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81.
Arthropod predators are abundant in turfgrass systems, and they play an important role in managing pests. Understanding the vertical distribution of predation is critical to developing cultural strategies that enhance and conserve predatory services. However, little is known on how the predation is vertically distributed within the turfgrass canopy. Thus, the objective of this study was to determine the vertical distribution of predation within the turfgrass canopy. Clay models were used to emulate the general appearance of Noctuidae caterpillars, to estimate the predatory activity. The choice and no-choice experiments were conducted by placing clay models at 2.54, 5.08, and 7.62 cm from the thatch surface and denoted as lower, intermediate, and upper levels, respectively, within turfgrass canopy. The predator-mediated impressions, paired mark, scratch, deep cut mark, deep distortion, prick, dent, stacked surface impression, scooped mark, granulation, and U-shaped mark, were identified on clay models. The incidence and severity of impressions were significantly greater on clay models placed at the lower canopy level than on those placed at the intermediate and upper canopy levels in the choice and no-choice experiments (P < 0.05). Thus, predators are more likely to find their prey at the soil level. This information can be used to refine management strategies, such as mowing height and insecticide use for effectively managing soil-borne and foliar-feeding arthropod pests and beneficial arthropods.  相似文献   
82.
玉米Rf3基因近等基因系(NIL)的构建及RAPD验证   总被引:6,自引:0,他引:6  
利用杂交、回交和自交序成了玉米CMS-S型育性恢复基因Rf3的一对近等基因系(NIL)以用于相关分子撑的研究,先前的研究认为,建立NIL所需回交次数一般为6次以上,本研究用RAPD分析证明了Rf3基因近等基因系创建的回交次数为4次,即达到与目标连锁片段的有效渗入。  相似文献   
83.
The ionic composition of the of the intracellular content of the alcohol yeast Saccharomyces cerevisiae R. 1039 biomass was studied for confirmation of their use perspectiveness as a mediator to enable the management the mineral content of food in the manufacture of food and feed additives. The ionic composition of the obtained extracts were identified using the method of capillary electrophoresis. It is found that the quantitative ion content in the cell extracts depends on the concentration of the nutrient medium. When the yeast S. cerevisiae R. 1039 was cultivated on the medium with the soluble solids concentration of 30%, the intracellular ion content in the extracts was 1.3 times higher than when the yeast was cultivated on 12% wort by increasing the concentration of chlorides, sulfates, formates, potassium ions, and calcium. The yield of the yeast S. cerevisiae R. 1039 biomass increased 1.6 times per unit of volume of the medium with increase of the soluble solids concentrations from 12% to 30%.  相似文献   
84.
Twelve anestrous adult Greyhound bitches were used to study a regimen for induction of estrus. Once daily, 7 bitches were given diethylstilbestrol (DES; 5 mg, PO) until sanguineous vaginal discharge and vulvar edema were observed (designated as day 1 of proestrus) and for 2 days thereafter. If no response was elicited after 7 days, a doubled DES dose was given for up to an additional 7 days. Luteinizing hormone (5 mg, IM) was given on day 5 of proestrus, and follicle-stimulating hormone (10 mg, IM) was given on days 9 and 11 of proestrus. Bitches were bred once on day 13. Five bitches were used as a control group; they were given candy tablets for 7 days (first day on tablets, treatment day 1) and 0.9% NaCl (1.0 ml, IM) on treatment days 12, 16, and 18. The 7 bitches treated with DES had a mean proestrus period of 7.7 days and a mean estrus period of 5.7 days up to the day of mating. After mating, they had a mean gestation interval of 64 days and delivered a mean of 4 pups/litter. In 5 bitches, initial treatment with 5 mg of DES/day induced proestrus within 7 days; however, in 2 bitches, additional treatment with 10 mg of DES/day was needed for 5 and 6 days, respectively. Serum estradiol-17 beta and progesterone concentrations remained at base line during the period of DES treatment. Concentrations of both hormones increased after injection with luteinizing hormone and remained high for the next 4 days.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
85.
86.
This study aimed to investigate the effects of dietary crude palm oil (CPO) on fatty acid metabolism in liver and intestine of rainbow trout. Triplicate groups of rainbow trout for 10 weeks at 13 °C were fed on diets in which CPO replaced fish oil (FO) in a graded manner (0–100%). At the end of the trial, fatty acid compositions of flesh, liver and pyloric caeca were determined and highly unsaturated fatty acid (HUFA) synthesis and fatty acid oxidation were estimated in isolated hepatocytes and caecal enterocytes using [1‐14C]18:3n‐3 as substrate. Growth performance and feed efficiency were unaffected by dietary CPO. Fatty acid compositions of selected tissues reflected the dietary fatty acid composition with increasing CPO resulting in increased proportions of 18:1n‐9 and 18:2n‐6 and decreased proportions of n‐3HUFA, 20:5n‐3 and 22:6n‐3. Palmitic acid, 16:0, was also increased in flesh and pyloric caeca, but not in liver. The capacity of HUFA synthesis from 18:3n‐3 increased by up to threefold in both hepatocytes and enterocytes in response to graded increases in dietary CPO. In contrast, oxidation of 18:3n‐3 was unaffected by dietary CPO in hepatocytes and reduced by high levels of dietary CPO in enterocytes. The results of this study suggest that CPO can be used at least to partially replace FO in diets for rainbow trout in terms of permitting similar growth and feed conversion, and having no major detrimental effects on lipid and fatty acid metabolism, although flesh fatty acid compositions are significantly affected at an inclusion level above 50%, with n‐3HUFA reduced by up to 40%.  