randomized experimental design
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Ana P. da Silva ◽  
Ricardo F. Marques ◽  
Antônio C. da Silva Junior ◽  
Sidnei R. de Marchi ◽  
Dagoberto Martins

ABSTRACT Information about the impact of herbicides in the soil based on the growth of bioindicator species is extremely useful in developing crop management strategies. Therefore, this study aims to evaluate the leaching potential of the herbicide S-metolachlor under different natural precipitations in medium-textured Oxisol using bioindicator plants. A completely randomized experimental design was adopted, with four replicates and treatments arranged in a 3 × 8 factorial scheme [three indexes of precipitation occurred in the environment before the collection of the samples (50, 91, and 131 mm) and eight depths in the soil profile (0-0.03; 0.03-0.06; 0.06-0.09; 0.09-0.12; 0.12-0.15; 0.15-0.20; 0.20-0.25; 0.25-0.30 m)]. PVC columns were used, maintaining the original soil integrity during sampling after accumulating the stipulated natural precipitation. Longitudinal sections separated the columns to sow the bioindicator species (cucumber, lettuce, Alexander grass, and sorghum). The phytotoxicity symptoms of bioindicator plants were evaluated, adopting a phytotoxicity visual scale between 0 and 100%, at 5, 7, 9, and 11 days after seeding. The responses of the bioindicator species to the residual effect of the herbicide S-metolachlor were variable and depended on the rainfall level. Generally, in a medium-textured Oxisol, the higher values of concentration of S-metolachlor occurs in depths ranging between 0 and 0.06 m. The maximum leaching depth detected was 0.12-0.15 m with 131 mm of precipitation. Cucumber was the most sensitive species to the presence of S-metolachlor in an Oxisol of medium-texture since it presents symptoms of phytotoxicity at higher depths.

2023 ◽  
Vol 83 ◽  
M. G. Barbosa ◽  
S. A. Souza ◽  
T. P. P. André ◽  
A. D. S. Pontes ◽  
C. S. Teixeira ◽  

Abstract The possible interference of resistant pest’s populations to insecticides in natural enemies in the action thas not been clarified yet. Thus, this study aimed to evaluate Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) performance on Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) eggs with resistance frequency to the Metaflumizone over six generations of product exposure. Egg cards (2.0 x 7.0 cm) containing eggs from two populations of S. frugiperda, (resistant to Metaflumizone and the other susceptible), were exposed to T. pretiosum females for 24 hours in free-choice and no-choice testing in three generations (G1, G4, and G6). A completely randomized experimental design was used with 25 replications, each consisting of an egg card (experimental unit) containing 20 eggs. The parameters evaluated were: parasitism (%), emergence (%), sex ratio, number of emerged parasitoids per egg and males/females longevity. ANOVA and Tukey test (P≤ 0.05) were applied on the results. Results showed a reduction in parasitism [41.0% (G1) and 28.4% (G4)], egg emergence (17.5%) and parasitoids/egg [16.2 (G4) and 17.2 (G6)] in eggs originating from the population with resistance frequency. Females emerging from G6 populations eggs without exposure to Metaflumizone had greater longevity (3.5 days more) than the resistant population. The sex ratio and male longevity were not affected. The results indicate a reduction in T. pretiosum activity if S. frugiperda populations have some frequency of resistance to Metaflumizone.

D. M. Pereira ◽  
E. M. Santos ◽  
J. S. Oliveira ◽  
F. N. S. Santos ◽  
R. C. Lopes ◽  

Abstract The current study aimed to evaluate the effects of cactus pear as a moistening additive on fermentative and microbiological characteristics, aerobic stability (AS), chemical composition and in situ rumen degradability of corn grain silage at different opening times. A completely randomized experimental design was adopted in a 4 × 3 factorial scheme with four levels of dry matter (DM) (50; 60; 70 and 80% of DM) and three opening times (30; 60 and 120 days after ensiling), with four replications. There was an effect of interaction (P < 0.05) between the DM levels and opening times on silage yeast population, effluent losses, gas losses, dry matter recovery (DMR), AS of the silage and on lactic acid bacteria, mould and yeast populations after AS trial. The 60% DM level presented DMR values above 930 g/kg of DM. However, the lowest AS time (96.52 h) was observed in silages with 60% DM at 60 days after ensiling, although all silages have shown high AS. The DM in situ degradability of the ensiled mass increased after the ensiling process at all DM levels and opening times, with the 60% DM content showing the best result. When using cactus pear as a corn grain moistening additive, the 60% DM level is recommended when the opening time is up 120 days.

Arturo Hernández-García ◽  
J. Zavala-Ruiz ◽  
David Jaén-Contreras ◽  
O. Baltazar-Bernal

Objective: To determine the best phorophyte species for the adaptation of the Laelia anceps Lindl orchid. (Orchidaceae) in an anthropized landscape. Design/methodology/approach: A completely randomized experimental design with four treatments (phorophytes) was used: Swietenia macrophylla King., Fraxinus sp., Persea schiedeana Nees. and Tecoma stans. (L.) Juss. ex Kunth), with five repetitions per phorophyte and with three L. anceps orchid plants in each phorophyte. The following variables were measured: day to emergence, root length and thickness, and survival at 28 weeks after tying them in phorophytes. Results: Root emergence of L. anceps occurred in less time in S. macrophylla and in Fraxinus sp. at 52 and 54 days respectively; the longest root length (19.11 cm) and number of roots (32.45) were observed in S. macrophylla. However, the root thickness was greater in Fraxinus sp. (0.28 cm). After 28 weeks of establishing the L. anceps plants; 100% survival was obtained in the phorophytes S. macrophylla and Fraxinus sp., 77% in P. schiedeana and 33% in T. stans. Study limitations/implications: The amount of light received by L. anceps in each phorophyte was not measured. Findings/Conclusions: The best phorophytes for the establishment of L. anceps were S. macrophylla and Fraxinus sp. observed, the best development and strength of the roots and 100% survival at 28 weeks.

