Pesticide residue levels in peppers grown in a greenhouse after multiple applications of pyridaben and tralomethrin

Residue levels of pyridaben and tralomethrin were determined in peppers grown in an experimental greenhouse, during a 4 week period in which up to four successive treatments with both pesticides were applied. In all cases, plants were sprayed with a mixture of pyridaben and tralomethrin at application rates of active ingredients of 140 and 36 g/ha, respectively. Sampling was carried out at 1, 3, 7, 8, 10, or 14 days after each multiple application, simulating the typical harvesting practices in greenhouse plantations. Residue levels of pyridaben and tralomethrin were determined by using ethyl acetate extraction and GC-ECD. During the study, residue levels in the plantation ranged between 0.22 and 0.04 mg/kg for pyridaben and between 0.09 and 0.02 mg/kg for tralomethrin, with median values of 0.14 and 0.06 mg/kg, respectively. These values represent 28 and 600%, respectively, of the corresponding maximum reside limits currently established in Spain. The application of an intensive washing process to the pepper samples did not lead to a significant reduction of the residue level of either pesticide. Likewise, no significant differences were found between the residue levels in the "edible" and "inedible" parts of the peppers.     

The Effect of Legume Species Grown as Cover Crops in Olive Orchards on Soil Phosphorus Bioavailability

Some legume species are able to utilize phosphorus (P) from sparingly soluble P sources benefiting companion crops or those following in the rotation. Lupinus albus, Vicia villosa, and a mixture of eleven annual pasture legumes were used in olive orchards as mulched cover crops as a means of increasing the soil P availability. By soil testing and growing bioindicator P plants in the next season, it was possible to detect a slight but consistent increase in soil P availability. The results indicated that the increase in soil P availability was mainly due to the mineralization of the high P content legume residues, rather than the direct effect in the rhizosphere of the living plants. The results also suggested that the good adaptation of white lupine to low P environments might be due to a high internal P use efficiency of this species, producing high dry matter yields with low P concentration in their tissues.     

Effect of intravenous lidocaine on isoflurane MAC in dogs

Lidocaine decreases minimum alveolar concentration (MAC) of inhalational anesthetics. This study determined the influence of a low dose, 50 µg kg^?1 minute^?1 (LDI) and high dose, 200 µg kg^?1 minute^?1 (HDI) constant rate infusion of lidocaine on the MAC of isoflurane (I) in dogs. Ten mongrel dogs were anesthetized with I in oxygen and mechanically ventilated. End‐tidal anesthetic (Fe ′A) and CO₂ (Pe ′CO₂) concentrations were monitored at the endotracheal tube adaptor with an infrared gas analyzer calibrated before each experiment with a standardized calibration gas mixture designed for the analyzer. Pe ′CO₂ and body temperature were maintained within normal limits. Noxious stimuli included clamping the hindlimb paw (HC) and electrical current (50 V at 50 cycles second^?1 for 10 milliseconds pulse^?1) applied subcutaneously to the forelimb (FE) at the level of the ulna. After an initial equilibration period of at least 40 minutes at an Fe ′A of 1.7%, the Fe ′A was decreased to a value close to the estimated MAC for dogs. MAC was defined as the Fe ′A mid‐way between the value permitting and preventing purposeful movement. Following baseline MAC, a loading dose of 2 mg kg^?1 of lidocaine IV was administered over 3 minutes followed by the LDI, and MAC determinations for the combination started after 30 minutes of infusion. Once determined, the lidocaine infusion was stopped for 30 minutes and the dog maintained at the ETC that prevented movement without the lidocaine. Following this period, a second loading dose of lidocaine was given (2 mg kg^?1) over 3 minutes followed by the HDI, and the MAC determination procedure repeated after 30 minutes of infusion. Data were analyzed using an anova for repeated measures. MAC of I was 1.34 ± 0.035% (mean ± SEM) for both the FE and HC stimuli. The LDI significantly decreased MAC to 1.09 ± 0.043% (18.7% reduction) and HDI to 0.76 ± 0.030% (43.3% reduction). In conclusion, lidocaine infusions decreased the MAC of isoflurane in a dose‐dependent manner.     