相似文献   
87.
The effects of the addition of fatty acids, monoglycerides (MG), and wheat germ oil (WGO) on the level of crystallinity and the crystalline structure of extrusion-cooked wheat starch have been studied using twin-screw extruders. Measurements of water solubility and water absorption indices were made on the extrudates, together with specific mechanical energy (SME) consumption and die pressure for the extruder. MG and the fatty acids added to a level of 4% caused an increase in Vhydrate type crystallinity. WGO addition to a level of 8% caused no change in crystallinity, although the Ehydrate type was favored at lower moisture contents. All additives caused a decrease in SME and an increase or maximum in die pressure. WGO behaved differently than MG and fatty acids in that its addition caused the water solubility index and expansion to increase, as previously observed for other oils added to flours.  相似文献   
88.
Denitrification losses from puddled rice soils in the tropics   总被引:4,自引:0,他引:4  
Summary Although denitrification has long been considered a major loss mechanism for N fertilizer applied to lowland rice (Oryza sativa L.) soils, direct field measurements of denitrification losses from puddled rice soils in the tropics have only been made recently. This paper summarizes the results of direct measurement and indirect estimation of denitrification losses from puddled rice fields and reviews the status of research methodology for measurement of denitrification in rice fields. The direct recovery of (N2+N2O)-15N from 15N-enriched urea has recently been measured at sites in the Philippines, Thailand, and Indonesia. In all 12 studies, recoveries of (N2+N2O)-15N ranged from less than 0.1 to 2.2% of the applied N. Total gaseous N losses, estimated by the 15N-balance technique, were much greater, ranging from 10 to 56% of the applied urea-N. Denitrification was limited by the nitrate supply rather than by available C, as indicated by the values for water-soluble soil organic C, floodwater (nitrate+nitrite)-N, and evolved (N2+N2O)-15N from added nitrate. In the absence of runoff and leaching losses, the amount of (N2+N2O)-15N evolved from 15N-labeled nitrate was consistently less than the unrecovered 15N in 15N balances with labeled nitrate, which presumably represented total denitrification losses. This finding indicates that the measured recoveries of (N2+N2O)-15N had underestimated the denitrification losses from urea. Even with a probable two-or threefold underestimation, direct measurements of (N2+N2O)-15N failed to confirm the appreciable denitrification losses often estimated by the indirect difference method. This method, which determines denitrification losses by the difference between total 15N loss and determined ammonia loss, is prone to high variability. Measurements of nitrate disappearance and 15N-balance studies suggest that nitrification-denitrification occurs under alternate soil drying and wetting conditions both during the rice cropping period and between rice crops. Research is needed to determine the magnitude of denitrification losses when soils are flooded and puddled for production of rice.  相似文献   
89.
Zusammenfassung Die Nebenwirkung von Insektiziden auf die Lebensgemeinschaften der Kulturen ist desto tiefer und durchgreifender, um je dauerhaftere Kulturen es sich handelt. Obwohl in den Agrocoenosen Selbstregulation und Gleichgewicht fehlen, bestehen hier doch bedeutende quantitative Zusammenhänge zwischen Schädlingen und ihren Räubern und Parasiten. Diese Zusammenhänge werden an Beispielen von Hauptschädlingen der Hackfrüchte dargestellt.Es wird vorgeschlagen, schon bei der Prüfung von Insektiziden die Wirkungsweise des Insektizides auf die wichtigsten natürlichen Feinde von Schädlingen zu untersuchen.
Summary In the agrocoenoses the intensity of the side effects of insecticides is in proportion to the degree of permanency of the cultures. Although the agrocoenoses do not represent a self-regulated and balanced ecological unit, there are, however, quantitative correlations between the pests and their predators and parasites. These interrelations are demonstrated by examples from the main pests of the root crops.It is suggested that the effects of insecticides on the most important natural enemies of the pests be examined already in the testing stage of the insecticides.

