广东山区开发的理论与实践：—广东山区开发理论与实践研讨会综述

本文述了“广东山区开发理论与实践研讨会”所达成共识的观点：广东山区开发具有重要的战略意义，广东山区开发必须走可持续肆展，农业产业化经营、工业化道路，同时必须搞好基础设施建设，组织好商品流通工作，优化资源配置。     

Stoffbildung, CO2-Gaswechsel, Kohlenhydrat- und Stickstoffgehalt von Winterweizen bei erhöhter CO2-Konzentration und Trocken-streß

Dry Matter Production, CO₂ Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO₂ Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO₂ concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO₂ concentration and of drought stress on dry matter production, CO₂ exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO₂ concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO₂ concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO₂ treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO₂ concentration showed a reduced response of net photosynthesis rate to increasing CO₂ concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.     

Mitigation of N2O emissions from grassland by nitrification inhibitor and Actilith F2 applied with fertilizer and cattle slurry

Abstract. Nitrous oxide (N₂O) is involved in both ozone destruction and global warming. In agricultural soils it is produced by nitrification and denitrification mainly after fertilization. Nitrification inhibitors have been proposed as one of the management tools for the reduction of the potential hazards of fertilizer-derived N₂O. Addition of nitrification inhibitors to fertilizers maintains soil N in ammonium form, thereby gaseous N losses by nitrification and denitrification are less likely to occur and there is increased N utilization by the sward. We present a study aimed to evaluate the effectiveness of the nitrification inhibitor dicyandiamide (DCD) and of the slurry additive Actilith F2 on N₂O emissions following application of calcium ammonium nitrate or cattle slurry to a mixed clover/ryegrass sward in the Basque Country. The results indicate that large differences in N₂O emission occur depending on fertilizer type and the presence or absence of a nitrification inhibitor. There is considerable scope for immediate reduction of emissions by applying DCD with calcium ammonium nitrate or cattle slurry. DCD, applied at 25 kg ha^–1, reduced the amount of N lost as N₂O by 60% and 42% when applied with cattle slurry and calcium ammonium nitrate, respectively. Actilith F2 did not reduce N₂O emissions and it produced a long lasting mineralization of previously immobilized added N.     

宿根花卉的特点及其在园林中的配置

根据宿根花卉种类繁多、色彩丰富、生长稳定、抗逆性强的特点,其在园林中的配置,宜于建花坛、花境,也可群植,与背景树相结合,还可作地被植物代替草坪,也可建单类花卉园.     

Long-term application of animal slurries to grassland alters soil cation balance

Abstract. Soil samples from a 32-year grassland field experiment were taken from 0–5, 5–10, and 10–15 cm soil depths in February 2002. Plots received annual treatments of unamended control, mineral fertilizer, three rates of pig slurry and three rates of cow slurry, each with six replicates. Samples were analysed for cation exchange capacity (CEC), exchangeable cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), pH and Olsen P. Exchangeable sodium percentage (ESP) was calculated as a sodicity indicator. Mean ESP was generally greater for slurry treatments than the control, with a trend of increasing ESP with application rate. This was particularly marked for cow slurry. At 0–5 cm depth ESP increased from 1.18 in the control to 1.75 at the highest rate of pig slurry and 5.60 at the highest rate of cow slurry. Similar trends were shown for CEC, exchangeable Na⁺, K⁺ and Mg²⁺, Ca²⁺ and Olsen P. The build-up of soil P due to slurry applications, together with this combination of physical and chemical factors, may increase the risk of P loss to surface waters, particularly from soils receiving high rates of cow slurry.     

Grouped, stacked rods and tapeta lucida in the retina of Japanese anchovy Engraulis japonicus

ABSTRACT: Morphology of the photoreceptor cells and tapetum of the Japanese anchovy Engraulis japonicus was studied by histologically and by chemical analysis. The Japanese anchovy has a duplex retina. The cones form parallel rows consisting of alternately placed long cones and bifid cones. Both types of cones are intimately associated and form triple units that are regularly spaced along the row of cones. The rods are grouped and stacked. This fish has a retinal tapetum lucidum composed of guanine and hypoxanthine. Three structures of the tapetum lucidum were recognized: platelet, diamond and rod types. Photomechanical changes include movements of the photoreceptor cells and the retinal tapetum. The retina of the Japanese anchovy is thought to be highly sensitive and well adapted to a dim light environment.     

Analysis of the Impact of Alfalfa Forage Production under Summer Water-Limiting Circumstances on Productivity, Agricultural and Growers Returns and Plant Stand

The trade-off between summer water conservation from alfalfa production and the effects on plant growth, agricultural crop value, and grower returns in the low desert area (Imperial, Palo Verde, Parker and Yuma Valleys of California and Arizona) was analysed using an experimental plot in the Palo Verde Valley. The purpose was to provide a basis for evaluating water conservation decisions and policies. Four summer dry-down periods (withdrawing water for a predetermined period) of 0 days (control), 35 days, 70 days, and 105 days were analysed. Our results show that whereas the various dry-down periods would provide water conservation ranging from 254 to 944 million m³, the region would experience agricultural income decline by US $16 to US $73 million. For growers, benefits of dry-down would be effective only if the water price exceeds US $0.045 m⁻³ in California and US $0.036 m⁻³ in Arizona. Also dry-down would have possible adverse effects in the following areas including declines in plant stand density, long-term productivity, service industry sales, employment and biological benefits of soil fertility and organic matter that is attributed by the alfalfa plant in which case agriculture's and growers monetary losses could increase.     

杉木林杆材阶段能量积累和分配的研究

目前森林生态系统生产力的研究 ,多以干物质量作为指标 ,这对深入了解生态系统的功能 ,生态效益都有一定的局限性。必须把生物量与能量结合起来 ,因为生物量和能流的研究 ,是人工林生态系统结构和功能的研究中最主要的一环 ,是研究物质生产、物质循环和能量流动的基础。关于森林各组织器官的热值和能量的研究 ,国内外许多学者做过这方面的工作。刘世荣等 (1990 )研究了落叶松 (Larixgmelinii)林群落能量积累、分配、固定和转化的规律 ;陶金川等 (1990 )探讨了银鹊树 (Tapisciasinensis)群落的生物量和能量的现存量 ;张文其等 (1995 )对鹤山…     

Dynamics of the Cumulation of Macroelements – Phosphorus, Potassium, Calcium and Magnesium During Development to Maturity of Soybean Seed

Dynamics of the cumulation of phosphorus, potassium, calcium and magnesium in developing seed of four soybean genotypes under the defined climatic conditions in the course of three years was observed. Samples were being taken at weekly intervals from the point at which the grain reached a size suitable to be analyzed up to the full maturity of the seed. By analyzing the results it was found out that the intense cumulation of the minerals tested took place during the stages III and IV of the seed development, that is, in the course of intense cumulation of dry matter and the most expressive metabolic activity in the seed. Investigation of the impact of climatic conditions provides evidence that cumulation of the tested macroelements has been favourably influenced by increased precipitation along with moderate air temperatures within the seed developing period. The highest content of the minerals found with the cultivar Maksimirka independently of the year investigated reveals that mineral cumulation in soybean seed is affected by the cultivar and genetic particularity.     

西瓜蔓枯病研究 Ⅰ.症状及病原

本文详细报道了西瓜蔓枯病的症状和病原菌的形态特点,并鉴定其有性阶段为Mycosphaerellamelonis(Pass)Chiu et Walker,无性阶段为Ascochyta-cucumis Fautr et Roum.此外,还在其他瓜类作物上作了病原菌的致病性试验.