Comparison of the hemodynamic effects of halothane alone and halothane combined with epidurally administered morphine for anesthesia in ventilated dogs

The hemodynamic effects of 1.5 minimal alveolar concentration of halothane alone (1.6% end-tidal) and 1.5 minimal alveolar concentration of halothane (1.1% end-tidal concentration) combined with epidurally administered morphine were compared during controlled ventilation in 10 dogs used on 2 occasions and randomly allocated to 2 groups. Arterial blood pressure, cardiac index, stroke volume, left ventricular work, and pulmonary arterial pressure were significantly (P less than 0.05) higher in dogs of the morphine-treated group before administration of morphine. After epidural administration of morphine (0.1 mg/kg of body weight diluted in 0.26 ml of saline solution/kg), hemodynamic changes were not observed, and the aforementioned variables remained significantly (P less than 0.05) higher than values in dogs of the halothane only group. Compared with halothane (1.6%) alone, the reduction in halothane end-tidal concentration (1.1%) associated with epidurally administered morphine is beneficial in maintaining hemodynamic function.     

Pseudomonas spp. isolates with high phosphate-mobilizing potential and root colonization properties from agricultural bulk soils under no-till management

Seven phosphate-mobilizing pseudomonads were isolated, identified, and characterized in terms of their biofertilizer potential and root-colonizing properties. Pseudomonas protegens (ex-fluorescens) CHA0 was used for comparative purposes. Four isolates (LF-MB1, LF-P1, LF-P2, and LF-P3) clustered with members of the “Pseudomonas fluorescens complex,” whereas the other three (LF-MB2, LF-V1, and LF-V2) clustered with members of the “Pseudomonas putida/Pseudomonas aeruginosa complex.” Assays in buffered liquid growth medium supplemented with tricalcium phosphate enabled the separation of the isolates into two groups: group A (LF-P1, LF-P2, LF-P3, and LF-V1) solubilized P from 151 up to 182?μg?mL^?1, and group B (LF-MB1, LF-MB2, and LF-V2) solubilized less than 150?μg?P?mL^?1. All isolates displayed acid and alkaline phosphatase activities. With the exception of LF-MB2, all isolates were able to degrade phospholipids from lecithin. Additionally, all isolates exhibited extracellular protease activity, and four isolates produced hydrogen cyanide, two traits that are related to biocontrol of phytopathogens. To study root colonization in non-sterile soil, isolates were doubly tagged with gfp and a tetracycline resistance cassette. After 15?days of competition with the indigenous bacterial flora, all tagged isolates colonized soybean roots at counts ranging from 7.6?×?10⁵ to 1.7?×?10⁷?CFU?g^?1. The results indicate that there are already efficient phosphate-mobilizing pseudomonads adapted to agricultural bulk soils under no-till management in Argentina and thus having excellent potential for use as biofertilizers.     

Influence of native or exotic trees on soil fertility in decades of silvopastoral system at the Brazilian savannah biome

Silvopastoral systems (SPSs) are considered a conservationist system by combining forestry species cultivation with domesticated grazing animals, intercropping trees, and pasture in the same area. SPSs are noun for its contribution to improve soil chemical and physical properties, enhance grass nutritional status, provide healthier animal environment, and increase farmers’ options to maximize the use of land. In soil degraded areas, such as those found in Brazilian savannah biome (BSB), the SPSs constitute an alternative to soil recuperation in these areas. Therefore, our aim was to assess soil fertility attributes at different depths on a BSB grown with Brachiaria brizantha cv. Marandu grass, the influence of SPS with native tree zeyheria (Zeyheria tuberculosa) settled in 1984, or with the exotic eucalyptus (Eucalyptus grandis) settled in 1994. The soil water pH, P, Ca, Mg, and K contents, as well as soil base sum and saturation, were found superior mostly at the top layer (0–2 cm) of the eucalyptus site, than for the ipê-felpudo site. This response was correlated to greater soil organic matter and carbon at the eucalyptus site, which demonstrated to have high nutrient cycling rates. Around 50 % of the CEC in both SPSs was occupied by bases, demonstrating that the areas have large potential to absorb applied nutrients. The SPSs have no significant impact on S-SO₄ ^2? or micronutrient availability. The litter composition in eucalyptus site was accountable for the superior results of this SPS, which has shown as a promising choice for land use and conservation in the BSB.     

