LOWLAND RICE GROWTH AND DEVELOPMENT AND NUTRIENT UPTAKE DURING GROWTH CYCLE     

N. K. Fageria  A. B. dos Santos 《Journal of plant nutrition》2013,36(12):1841-1852

Rice is a staple food for more than 50% of the world's population and the majority of the global rice is produced from a lowland ecosystem. A greenhouse experiment was conducted with the objective to study lowland rice (cv. ‘BRSGO Guara’) growth, development, and nutrient uptake patterns during growth cycle. Growth observations and plant analysis were performed at initiation of tillering (IT), active tillering (AT), panicle initiation (PI), booting (B), flowering (F) and physiological maturity (PM). Plant height, number of leaves per culm, number of tillers per plant and maximum root length and root dry weight increased in a quadratic fashion with increasing plant age. Similarly, shoot dry weight increased linearly during growth cycle of the cultivar ‘BRSGO Guara’. Concentration and accumulation of most of the macronutrients and micronutrients responded with a quadratic trend with the advancement of plant age. Plant growth parameters were significantly associated with shoot dry weight plus grain yield. Similarly, nutrient accumulation had a significant correlation with shoot dry weight plus grain yield, which indicated the importance of these nutrients in the lowland rice production.  相似文献   

Prediction of phosphorus uptake by a mechanistic model in a low phosphorus highly weathered soil as affected by mycorrhizae inoculation     

P. R. Ernani  J. C. P. Santos  J. Kaminski  D. S. Rheinheimer 《Journal of plant nutrition》2013,36(6):1067-1078

Mechanistic models need to be validated before being widely used. The Barber‐Cushman mechanistic nutrient uptake model has successfully predicted phosphorus (P) uptake in high‐P soils, but it has not been tested in soils with low available P. Some assumptions of this model (no influence of mycor‐rhizae and root hairs on nutrient uptake) may have different implications according to the soil P level. The objective of this study was to test the ability of the Barber‐Cushman model to predict P uptake for corn in an Oxisol with low P values as influenced by mycorrhizae inoculation. The experiment was carried out in a greenhouse, in a factorial with two levels of P (25 and 100 mg/kg), of limestone (pH 4.7 and 5.5), and of mycorrhizae inoculation (with and without). Observed P uptake was determined in the roots and in the shoots of 46‐day‐old corn plants. The predicted P uptake by the model was calculated using a computer program. There was a good agreement between observed and predicted P uptake (r² = 0.97). The model, however, underpredicted the amount of P taken up by corn plants, probably due to the contribution of root hairs. Inoculation with mycorrhizae did not affect corn yield and had a small influence on both observed and predicted P uptake. The model predicted, respectively, 31% and 41% of the P taken up by plants for treatments with and without mycorrhizae inoculation. Sensitivity analysis demonstrated that P in the soil solution and the rate of root growth were the parameters that most influenced predicted P uptake, and that plant uptake kinetics had a small contribution.  相似文献   

Rice and common bean growth and nutrient concentration as influenced by aluminum on an acid lowland soil     

N. K. Fageria  A. B. Santos 《Journal of plant nutrition》2013,36(5):903-912

Aluminum (Al) toxicity is a major limiting factor for crop production in many acid soils in Brazil. Two greenhouse experiments were conducted to evaluate response of rice (Oryza saliva L.) and common bean (Phaseolus vulgaris L.) to Al levels on a Low Humic Gley acid soil. The Al levels created by liming were: 0,0.03, 0.10, 0.23, 1.03, and 3.83 cmol_c kg^‐1 of soil. Rice dry matter and grain yield were significantly improved (P<0.05) with increasing Al levels in the soil solution. However, common bean dry matter as well as grain yield were significantly (P<0.01) decreased with increasing Al levels. At 3.83 cmol_c Al kg^‐1 of soil, bean did not produce any dry matter or grain yield. On an average, Al decreased nutrient concentrations in the tops of rice plant except zinc (Zn) and manganese (Mn), but in bean crop almost all the nutrients concentrations were increased with increasing Al levels. Rice showed tolerance to Al toxicity, whereas, common bean was susceptible to toxicity of this element. For successful intensive crops production lime application will be necessary in Varzea soils especially for legume production.  相似文献   

Long‐term changes in fishery resources of an estuary in southwestern Atlantic according to local ecological knowledge     

Vinni Santos Thykjaer  Lucas dos Santos Rodrigues  Manuel Haimovici  Luís Gustavo Cardoso 《Fisheries Management and Ecology》2020,27(2):185-199

