Should we use meshes or solid tube shelters when planting in Mediterranean semiarid environments?     

Oliet  Juan A.  Blasco  Raul  Valenzuela  Patricio  Melero de Blas  María  Puértolas  Jaime 《New Forests》2019,50(2):267-282

New Forests - Tree shelters in Mediterranean environments have a two-sided effect. They not only protect seedlings from browsing but also ameliorate microclimatic conditions, improving...  相似文献   

Long-term changes in willow spatial distribution on the elk winter range of Rocky Mountain National Park (USA)     

Peinetti  H. Raul  Kalkhan  Mohammed A.  Coughenour  Michael B. 《Landscape Ecology》2002,17(4):341-354

We determined changes in willow (Salixspp.) cover in two valleys of the eastern slope of Rocky Mountain National Park,Colorado, USA, and related these changes to suspected causative factors. Changes in vegetation were inferred from digital maps generated from aerial photo-interpretation and field surveys conducted with a global positioning system. The decrease in riparian shrub cover was approximately 20% in both valleys over the period between 1937/46 and 1996, while the decline in tall willow (> 2 m tall) cover was estimated to be approximately 55%in both valleys. Suppressed willows (< 1.5 m tall) were predominantly located in areas affected by flooding and in areas where major river reductions were observed. Both valleys had sites that were being colonized by willows in wet meadows, and open areas created by flood disturbance. The potential causes of willow decline are many. Willow decline was associated with simplification of river spatial pattern, i.e., less complex branching and channelization, and a large flood disturbance. The causes of the reduction in river meanders were not determined, but are likely related to a decline in beavers, an increase in elk, and, possibly climate change. An increase in elk placed increased browsing pressure on willow during the period of the willow decline. Other factors such as climate changes and human activities could have also contributed to the willow decline. The persistence of these riparian ecosystems depends in large part on biotic interactions, particularly between willow, beaver, and elk. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Brassinosteroid analogue effects on the yield of yellow passion fruit plants (Passiflora edulis f. flavicarpa)     

Mara de Menezes Assis Gomes  Eliemar Campostrini  Nilton Rocha Leal  Alexandre Pio Viana  Tiago Massi Ferraz  Luciane do Nascimento Siqueira  Raul Castro Carriello Rosa  Alena Torres Netto  Miriam Nuñez-Vázquez  Marco António Teixeira Zullo 《Scientia Horticulturae》2006

The effects of successive brassinosteroid analogue (BR) applications (0.1 mg l⁻¹ of brassinosteroid analogue BB-16) were evaluated on commercial yellow passion fruit (Passiflora edulis f. flavicarpa) orchards in the first year of production. The treatments applied were: control, BR-1 (1 BR application shortly after the first flowers appeared), BR-2, BR-3, BR-4 and BR-5 (BR application in two, three, four and five consecutive weeks after the appearance of the first flowers, respectively). The fruits were collected for seven consecutive weeks (105 fruits treatment⁻¹) and fruit mass, length and diameter, soluble solid contents; pulp mass and peel thickness were evaluated in the laboratory. Multivariate analysis was performed in order to determine whether there were differences among the treatments taking into account all the measurements made. BR-3 was the most promising treatment because it produced the highest number of fruits plant⁻¹ (81.5) compared to the control (53.5) and the soluble solid content was 1 °Brix greater than the control. The BR-3 treatment resulted in a 65% increase in the estimated yield of the passion fruit plants, corresponding to 20 t ha⁻¹ compared to the control yield of 12 t ha⁻¹. The results showed that BB-16 sprayed during a period of reproductive development can increase the number of fruits per plant.  相似文献   

Protein digestibility, protease activity, and post-embryonic development of the velvetbean caterpillar (Anticarsia gemmatalis) exposed to the trypsin-inhibitor benzamidine     

Anderson M. Pilon  Raul Narciso C. Guedes 《Pesticide biochemistry and physiology》2006,86(1):23-29

Protein digestibility, proteolytic activity, and post-embryonic development of Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae) were assessed in larvae reared on artificial diet containing 0.00, 0.25, 0.50, and 0.75% (w/w) of the synthetic trypsin inhibitor benzamidine. Diet consumption was affected by the inhibitor when the insects were exposed to 0.50% benzamidine showing a 4-day delay and a 70%-higher peak of consumption. Larva weight gain was also affected by benzamidine and again the results of 0.50% benzamidine were unexpected due to the worst performance of the insects at this inhibitor concentration and not at 0.75% benzamidine. These patterns of consumption and weight gain were however consistent with the results of protein digestibility, which affects larvae mortality and adult emergence. The insect proteolytic activity was also affected by benzamidine, particularly at 0.50%. These results indicate that the insects are able to circumvent the potentially harmful effects of the inhibitor since at the highest concentration the negative impact is mitigated.  相似文献   

Fundamental considerations about design and sample size in strain comparisons and their implications     

Raul W Ponzoni  Nguyen Hong Nguyen  Hooi Ling Khaw 《Aquaculture Research》2011,42(12):1855-1858

Well‐known formulae for the calculation of the necessary number of animals in strain comparisons are presented. Their use is illustrated with an example with fish. Use of the formulae in the planning and design of strain comparisons is recommended. When the necessary number cannot be attained and the experiment is conducted with fewer animals than what the formulae indicate, or the animals originate from a low and thus most likely non‐random sample of parents, no inferences should be drawn about any observed between strain differences.  相似文献   

