内蒙古典型草原地上净初级生产力估测及模型模拟的研究

地上净初级生产力（ANPP）是陆地生态系统碳循环的重要组成部分，但由于估测ANPP的方法不同使得对ANPP的估测值存在很大的不确定性。本文采用3种方法（群落中所有种群当年最大地上生物量之和（ANPPC1）、当年群落最大地上生物量（ANPPC2）以及每年固定日期（8月30日）的地上生物量（ANPPC3））在种群、功能群和群落水平上分别对连续19年（1980～1998）的内蒙古羊草和大针茅草原生态系统功能（如ANPP、植物多样性和水分利用效率（WUE））的动态变化进行了比较分析，同时探讨了不同估测方法下气候和放牧对ANPP的影响，在此基础上利用DNDC模型进行了ANPP的模拟和敏感性分析研究，主要结果包括： 在羊草和大针茅草原群落中，不同主要植物种群或功能群多年平均地上最大生物量出现的时间不同，而同一植物种群或功能群的年地上最大生物量出现的时间存在年际间的变化。采用当年最大地上生物量和8月30日固定日期的地上生物量作为群落ANPP的这两种方法高估了建群种或禾草功能群在群落中的作用。 羊草草原群落多年平均ANPPC1、ANPPC2和 ANPPC3分别是257.5、190.1和166.0 g.m-2;相应的大针茅草原多年平均ANPPC1、ANPPC2和 ANPPC3分别是180.4、132.8和122.5 g.m-2。就群落生产力而言，后两种常用的方法二和方法三分别低估了草原群落ANPP 14.2%～40.0%和15.5～59.0%。本文研究表明尽管ANPPC1与ANPPC2和ANPPC3之间存在显著的差异，但二者之间存在极显著的相关性:羊草草原的ANPPC1= 59.587+1.061×ANPPC2（r2＝0.865, p＜0.001），ANPPC1= 92.329+1.017×ANPPC3（r2＝0.569, p＜0.001）;大针茅草原的ANPPC1= 32.918+1.114×ANPPC2（r2＝0.814, p＜0.001），ANPPC1= 76.120+0.875×ANPPC3（r2＝0.499, p＝0.001）。 种群、功能群和群落地上净初级生产力与气候因子间的关系因不同的估测方法而异。羊草草原的建群种羊草种群仅ANPPS3与8月和11月份的平均温度间存在显著相关性，而大针茅草原群落的建群种大针茅种群的ANPPS1和ANPPS2与3月份平均最高气温间呈负相关关系。在羊草草原群落，杂类草功能群ANPPF1和ANPPF2与3月份气温呈负相关关系;而灌木半灌木功能群ANPPF1和ANPPF2与3月份降水呈负相关关系。在大针茅草原群落，禾草功能群ANPPF1与5月份最高平均气温呈显著负相关关系。羊草草原群落ANPPC1和ANPPC3分别与11月份最低温度和平均温度存在显著负相关关系;大针茅草原群落ANPPC1与2和6月份月降水量间相关性显著，ANPP2与5月和11月份月平均最低温度呈显著负相关关系，而4～9月份，1和4月份平均最低温度对群落ANPPC3起决定作用。 在羊草和大针茅草原群落，由方法一得到的群落水分利用效率、Shannon植物多样性指数和均匀度指数与方法二或方法三得到的相应的指数间存在显著的差异，方法二和方法三得到的值间差异不显著。群落地上净初级生产力与相应估测方法的植物Shannon多样性指数和均匀度指数之间相关性不显著。 放牧条件下羊草或大针茅草原群落中的建群种羊草和大针茅在群落中的相对地上生物量较围栏内的相应植物种群的降低，而糙隐子草种群在群落中的比例上升。不同的放牧管理条件下，群落中植物种群地上现存量的季节动态发生变化。群落的植物组成及植物种群地上生物量在群落中总生物量的比例发生了明显的变化。利用遥感来估测地上净初级生产力时，分别低估了羊草和大针茅草原ANPP 52％和27％。 DNDC模型可以很好地模拟内蒙古典型草原生态系统的地上生物量，通过敏感性分析表明降水是草原植物生长的主要限制因子，在降水量增加或降低至日降水的30%时，模拟的地上生物量显著地高于或低于实测地上生物量值。在多年平均降水量为347mm的情况下，随着土壤粘粒含量的增加，地上生物量逐渐降低，与北美草原一致。

Nicotinamide in some seaweeds

The food value of marine algae lies mainly in their minerals and vitamins content (Chapman and Chapman, 1980). They are good source of vitamins like A,D,E,B series and C. Pakistan has a rich marine flora, so far more than 200 species of seaweeds have been reported (Shameel and Tanaka, 1992).

Faecal indicator organisms in frozen prawn products. Pt. 2. Survival of the organisms during freezing and frozen storage

The rate of survival of different types of faecal indicator organisms like Escherichia coli, enterococci etc. during freezing and frozen storage has been studied. Peeled and deveined prawns inoculated with a mixed culture of the above organisms were subjected to freezing and storage at -10̊F and examined for over four months.