Long‐term changes in the abundance of fisheries resources from the Patos Lagoon estuary and adjacent coastal waters in southern Brazil have been observed. Despite this understanding, it is well known that the perception of pristine state of the environment is susceptible to inter‐generational changes, commonly known as shifting baseline syndrome (SBS). An useful approach in the reconstruction of pristine scenarios and in lack of data, as often occurs in small‐scale fisheries, is the local ecological knowledge (LEK). Temporal changes in the perception of 81 fishers with 1–63 years of fishing about the resources status were analysed. More experienced fishers reported larger catches, heavier individuals and perceived a greater number of species as "scarce" nowadays and "common" at the beginning of their careers proving the existence of a SBS among them. Over time, the number of fishing sites with very high catches decreased and fishing sites shifted from the lower towards the upper estuary. The perception of the fishers corroborated the real decreasing scenario in estuarine fisheries resources shared with industrial fishing in coastal waters. The results reinforce the utility of LEK for reconstruction of biological scenarios when no empirically obtained data are available.  相似文献   

From the lab to the river: Determination of ecological hosts of Anodonta anatina     

Ana Rita Dias  Amílcar Teixeira  Manuel Lopes‐Lima  Simone Varandas  Ronaldo Sousa 《水产资源保护:海洋与淡水生态系统》2020,30(5):988-999

1. Coextinction is the simplest form of secondary extinction and freshwater mussels (Bivalvia, Unionida) may be particularly prone to this phenomenon as their life cycle includes an obligatory parasitic larval stage on fish hosts.
2. The main aims of this study were to determine the possible ecological fish hosts of Anodonta anatina (Linnaeus, 1758) in several rivers of the Douro basin in northern Portugal and to assess possible spatial and temporal differences in glochidial (larval) loads. In order to achieve this, electrofishing was conducted from December to April, the fish fauna was characterized, and levels of infestation with A. anatina glochidia were determined.
3. Native cyprinid species, mainly Luciobarbus bocagei (Iberian barbel) and Squalius carolitertii (northern Iberian chub), together with the non‐native Lepomis gibbosus (pumpkinseed sunfish) and Alburnus alburnus (common bleak), were found to have the highest glochidial loads. Clear differences in infestation between rivers and throughout time were detected, with an infestation period from January to March, and with the Tâmega River having the highest prevalence.
4. Anodonta anatina is able to infest a variety of fish species, and this together with earlier studies showed that the metamorphosis into juveniles occurs mainly in native cyprinid species, although non‐native species like common bleak can also be considered suitable hosts. However, the larvae infesting other non‐native species, such as the pumpkinseed sunfish, do not metamorphose and can be considered ‘dead ends’.
5. Overall, the results reported here are important for the conservation of A. anatina (and other unionoid species) because several Iberian rivers (and worldwide) have been subjected to the extirpation of native fish species and the introduction of non‐native fish species. Therefore, careful assessments of fish communities should be conducted to assess possible negative interactions with freshwater mussels.

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Developing the harpacticoid copepod Tisbe biminiensis culture: testing for salinity tolerance, ration levels, presence of sediment and density dependent analyses     

Lília P Souza-Santos  Julia M O Pastor  Natasha G Ferreira  Weruska M Costa  Cristiane M V Araújo-Castro  & Paulo J P Santos 《Aquaculture Research》2006,37(15):1516-1523

Copepods have a number of advantages for use as live food in cultures of fish and crustacean larvae. This study aimed to develop culture techniques of Tisbe biminiensis Volkmann‐Rocco 1973 in volumes of 500 mL. The first experiment tested the effect of salinity on survival and fecundity. The other experiments studied the population growth comparing two levels of daily ration and the effect of sand sediment in cultures. The cultures were carried out on plastic boxes at 29°C, salinity of 34 g L^?1 and 12 h light/12 h dark photoperiod with aerated filtered seawater, total renewal every other day. Adult females tolerated the decrease of salinity from 34 to 27 g L^?1 but the offspring production decreased significantly. The salinity of 20 g L^?1 was not tolerated at all. Tisbe biminiensis attained one of the highest rates of increase in cultures among harpacticoids (0.33 day^?1) and a high density of 205 individual ind. mL^?1. The carrying capacity of the population was estimated as 67 200 ind. in 500 mL recipients. In conclusion, T. biminiensis grow fast and attain high densities in cultures of 500 mL volume without sediment, feeding a daily ration of 50–100% of copepodite biomass.  相似文献   

Regional and local environmental correlates of native Iberian fish fauna   总被引：2，自引：0，他引：2  

M. T. Ferreira  L. Sousa  J. M. Santos  L. Reino  J. Oliveira  P. R. Almeida  R. V. Cortes 《Ecology of Freshwater Fish》2007,16(4):504-514

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Microhabitat use by Iberian nase Chondrostoma polylepis and Iberian chub Squalius carolitertii in three small streams, north-west Portugal   总被引：2，自引：0，他引：2  

