黄瓜椰糠栽培营养液的适宜浓度探索

为了探索黄瓜椰糠栽培中适宜的流出液EC值指标,根据流出液EC值的高低来调节灌溉液浓度,实现肥料的合理施用。试验设置了1.8、2.2和2.6 mS·cm^-1三个流出液EC值指标,灌溉液浓度的“增减量(/g·L^-1)=(EC值设定值-EC值测定值)×流出率/%”。此模型不仅考虑了EC值设定值与测定值的差异,而且考虑了流出率因素。通过“配液浓度=在用浓度+增减量”,对灌溉液浓度进行连续调控。结果显示,伴随灌溉液浓度的升高与降低,流出液EC值围绕设定值上下波动,基本实现了稳定。流出液中氮、磷、钾、钙、镁元素的含量与EC值设定值正相关,反映了肥料供应水平的高低。当流出液EC值设定在2.2和2.6 mS·cm^-1时,黄瓜的产量差异不显著,却又都比EC值在1.8 mS·cm^-1设定值时显著增加。所以,2.2~2.6 mS·cm^-1可作为黄瓜椰糠栽培适宜的流出液EC值控制区间。     

不同投喂模式下新吉富罗非鱼的补偿生长

在23.7℃～31.2℃条件下,将初始体重约为31.65g的新吉富罗非鱼(NEW GIFT,Oreochromis niloticus)饲养在12只直径1.0m的圆形不锈钢桶中,每桶20尾,采用4种不同投喂模式饲喂47d:A组(每天投喂,对照组)、B组(隔天投喂)、C组(隔1d投喂3d)和D组(隔1d投喂5d),研究了不同投喂模式对新吉富罗非鱼补偿生长的影响。结果显示:D组的增重率显著高于其它各组(包括对照组)(P<0.05),达到164.76%;B、C、D组的摄食率和特定生长率显著高于对照组(P<0.05),B组和D组的饲料效率显著高于对照组(P<0.05),都达到70%以上。B组和C组新吉富罗非鱼仅有部分补偿生长能力,而D组显示了超补偿生长效应。这种补偿生长效应主要通过饥饿后食欲增强,摄食量增加实现,但饲料效率的提高对补偿生长也有一定的贡献。研究结果为罗非鱼的科学养殖及其补偿生长效应在生产中的应用具有一定的指导意义。     

饥饿和再投喂对白斑狗鱼体内RNA/DNA比值影响的研究

研究了饥饿和再投喂过程中自斑狗鱼肝脏和肌肉RNA/DNA比值的变化.随着饥饿时间的延长,白斑狗鱼体内RNA/DNA比值不断下降,体重逐渐减小,饥饿561时RNA/DNA比值下降幅度达到最大.恢复投喂后,白斑狗鱼摄食强度明显增大,生长加快,各组试验中肝脏和肌肉RNA/DNA比值均超过正常投喂水平.试验结果表明RNA/DNA比值与体重变化呈正相关,进一步证明RNA/DNA比值可作为衡量鱼类生长的重要指标之一.     

黄海北部沿岸水域营养水平及有机污染状况分析

主要根据１９９７的６月和８月对黄海北部沿岸对虾增殖放流调查,从营养水平和有机污染的角度,分析了黄海北部沿岸水域营养水平及有机污染状况。结果表明,营养盐含量具有明显的季节变化,并呈沿岸河口水域高于其他水域分布趋势。６月的营养盐含量水平接海水一类标准,富营养化程度和有机污染不明显,基本属正常水平。而８月的营养盐含量大部分测站均有不同程度地超过海水一,二类标准值,由计算的富营养化判断值,和有机污染指数,     

乳山湾东流区丰水期（8月）有机物及营养盐的环境容量

应用水质预测模型,分别采用海水一类水质标准和富营养化范围值的下限值作为相应要素的预测浓度,并根据１９９４年８月乳山湾东流区湾内外现场浓度,对其单位潮周期的化学耗氧量,无机氮和无机磷的环境容量进行了预测。根据预测结果,结合匡国瑞（１９８５）同期乳山湾东流区相应要素的环境容量的预测结果进行了比较分析。     

饥饿对凡纳滨对虾仔虾摄食行为和消化酶活力的影响

2004年5月,在中国海洋大学海水养殖教育部重点实验室内营造半精养、精养养殖模式,研究短期饥饿(0(对照组)、1、2、3、4、5、6d)对凡纳滨对虾仔虾摄食行为、摄食率及消化酶的影响。结果表明,两种模式中仔虾的摄食行为和摄食率都随饥饿天数的增加而呈现先上升后下降的趋势;半精养模式中,经饥饿再投喂后仔虾的胃蛋白酶、类胰蛋白酶和淀粉酶活力均随饥饿天数的增加呈现先上升后下降的趋势;精养模式中,胃蛋白酶活力也呈现以上趋势,但类胰蛋白酶和淀粉酶活力则在饥饿初期波动,然后下降。凡纳滨对虾仔虾遭遇饥饿胁迫后,通过提高摄食强度、摄食率及消化酶的分泌量来进行能量补充。但随着饥饿时间的延长,其应对饥饿胁迫的能力下降,各种消化酶活力呈降低趋势。实验表明,在半精养模式中,凡纳滨对虾对饥饿胁迫的承受能力高于精养模式。     