Sufficiency ranges and crop nutrient removals for peppermint (Mentha X piperita L.) established from field and pot fertilizer experiments

Peppermint is an important aromatic and medicinal plant used across the world in pharmaceutical, cosmetic and food industries. However, there is a lack of agronomic research on this crop which hinders the implementation of best agricultural practice at farm level. Plant analysis, for instance, cannot be used as a tool to implement a suitable fertilizer recommendation program, since sufficiency ranges and crop nutrient removals have not yet been established. Thus, the main objectives of the present work were to assess the response of peppermint to varying nitrogen (N), phosphorus (P), potassium (K) and boron (B) rates, to establish sufficiency ranges from macro, micronutrients and SPAD-readings and to estimate crop nutrient removals in the aboveground biomass. Field trials and pot experiments were conducted from 2013 to 2015 in a wide range of conditions involving 12 N, P, K or B fertilizer trials and a total of 48 cuts of biomass. Nitrogen fertilization increased dry matter yield of peppermint on the vast majority of sampling dates. In contrast, P, K, or B did not produce a significant effect on dry matter yield in any of the experiments. The sufficiency ranges set for macronutrients N, P, K, Ca and Mg are respectively 32.0 – 42.0, 1.2 – 4.5, 10.0 – 30.0, 7.0 – 23.0, and 4.0 – 10.0 g kg^?1. Those for micronutrients B, copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) are respectively 20 – 200, 5 – 25, 100 – 600, 25 – 300, and 30 – 200 mg kg^?1. Sufficiency range for SPAD-readings is 45 – 50 SPAD units. All these ranges were established for the commercial harvesting date. The amounts of N, P, K, calcium (Ca), and magnesium (Mg) removed in aboveground biomass are respectively 22.7, 1.6, 26.4, 16.4 and 4.8 kg Mg^?1 of dry biomass.     

Sufficiency ranges for lemon balm and nutrient removals in aboveground phytomass

A set of fertilizer experiments were conducted during three growing seasons with the aim of establishing sufficiency ranges and crop nutrient removals for Melissa officinalis L. Critical nutrient concentrations were determined by the Cate–Nelson method or by removing 10% of extreme high and low values, respectively if a positive response to a given nutrient was recorded or not. Sufficiency ranges for macro, micronutrients, and SPAD-readings were set as: 27.0–40.0 g N kg^?1; 0.8–2.7 g P kg^?1 (May–August); 1.5–3.8 g P kg^?1 (September–November); 10.0–25.0 g K kg^?1 (May–August); 18.0–32.0 g K kg^?1 (September–November); 5.0–25.0 g Ca kg^?1; 3.5–8.5 g Mg kg^?1; 18–125 mg B kg^?1; 5–25 mg Cu kg^?1; 75–500 mg Fe kg^?1; 20–300 mg Zn kg^?1; 30–250 g Mn kg^?1; 30–45 SPAD-units. These results will allow laboratories to use plant analysis as an important tool in improving the fertilizer recommendations for this species.     

Extraction and electrophoretic analysis of large dsRNAs from desiccated plant tissues infected with plant viruses and biotrophic fungi

Extraction and electrophoretic analysis of large dsRNAs from plant and fungal tissues has been used successfully to detect RNA viruses infecting plants, fungi, and oomycetes. We modified a previously reported dsRNA extraction protocol and used it to detect a wide variety of plant and putative fungal viruses from infected plant tissues. The modified protocol was used successfully to extract large dsRNAs from 50 to 70 mg of desiccated plant tissues infected with acute and persistent RNA viruses and from plant tissues infected with biotrophic fungi causing rusts and powdery mildew diseases. The protocol proved to be efficient, fast, economic and versatile and requires relatively small amounts of desiccated tissue.