J. M. Santos  F. N. Godinho  M. T. Ferreira 《Ecology of Freshwater Fish》2004,13(3):223-230

Abstract –  Microhabitat use of Iberian nase Chondrostoma polylepis (Steindachner 1865) and Iberian chub Squalius carolitertii (Doadrio 1988) was studied in three small streams of the Lima basin, north-west Portugal. Measurements were made for 210 and 248 individuals, respectively, distributed in two size classes, based on fish ages, during winter, spring, summer and autumn 1998. Both species moved to shallow and slow-flowing microhabitats in summer and autumn, but this mainly reflected seasonal variation in microhabitat availability. Larger individuals of both species used deeper and lower percentage cover areas than smaller conspecifics, however significant ontogenetic differences were only found for water velocity. Different patterns of nonrandom microhabitat use were displayed by both cyprinids. Larger I. nase were in deeper and more discovered waters than those available in the habitat, whereas I. chub was over-represented in slow-flowing areas. There was no evidence of interspecific competition for microhabitat, therefore it is unlikely that spatial resource was limited during the present study.  相似文献   

Feeding,growth, and blood chemistry of the tambaqui (Colossoma macropomum) held under self-feeding and time-restricted automatic feeding conditions     

Guilherme  Helder O.  Santos  Fabio A. C.  Costa  Leandro S.  Prado  Verônica G. L.  Palheta  Glauber D. A.  de Melo  Nuno F. A. C.  Luz  Ronald K.  Ribeiro  Paula A. P. 《Aquaculture International》2022,30(1):323-339

This work evaluated the effects of food frequencies and self-feeding on the behavior, performance, and blood biochemistry of Colossoma macropomum. Juveniles weighing 3.63?±?0.05 g were distributed in 27 aquariums (40 L), with six fish per aquarium, to evaluate nine treatments in three replications in a 12L:12D photoperiod. The treatments were 24-h self-feeding (SF); daytime self-feeding at will (SFD); nighttime self-feeding at will (SFN); and feeding at fixed frequencies of two (2D), four (4D), and six times (6D) daytime and twice (2 N), four (4 N), and six times (6 N) nightly. The treatments were offered in automatic feeders, with fixed frequencies programmed. Extruded commercial feed, with 46% protein, was used. The experimental period was 40 days. In the SF treatment, the animals exhibited 95.7% nocturnal and 4.3% diurnal feeding activity (p?<?0.05). In the treatment SFD and SFN, the animals showed feeding activity throughout the day and night. Final weight, weight gain, and total feed intake were higher for animals at fixed daytime and nighttime frequencies (p?<?0.05). Feed conversion was better for animals in SF, SFD, 4D, SFN, and 4 N (0.89, 0.76, 0.91, 0.85, and 0.88, respectively) (p?<?0.05). Cholesterol and high-density lipoproteins were lower for fish in SF, SFN, 2 N, 4 N, and 6 N (p?<?0.05). SF treatment animals had lower triglyceride content, 154.20 mg dL^?1 (p?<?0.05). Colossoma macropomum has nocturnal food preferences, however, with remarkable plasticity. Juveniles of this species fed four times during the day or night show good performance. Dietary patterns influenced the blood metabolic indicators of this species and the periods studied.

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Electrocardiographic evaluation of the degree of sedation and the isolated use of methadone in healthy dogs     

Thais M Menegheti  Juliana T Wagatsuma  Acácio D Pacheco  Beatriz Perez  Cynara M Pacheco  Caio JX Abimussi  Paulo PS dos Santos  Valéria NL de Souza Oliva 《Veterinary anaesthesia and analgesia》2014,41(1):97-104

ObjectiveThe present study aimed to investigate the influence of methadone on cardiorespiratory parameters, electrocardiogram and clinical sedation in dogs. Further possible side effects are reported.Study designProspective experimental cross-over study.DogsEight, 1–4-year-old, various breeds of dogs of both genders weighing 9–36 kg.MethodsEach dog was treated three times: methadone 0.3 mg kg^?1 (M0.3), 0.5 mg kg^?1 (M0.5) and 1.0 mg kg^?1 (M1.0) intramuscularly. Respiratory rate, heart rate and arterial blood pressure were recorded as well as electrocardiographic evaluation of lead II. Clinical sedation in each treatment received a score (0–3) after drug administration and at 30 minute intervals until scores and measurements returned to baseline values.ResultsA significant decrease in heart rate was seen with each dose of methadone and bradycardia (HR<60 bpm) was noted in a few dogs at each dose. A clinically significant arrhythmia occurred in one dog at 1 mg kg^?1 that required reversal with butorphanol. There was no significant difference in SAP, MAP and DAP between treatments. Some side effects such as salivation, defecation, vocalization and panting, after administration of methadone were observed. There were no differences in mean values of heart rate, P-wave and QRS complex duration and QT interval between treatments.Conclusion and clinical relevanceMethadone administration was associated with panting and a decrease in heart rate at all doses tested in this study. The cardiac rhythm should be monitored carefully in dogs when methadone is administered on its own, especially at higher doses.  相似文献