Preliminary studies on blanching of prawn

The paper represents results on the studies undertaken to find out the causes of irregular drained weight conditions in commercial canned prawn samples. The tendency of cooked prawn to attain the equilibrium moisture content (72-74% in M. affinis and M. dobsoni) when in contact with brine has been found to be mainly responsible for the loss and gaine in drained weight. Underblanching results in loss of moistures from the meat during processing. It has been found that under standard blanching conditions, which is independent of initial moisture content, salt concentration of the blanch liquor and the temperature of sterilisation, the fluctuation in the drained weight could be avoided.

Length-weight relationship and condition factor of black carp (Mylopharyngodon spiceus Richardson) in Bangladesh

The length-weight relationship and condition factor of Mylopharyngodon spiceus were determined. The result of the study showed the dependence of weight (W) on the total length (L) in the following form: W= 0.006L(super 3.156) or in the logarithmic form Log W=- 2.1851 + 3.156 Log L. Standard errors of length and weight were 0.674 cm and 3.214 g respectively. The co-efficient correlation "r" was found to be 0.972 which indicated that the relationship between length and body weight of the fish was highly significant. The t-test also indicated that the correlation between length and weight was significant. The range and mean value of condition factor (K) were 0.865 to 1.041 and 0.958 respectively.

Optimization of stocking density for environmental-friendly improved extensive shrimp farming system in south-west part of Bangladesh

An experimental culture practice of P. monodon on extension approach was conducted in two brackish water earthen ponds of Demonstration Farm and Training Center (DFTC), Kaliganj, Satkhira. The experiment was aimed to provide farmers with appropriate technology that can immediately improve pond yield with keeping the environment in friendly condition. For optimization of stocking density of a cost effective environmental friendly improved extensive shrimp farming, the ponds were stocked with coastal river post larvae of P. monodon at the stocking rates of 2 pls/m² and 2.5 pls/m² without supplementary feeding. To control experimental error another five farmer's gher were used as replicates of each demo-pond. Considering the farmers buying ability, cost of inputs and other facilities kept minimal. The impact of stocking density was evaluated on the basis of growth, survival rate, production and economic return. Better production (average 299.01 kg/ha) with same survival rate (39.33%) were found with a stocking density of 2.5 pls/m² without causing any deterioration in the culture environment.

Protein from blanch liquor

A process is described for isolation of edible protein from blanch liquor, which is discarded as a waste at present from prawn canning factories. The protein isolated is colourless and odourless and contains an appreciable amount of salt from the brine used for blanching prawns. It is comparable to fish protein concentrate in amino acid composition.

高山植物唐古特红景天（Rhodiola algida Var.tangutica）抗冻蛋白的研究

抗冻蛋白（AFP）或热滞蛋白（THP）最早是从极区鱼和昆虫中发现的一类特殊蛋白质，其共同特性是能阻止体液内冰核的形成和生长，降低体液的冰点，使其冰点低于熔点（热滞效应）。近几年的研究表明，AFP在某些植物、细菌、真菌中也存在。生长在极端低温环境中的高山植物体内是否也存在AFP，据我们掌握的资料，还未见这方面的报道。为此，我们选择了青海高原海拔4000米高山生长的唐古特红景天为实验材料，并在这种植物中发现了抗冻蛋白。主要实验结果概括如下： 1. 唐古特红景天叶片有很强的抗冻性，可耐受-26.5 ℃的冰冻温胁迫。在北京地区夏季（7月）驯化20天后，半致死温度（LT_(50)）升高为-15.5 ℃。叶片质外体蛋白抽提液有明显的热滞效应（0.2 ℃），在AFP中存在糖基。SDS-PAGE分析表明，质外体AFP为分子量在43-85KD范围内的五条多肽。 2. 光镜组织化学切片显示，在红景天叶片中存在蛋白质量丰富的细胞;电镜细胞化学研究揭示，在细胞壁外层及细胞间隙中分布着明显的经钌红特异染色的糖蛋白，这种糖蛋白因环境温度升高而减少。结合前述的实验结果，确认这种细胞壁外层及细胞间隙中的糖蛋白，即抗冻蛋白。 3. 以唐古特红景天叶片为外植体，在MS+BA_2+NAA_(0.2)固体培养基上可诱导出黄绿色，松脆愈伤组织。愈伤组织细胞在同样成分的液体培养基中培养获得成功。在悬浮培养液中可检测到分泌蛋白的存在。经SDS-PAGE分析表明，经低温锻炼或ABA诱导后，细胞分泌蛋白的多肽谱带数增加。与此相对应的是，细胞的抗冻能力也明显提高。PAS染色揭示，多肽中均含有糖基。 4. 通过测定热滞值，确信细胞分泌蛋白是具有抗冻活性的糖蛋白。