辽宁省盘锦沿海地区田菁的栽培及其改良盐土的效果

辽宁省滨海盐渍土多分布于低洼易涝地区,以盘锦沿海地区为主.这些盐碱地,除部分已开垦种植外,尚有大面积荒地.已被垦殖的土地,也因盐碱重,肥力低,危害作物出苗和生长,引起作物减产,甚至成片死亡,严重地影响单位面积产量和总产量.为了加速盐碱地的改造利用,使达到稳产高产,种植绿肥作物是有效措施之一;特别是在水旱轮作中,绿肥占着重要的地位.因此研究绿肥作物的栽培和提高土壤肥力的作用,对农业生产的发展具有重大的实践意义.本文系根据1957年到1964年的部分研究资料加以整理,供各地参考.     

黑土和白浆土上磷肥肥效与土壤性质和氮素供应水平的关系

一般认为磷肥施入土壤后,能迅速地转化成难以被作物利用的状态.武玫玲等人^[1]指出,可溶性磷酸盐施入土壤2小时后,有40%转化为0.5N HAc不能溶解的状态,经过一个月增加到80%以上.许多研究亦指出,土壤可溶性和交换性盐基的性质和含量^[2]、土壤粘土矿物组成^[3]、土壤的pH值^[4]、影响化学平衡的时间、温度和水分舍量等^[5],都可影响磷肥的转化过程.陈魁卿等^[6]认为,黑土中的活性铁铝合量与磷酸的吸收没有规律性;而白浆土<0.01毫米的物理性粘粒与磷肥吸收关系较大.综上可见,磷肥肥效受到土壤诸因子的制约.     

DNA polymorphism in the growth hormone gene and its association with weight in olive flounder Paralichthys olivaceus

ABSTRACT: Variation within the growth hormone gene and its association with growth trait in the olive flounder ( Paralichthys olivaceus ) was investigated. Based on Southern blot analysis and using various kinds of restriction endonucleases, it was demonstrated that the growth hormone gene exists as a single copy gene in the olive flounder. Polymorphisms of various lengths were also detected by Southern blot analysis, and by the subsequent digestion of the polymerase chain reaction (PCR) -amplified growth hormone gene fragment with Sau 3AI restriction enzyme. To study the possible association between variation in the growth hormone and weight, 60 progenies of the hatchery strain of three various sizes (large, medium and small weight) were selected and the entire genetic structure of the growth hormone gene was analysed. A total of 15 different genotypes was observed from the random association of six haplotypes. Significant heterogeneity of the growth hormone gene with haplotype and genotype frequencies was detected among the different-sized groups.     

Evidence of density-dependent effects on population variation of Japanese sardine (Sardinops melanosticta) off Korea

Interannual variation of some biological parameters for the Japanese sardine, Sardinops melanosticta, population in Korean waters was investigated using scientific surveys and fisheries information since the late 1970s. The abundance and geographical coverage of sardine eggs were high (peak in 1986) and broad when spawning biomasses were high in the mid 1980s, and vice versa in the late 1970s and the early 1990s. Also, feeding and spawning areas based on fisheries information exhibited the same pattern of expansion/contraction as seen in ichthyoplankton surveys. Annual Gonadal Somatic Index (GSI) in spawning season (February to April) and the size at age 1 of sardine were reduced during the high abundance period. It is suggested that density‐dependent effects on the reproduction and growth of the sardine population in Korean waters existed.     

Effect of dietary protein and lipid levels on growth and body composition of juvenile turbot (Scophthalmus maximus L) reared under optimum salinity and temperature conditions

Effect of dietary protein and lipid levels on growth and body composition of juvenile turbot was determined at optimum salinity and temperature conditions of 17 g L^?1 and 19.2 °C, respectively, by using 3 × 2 (protein levels: 550, 600 and 650 g kg^?1; lipid levels: 69 and 168 g kg^?1) factorial design with three replications of each. Fish were hand‐fed to satiety twice daily throughout the feeding trial. Weight gain and specific growth rate of fish were significantly (P < 0.05) increased with increased dietary lipid level, but not by dietary protein level. Daily feed intake was significantly (P < 0.05) affected by both dietary protein and lipid levels. Feed efficiency ratio and protein efficiency ratio were significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Moisture content of whole body was significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Crude lipid content of whole body was significantly (P < 0.05) affected by dietary lipid level, but not by dietary protein level. Significantly higher 20:5n?3, 22:6n?3 and n?3 highly unsaturated fatty acids were observed in turbot fed the low lipid diet than fish fed the high lipid diet in all protein levels, but significantly lower 18:2n?6 was observed in fish fed the former compared with the latter. In considering results of growth, specific growth rate and efficiency of feed, optimum dietary protein and lipid levels for juvenile turbot seemed to be 550 and 168 g kg^?1 of the diet, respectively, under optimum salinity and temperature conditions.     