Résumé Les effects secondaires des insecticides sur les agrocénoses sont d'autant plus importants et actifs qu'il s'agit de cultures permanentes. Bien que des régulations spontanées et l'equilibre manquent dans les agrocénoses, il existe done d'importants rapports quantitatifs entre les insectes nuisibles et leurs prédateurs et leurs parasites. Ces rapports seront illustrés par des exemples des principaux insectes nuisibles aux plantes sarclées.On propose d'étudier, dès la mise à l'essai des différents insecticides, le mode d'action de chaque insecticide sur les ennemis naturels les plus importants des insectes nuisibles.


mit 5 Fig.

Vortrag, gehalten am 4. September 1967 auf dem VI. Internationalen Pflanzenschutzkongress in Wien.  相似文献   
90.
Résumé On présente des données sur la persistence du DDT sur tomates, poivrons, et aubergines en plein champ, et sur tomates en serre, à la suite de l'application des traitements par concentrés émulsifiables. Dans le cas des tomates on a constaté que le dépôt résiduel est audessous de 1 ppm apres un intervalle de 11 jours depuis l'application du traitement en champ. En serre, et pour la même quantité de substance toxique, la persistence se maintient jusqu'à 36 jours.Le dépôt initial sur aubergines est plus élevé que dans le cas des tomates, atteignant jusqu'à 1 ppm. après environ 22 à 29 jours. Chez les poivrons, le résidu initial est très grand par rapport aux deux premières légumes et atteint 19 ppm. 22 Jours après le traitement celui-ci varie entre 0,8–1,3 ppm.Ensuite, on a étudié la dynamique de la répartition dans le temps de la substance toxique par unité de surface. Les résultats obtenus démontrent l'uniformité des traitements; la diminution de la quantité de substance toxique dans le temps est due autant au facteur croissance qu'aux conditions de climat.
Summary The paper deals with data on the persistence of DDT on tomatoes, sweet peppers and eggplants in the field, and on tomatoes in the greenhouse, following the application of emulsions. It is shown that in tomatoes, residual deposits are below 1 ppm 11 days after treatments in the field. In the greenhouse, the persistence is long-lasting, attaining up to 36 days when the same amount of toxicant is applied.In eggplants, the initial deposit is higher than in tomatoes attaining about 1 ppm after 22–29 days. In sweet peppers, the initial amount of residue is very large as compared to the first two vegetables and attains 19 ppm; 22 days after the treatement it ranges between 0.8–1.3 ppm.Besides, the dynamics of toxicant distribution with time, per area unit was studied. The data obtained demonstrate the uniformity of the treatments, and that the diminution of the amount of toxicant with time is due to both the growth factor and the climate conditions.

Zusammenfassung In diesem Beitrag werden Daten betreffs der Karenzzeit der DDT-Rückstände auf Tomaten, Paprika und Eierfrüchten nach Behandlung des Feldbestandes und auf Tomaten, die im Treibhaus mit DDT-Emulsionen behandelt wurden, wiedergegeben. Aus unseren Untersuchungen geht hervor, daß der Rückstandswert auf Tomaten 11 Tage nach der Behandlung des Feldbestandes weniger als 1 ppm beträgt. Im Treibhaus hingegen erstreckt sich die Karenzzeit (Verweildauer) bis auf 36 Tage unter Anwendung derselben Wirkstoffmenge.Auf den Eierfrüchten ist der anfängliche Rückstandswert größer als auf den Tomaten und erreicht nach ungefähr 22–29 Tagen Werte unter 1 ppm. Im Falle der Paprikaschoten sind die Rückstandswerte anfangs sehr hoch im Gegensatz zu den vorher genannten Gemüsesorten und zwar erreichen sie 19 ppm. Nach 22 Tagen verzeichnen wir hier Werte von 0,8–1,3 ppm.Anschließend verfolgten wir die Dynamik der Wirkstoffverbreitung im Verhältnis der Zeit zur Oberflächeneinheit.Die erzielten Ergebnisse deuten sowohl auf eine uniform durchgeführte Behandlungsweise hin als auch auf die Tatsache, daß der zeitliche Rückgang der Rückstandsmenge von Wachstum und Klimabedingungen abhängig ist.


avec 4 figs.  相似文献   
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