The performance and impact of a bubble-wash bead filter in a recirculating green water larval culture system for delta smelt (Hypomesus transpacificus)     

Tien-Chieh Hung  Raul H. Piedrahita 《Aquacultural Engineering》2011,45(2):60-65

Delta smelt are cultured at the UC Davis Fish Conservation and Culture Lab (FCCL) for research purposes. The culture systems used are based on recirculation technology to ensure optimum water quality for the fish at each life stage. Larval culture takes place in recirculation systems with green water to which a Nannochloropsis algal concentrate is added to maintain a turbidity of approximately 9 NTU. A bubble-wash bead filter is used to remove total suspended solids (TSS) from the recirculation system. The performance of the bubble-wash bead filter has been evaluated by testing the TSS and particle size distribution in two parallel systems operated in the same way. The need for bubble-wash bead filter backwashing and the impact of the backwash method were evaluated also.The results show that the bubble-wash bead filter removed a great deal of the TSS, including the algae added to maintain the turbidity. An improper backwash method could result in a short term but significantly high TSS peak in the system immediately after the backwash event. Testing over an extended filtration period with a prolonged backwash interval showed that the TSS in the system remained stable up to 150 h post backwash, at which time it increased rapidly. The TSS accumulation in the system with a bubble-wash bead filter that was not backwashed was greater than that in a parallel system without a bubble-wash bead filter. No significant mortality increase was found in the system without a bubble-wash bead filter for 34 days, which provides a possible alternative in order to lower the rearing cost. Nevertheless, there are benefits of using a bead filter, and these are discussed in the paper.  相似文献   

Routine oxygen consumption rates of california halibut (Paralichthys californicus) juveniles under farm-like conditions     

German E. Merino  Raul H. Piedrahita  Douglas E. Conklin 《Aquacultural Engineering》2009,41(3):166-175

Fish oxygen requirement is a fundamental variable of aquaculture system design and management, as it is the basis for determining water flow rates for sustaining stock. A study on oxygen consumption of California halibut (Paralichthys californicus) between 3.2 and 165.6 g was conducted in small raceways (2.41 m long, 0.28 m wide, and 0.22 m high; operational water depth between 0.05 and 0.10 m with a quiescent zone 19 cm long in the effluent section) working as open respirometers in a recirculating system under farm-like conditions. The fish were fed commercial dry pelleted feeds at a ratio of ～0.70–3.00% of body weight (BW) and stocked at densities between 94% and 316% percent coverage area (PCA). Oxygen consumption rates were determined by mass balance calculations. The mean and maximum oxygen consumption rates (g O₂/kg fish/day) for juvenile California halibut under the conditions tested can be expressed by M_day = 15.077W^?0.2452 and M_day = 17.266W^?0.2033, respectively, where W is fish weight in grams. The determination of oxygen consumption by California halibut in farm-like conditions provides valuable information on the oxygen requirement of these fish in an aquacultural setting. This information can be used for designing and sizing a rearing facility for the intensive culture of California halibut.  相似文献   

Evaluation of carbohydrate/lipid ratios on growth and metabolic response in tropical gar (Atractosteus tropicus) juvenile     

Rocío Guerrero‐Zrate  Carlos A. lvarez‐Gonzlez  Ronald Jesus‐Contreras  Emyr S. Pea‐Marín  Rafael Martínez‐García  Mario A. Galaviz  Lus M. Lpez  Raul Llera‐Herrera 《Aquaculture Research》2019,50(7):1812-1823

Five experimental diets with different carbohydrates/lipid ratio (CHO:L, 0.75, 1.28, 2.10, 2.52, 4.63) were formulated. Fish were randomly assigned by triplicate (10 fish per tank, 0.50 ± 0.01 g). Growth was registered every 15 days until end of the experiment (45 days). Samples were taken for analysis of chemical carcass composition, blood chemistry, glycogen and lipid liver content, digestive and metabolic enzyme activities. Results showed that survival, growth performance parameters and plasma glucose were not affected by treatments (p > 0.05). Lipids of carcass and liver, as well as triglycerides and plasma cholesterol increase significantly as CHO:L ratio decreased. While an inversely proportional tendency was observed for carcass protein and liver glycogen (p < 0.05). Digestive enzymes did not show significant differences among treatments (p > 0.05). Finally, Hexokinase (HK), glucokinase (GK), phosphoenol pyruvate carboxykinase (PEPCK) and fructose‐1,6‐biphosphase (FBPase) showed high regulation by carbohydrates up to the CHO:L ratio of 2.10 (p < 0.05), while pyruvate kinase (PK) activity was not significantly affected by the CHO:L ratio. By the other side, glucose‐6‐phosphate dehydrogenase (G6PD) tends to significantly increase as the CHO:L ratio increases. We conclude that A. tropicus fry have a high capacity to utilize carbohydrates substituting lipids as energy source in balanced diets.  相似文献   

Patterns of insecticide resistance in Aedes aegypti: meta‐analyses of surveys in Latin America and the Caribbean     

Raul Narciso C Guedes  Kaley Beins  Dennis Navarro Costa  Giovanini E Coelho  Haroldo Srgio da S Bezerra 《Pest management science》2020,76(6):2144-2157

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Trade‐off and adaptive cost in a multiple‐resistant strain of the invasive potato tuber moth Tecia solanivora     

Yeisson Gutirrez  Tito Bacca  Lady S Zambrano  María Pineda  Raul NC Guedes 《Pest management science》2019,75(6):1655-1662

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