Effects of dietary protein and lipid level on growth and body composition of juvenile ayu (Plecoglossus altivelis) reared in seawater

A 3 (protein levels, 380, 460 and 520 g kg^–1 diet) × 2 (lipid levels, 65 and 140 g kg^–1 diet) factorial experiment with three replicates was conducted. Weight gain, feed efficiency and daily feed intake were not significantly affected by dietary protein level, but were by dietary lipid level. Weight gains of fish fed 65 g lipid kg^–1 diet were significantly, or slightly, higher than for 140 g lipid kg^–1 diet at all protein levels. Daily protein intake was significantly affected by both dietary protein and lipid levels ( P  < 0.002). Daily lipid intake was not significantly affected by dietary protein level, but was by dietary lipid level ( P  < 0.001). Protein efficiency ratio was significantly affected by dietary protein level ( P  < 0.02), but not by dietary lipid level. Protein efficiency ratio tended to improve with the decrease of dietary protein level at the same lipid level. Moisture, protein and lipid contents of whole fish were significantly affected by dietary lipid level ( P  < 0.01). Increased dietary lipid did not improve growth or feed efficiency, but increased body fat deposition. It was concluded that the optimum dietary protein and lipid level for growth of juvenile ayu may be 380 and 65 g kg^–1 diet, respectively, when fish were fed to satiety three times daily in seawater.     

Histological observations of seasonal reproductive and lunar-related spawning cycles in the female honeycomb grouper Epinephelus merra in Okinawan waters

Seasonal reproductive and lunar-related spawning cycles of the female honeycomb grouper Epinephelus merra inhabiting Okinawan waters were examined by histological observation of ovaries. Gonadosomatic index (GSI) increased beginning in May and peaked in June. Histological observations revealed that many oocytes laden with yolk were present in the ovaries from May to August. From September to October, ovaries were occupied by immature oocytes. These results suggest that the reproductive season of E.   merra lasts for 4 months from May through August in Okinawan waters. When the fish were collected according to the lunar cycle, GSI increased with the approach of the full moon. Oocytes at various development stages were observed from the first quarter to the full moon. Fresh ovulatory follicles were present in the ovaries around the last quarter moon. These results suggest that E.   merra has a lunar spawning cycle and spawns between the full moon and the last quarter moon. Ovarian features of the fish collected around the last quarter moon were different among individuals; some fish had many oocytes at the tertiary yolk stage in the ovaries, while the ovaries of the others were occupied by the oocytes at the peri-nucleolus and the oil droplet stages. This observation suggests that a minor release of eggs occurs in this species before or after a major spawning lunar day. Oocytes at the migratory nucleus and the maturation stages were not observed in any ovarian samples. This may mean that maturation of oocytes is related to the spawning behavior of this species and makes rapid progress in the process of aggregation at the spawning sites.     

The role of the lethal extracellular cytolysin of Aeromonas salmonicida in the pathology of furunculosis

Abstract. The histopathological effects of intramuscular (i.m.) and intraperitoneal injections of the purified lethal cytolytic toxin of A. salmonicida in Atlantic salmon, Salmo salar L., were restricted to extensive degranulation of eosinophilic granular cells (EGCs) in the gills (both routes) and a limited coagulative necrosis of muscle fibres at the site of i.m. injection. The severity of these lesions did not apparently differ amongst fish that were moribund within 48 h and the surviving fish at 90 h. Previous studies indicate a maximum time to death caused by this toxin of 48 h. Thus, it is difficult to account for death of the fish from the toxin solely on the grounds of the histopathological features. It is suggested that a complex metabolic dysfunction results in death. The mechanism of 'furuncle' formation was demonstrated to result from a combined effect of the cytolysin and the purified 70-kDa protease present in the ECP. When i.m.-injected singly, the purified cytolysin produced a limited coagulative necrosis and the purified protease produced a limited liquefaction and haemorrhaging. In combination, they induced the extensive liquefactive haemorrhagic 'furuncle' characteristic of the whole ECP.     

Use of effluent water from fish-ponds as a food source for the Pacific oyster, Crassostrea gigas Thunberg

Abstract. Growth rates, condition indices and diet composition of the Japanese oyster, Crassostrea gigas Thunberg, were studied in two types of ponds which form part of a fish-bivalve integrated culture system. Although abiotic parameters (e.g. temperature, salinity, pH, ammonia, particulate inorganic matter) were similar in the two pond types, oysters supplied with water from a sedimentation pond grew significantly faster and showed better condition indices than the oysters supplied with water from the PVC-lined ponds. It is suggested that the main reasons for the better performance of the oysters supplied with water from sedimentation pond water are: higher algal diversity, additional nutritious Food consisting of attached benthic diatoms and stable algal concentration.     

Laboratory culture and estimated life span of the Eastern Atlantic squid, Loligo forbesi Steenstrup, 1856 (Mollusca: Cephalopoda)

Abstract. First culture results are presented from four major experiments (lasting up to 478 days) on the commercially important squid species, Loligo forbesi Steenstrup, Details are provided on eggs, hatching, feeding, growth, survival, behaviour and sexual maturation. Best survival during the critical first 75 days was 15%. The hatchlings (up to 4.9mm mantle length, ML) are the largest among the genus Loligo , and the largest squid grown was a male 155mm ML and 124g. First schooling was observed only 40–50 days post-hatching. Spawning was not achieved although males reached maturity, females had maturing ova and mating was observed. The largest giant axon measured was 425μm in diameter (from a female 130mm ML), a size suitable for most biomedical applications. Laboratory data suggest a 2-year life cycle compared to fishery data which suggest a 1-year cycle.