant difference in specific growth rate (SGR) and feed efficiency (FE) between the MO and FO groups (p > .05). The highest contents of 18:2n‐6, 18:3n‐3 and 22:6n‐3 in liver and muscle were found with the SO, LO and AO groups, respectively (p < .05). There appeared the highest malondialdehyde (MDA) content and the lowest superoxide dismutase (SOD) activity in the fish liver of the AO group. There appeared the highest concentrations of serum glucose (GLU), cholesterol (CHOL) and triglycerides (TG) in the SO group. The expressions of lipid anabolism genes were significantly up‐regulated by dietary SO and LO (p < .05). The expressions of lipid catabolism genes were significantly higher with the AO, MO and FO groups (p < .05). This study recommended that LO or MO as a better vegetable oil source for juvenile O. macrolepis.     

川西北高原地区玉米育种现状及发展对策探讨

本文简述了川西北地区生态特点,概述了该地区玉米育种现状及存在的问题,在此基础上,结合高原玉米育种目标,提出了相应的发展对策。     

冬小麦抗旱性与膜脂过氧化的关系及其氮素调控机理

在大田试验条件下,测定了两个不同抗旱性小麦品种郑麦9023（水地品种,抗旱性差）和长武134（旱地品种,抗旱性强）在不同施氮量条件下拔节期叶片MDA、H2O2含量以及SOD、CAT活性的变化。结果表明,抗旱性和小麦叶片的保护酶活性和膜质伤害物质的含量密切相关,而且受氮素营养的调控。抗旱品种相对不抗旱品种具有较高的SOD和CAT活性,而MDA和H2O2较低;MDA和H2O2含量随施氮量的增加呈现先降后升的趋势,而SOD和CAT则呈相反的变化趋势。     

西北干旱半干旱区生态系统碳循环研究进展

干旱半干旱区是陆地生态系统的重要组成部分,在陆地生态系统碳循环过程中起着非常重要的作用,了解该区目前碳循环研究现状对准确评估陆地生态系统碳收支具有重要意义。概述了碳循环的基本概念,归纳了影响干旱半干旱区碳循环的环境因素（辐射,温度,水分条件等）,并总结了目前该区域碳通量研究现状。指出目前干旱半干旱区生态系统碳循环研究仍存在诸多薄弱环节,最后提出今后重点研究的方向：(1)不同时空尺度生态系统碳循环研究;(2)碳源/汇的物理、化学以及生物过程的研究;(3)从整体和系统的角度来研究干旱半干旱区生态系统碳循环;(4)制定统一的野外监测与试验方法。     

烤烟叶片含水量的光谱检测模型研究

为研究烤烟叶片中含水量随烘烤时间变化的问题,通过烘烤实验探索烤烟叶片含水量的可见-近红外光谱监测模型。针对光谱原始数据和预处理数据,利用交叉验证法采用偏最小二乘法建立回归模型,发现经过平滑处理的数据利用偏最小二乘法(PLS)可以较好地检测烤烟叶片含水量。基于全部波长建立回归模型,训练集r=0.9771,RMSEC=0.0742;交叉验证结果r=0.9573,RMSEC=0.1009;预测集r=0.9683,RMSEC=0.0862。结果表明,基于全部波长原始数据平滑处理的PLS模型预测烤烟叶片含水量是可行的。     

常熟虞山茶园土壤动物群落结构的多样性研究

为研究25~35年茶树种植区域土壤动物组成结构及多样性特征。对常熟市虞山林场茶园土壤环境进行了调查,共获得土壤动物样本1095个,隶属于4门7纲27类。优势类群为线虫、蜱螨目和弹尾目3类,占个体总数的88.18%,构成了该地区土壤动物群落组成的主体;常见类群为蜘蛛目、原尾目、膜翅目幼虫和鳞翅目幼虫4类;其他为稀有类群。三样地环境中土壤动物群落结构分析表明：个体密度依次为茶园2＞茶园1＞茶园3;类群数依次为茶园1＞茶园3＞茶园2;多样性指数(H’)依次为茶园3＞茶园1＞茶园2;均匀度指数(J)依次为茶园3＞茶园2＞茶园1;土壤动物优势度指数(C)依次为茶园1＞茶园2＞茶园3。茶园中三样地不同群落的相似性(q)分析表明：茶园1与茶园2、茶园1与茶园3、茶园2与茶园3的q值均在0.5＜q＜0.75之间,均表明相似水平为中等。茶园中土壤动物垂直分布特征表现为具有明显的表聚现象。     

齐口裂腹鱼维氏气单胞菌１６ＳｒＤＮＡ序列分析

报告齐口裂腹鱼病原菌的检测和生物学特性。从齐口裂腹鱼肠道中分离出菌株Spc0408, 采用常规形态特征的观察、生理生化试验、结合16SrDNA基因序列分析对其进行鉴定并构建系统发育树。该菌为革兰氏染色呈阴性,短杆形,无芽孢。生化鉴定结果显示具该菌有动力性,H2S、尿素阴性、不发酵木糖、鼠李糖、山梨醇等;β-半乳糖苷酶、葡磷胨水、枸橼酸盐阳性等。菌株16SrDNA的长度为1443 bp,登录号为JF929912,其和Genbank中多株维氏气单胞菌相似性高达97%,系统发育树显示菌株Spc0408和多株维氏气单胞菌聚为一簇。结合分离菌的表型特征及分子鉴定结果,可以判定该菌株在分类上属于维氏气单胞菌,本研究可以对相关病原菌的分类鉴定提供参考。