Soil Nutrients Balance in Sweet Orange Intercropped with Some Arable Crops

Sweet orange (Citrus sinensis (L) Osbeck Cv. Agege) was intercropped between 1996 and 1999 on an alfisol (Oxic Paleustalf), at the National Horticultural Research Institute, Ibadan Nigeria. The objectives were to determine the best compatible crops that would provide stable environmental conditions for sweet orange growth and yield. The companion crops were maize (M) (Zea mays L. DMR-LSR-W) in the early planting season, followed by cowpea (CP) (Vigna unguiculata L., Walp cv. Ife-brown) in the late planting season of each year, cassava (CA) (Manihot esculenta, Crantz cv. TMS30572), and pineapple (P) (Ananas comosus,cv. Smooth cayenne). For comparison, there were sole plots of sweet orange (SCT), maize (SM), cowpea (SCP), Cassava (SCA), and pineapple (SP) to serve as controls. The treatments were assigned to plots using a randomized complete block design (RCB). The growth of sweet orange intercropped with cassava was not as good as that of sole orange or orange intercropped with maize/cowpea (CT + M/CP) and pineapple (CT + P). Sweet orange in pure stands and CT + M/CP produced flowers 24 months after transplanting, with 75% and 87% of trees producing flowers and fruits, respectively. Forty-two months after transplanting sweet orange, SCT, CT + M/CP, and CT + CA had 1.63, 1.45, and 0.05 citrus fruit t/ha, respectively. Sweet orange intercropped with pineapple did not produce fruits. The effects of the crop mixtures on the soil showed that pH decreased by 2.17, which was a 5.2% decrease for all the cropping systems after three years of continuous cropping. There was a build up of nitrogen (N) and organic carbon in the soil for all the intercrops after the third year of the study. The cropping mixture of CT + M/CP and SCT had the highest N value of 0.70 g N/kg soil as compared to 0.30 g N/kg pre-planting. Zinc (Zn) a major nutrient of citrus, decreased from 3.16 mg/kg to 0.37 mg/kg under SCT and SP cropping systems. Sweet orange leaf analysis for N in all the treatments showed that leaf N was higher than the 2.5–2.7% optimum level, except for citrus intercropped with cassava, which had a leaf N concentration of 2.36%. Sweet orange intercropped with maize/cowpea had the highest phosphorus (P) level of 0.17%, followed by SCT, while sweet orange intercropped with cassava or pineapple had the lowest P values. Potassium (K) was in the adequate range in the sweet orange leaves for all the cropping systems, but the Zn content was below the satisfactory range of 20–50 ppm. The nutrient dynamics were results of the interaction among cropping systems, soil depth, and cropping cycle. Maize intercropped in the early planting season followed by cowpea in the late season was the most compatible crop with sweet orange in terms of fruit yield.     

不同坡位造林地酶活性与土壤养分的关系

研究了深圳市宝安区生态风景示范林的不同坡位———上坡和下坡造林地的酶活性与土壤养分关系。结果表明 :土壤养分含量和酶活性呈现下坡 >上坡的倾向。脲酶和过氧化氢酶与有机质和大多数土壤养分关系密切     

Isotope techniques to study phosphorus cycling in agricultural and forest soils: a review

A sound understanding of nutrient dynamics in ecosystems is required in order to manage these systems on a sustainable basis. A valuable approach to studying phosphorus (P) dynamics in soil-plant systems has been the use of P isotope techniques. Isotope techniques used for studying P cycling in agricultural and forest soils are reviewed in this paper with particular reference to advances made in the part 15 years. A brief discussion of the properties of P isotopes and their measurements is included together with techniques for measuring exchangeable P in the soil, dissolution and decomposition rates of inorganic and organic P sources applied to the soil, rates of organic P immobilization and mineralization, rates of P release and retention in the soil, root activity and lifter decomposition rates in forest soils, and gene probing and hybridization. Basic principles, assumptions, procedures, limitations and merits of methods are discussed. These techniques have served as or have the potential to be valuable tools for advancing our understanding of P dynamics in soil-plant systems, and for studying the molecular characteristics of microbial communities in relation to the cycling of nutrients in the soil.     

影响禾谷类作物籽实营养素含量的遗传因素分析

禾谷类作物是最重要的粮食作物,为人类提供了必需的营养物质,淀粉、脂肪、蛋白质、维生素和矿物质作为谷物的主要营养素,其含量是培育健康谷物的关键。为给育种研究中有效提升禾谷类籽实的营养品质及谷物的有效利用提供参考,并为培育更具全面营养的谷物提供理论依据,从饮食源头上为人类健康保驾护航。本文基于近年来相关文献资料的梳理归纳,对几种主要的禾谷类作物小麦、大麦、燕麦、水稻和玉米中的几种主要营养素含量进行比较分析,对影响这些营养物质含量和品质的遗传因素进行分析总结,认为小麦、大麦、燕麦、水稻、玉米等禾谷类籽实所含的各类营养物质有较大差异,不同物种遗传背景的差异是导致不同禾谷类籽实营养物质差异的根本原因,而在进化过程中基因突变的平行性又是导致禾谷类籽实中相同营养元素被同类基因编码调控的直接原因。