Boubacar M. Moussa ◽  
Laouali Abdou ◽  
Salamatou Abdourahamane Illiassou ◽  
Ali Mahamane

In the eastern Niger, vegetable crops such as lettuce are cultivated along the Komadougou Yobé river and near Lake Chad. Insecurity linked to terrorist groups prevents the exploitation of these areas and leads population to explore other lands. This study aims to find out whether sub-arid soils have in some places potentialities that can allow lettuce cultivation. A pedological survey was first carried out in the study area and some physicochemical soil parameters were analyzed. Then, a randomized experimental design with three cultivars (“Blonde de Paris”, “Iceberg Tahoma”, and “Iceberg edem”) and three replicates was carried out on soils which present favorable conditions for vegetable crops. The lettuce fresh mass was determined at harvest. The results show a significant influence of the geomorphological gradient on texture classes, nitrogen contents, pH values, cation exchange capacity and level of exchangeable bases. The lowland soils are more apt for vegetable crops like lettuce. The mean of lettuce fresh mass obtained for the three cultivars is 4.8±0.5 kg.m-². Iceberg Eden records the highest values and seems well adapted to eastern Niger.

Sugey Vásquez Hernández ◽  
Carlos Alberto Cruz Cruz ◽  
Maricela Santiago Santiago ◽  
Jericó Jabín Bello Bello

Objective: To evaluate the effect of different antioxidant agents during in vitro establishment of allspice (Pimenta dioica L. Merrill). Design/methodology/approach: The effect of different antioxidant agents (Methylene blue, L-cysteine, and silver nanoparticles [AnNPs]) added to Murashige and Skoog culture medium at different concentrations were studied during axenic establishment of P. dioica. A completely randomized experimental design was used. All trials were performed in triplicate. The percentage of survival, oxidation, contamination was determined, the phenols content, antioxidant capacity and lipid peroxidation. Results: The highest survival occurred with the addition of L-cysteine. The lowest percentages oxidation were observed in explants treated with L-cysteine. Treatments with 100 and 200 mg L-1 AgNPs had the lowest contamination values. L-cysteine and 50 and 100 mg L-1 AgNPs resulted in an increase in the content of soluble phenols. The highest contents of cell wall-linked phenols were obtained in treatments with 200 mg L-1 methylene blue, L-cysteine, and 200 mg L-1 AgNPs. In this study, all treatments had a reaction of scavenging/reduction mechanisms free radicals. The highest content of malondialdehydes was observed in the control treatment and 200 mg L-1 methylene blue. The highest content of malondialdehydes was observed in the control treatment and 200 mg L-1 methylene blue. Limitations on study/implications: The highest percentage of oxidation was observed in the control treatments, 100 and 200 mg L-1 methylene blue, causing cell death. Findings/conclusions: The addition of L-cysteine to the culture medium is alternative to reduce oxidation during in vitro introduction of P. dioica.

Abraham Monteon-Ojeda ◽  
Agustín Damián-Nava ◽  
Elías Hernández-Castro ◽  
Blas Cruz-Lagunas ◽  
Teolincacihuatl Romero-Rosales ◽  

Objective: To evaluate the insecticidal effectiveness of biorational and conventional products as alternatives to control thrips and their phytotoxic effects in strawberry cultivation. Design / methodology / approach: The research was carried out in strawberry cv. Camino Real during its flowering stage - fruiting established in open ground; A completely randomized experimental design with seven treatments and four replications was used. The treatments evaluated were: T1: neem oil extract, T2: paraffin oil, T3: garlic extract + hot chili pepper + cinnamon, T4: spinosad, T5: imidacloprid + lambda cyhalothrin, T6: bifenthrin, and T7: control. Applications were made weekly and the mortality evaluation was carried out by counting the number of live thrips per flower. With the obtained data, an analysis of variances and a mean comparison test (Tukey, p ≤ 0.05) were performed. Results: Significant differences between treatments could be identified (p ≤ 0.05); imidacloprid + lambda cyhalothrin and bifenthrin caused the highest mortality of thrips with 92 and 93 % efficacy, respectively. Spinosad obtained good results, ranking as the second-best option with 90 % control efficiencies; neem extract stood out as an excellent biorational pest management alternative with 77 % control efficacy in its last evaluation. No phytotoxic effects were observed from any of the treatments on the crop. Limitations on study / implications: It is important to continue the study in the laboratory to obtain the LD50 and LD90 of the management alternatives, as well as an MRL analysis of the molecules used. Findings / conclusions: The proposed protocol evidenced the efficacy of biorational and ecological thrips control treatments in intensive horticultural systems.

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 392-393
Bruno Alexander N Silva ◽  
Simon Eskinazi ◽  
David V Jacob ◽  
Wagner Araújo ◽  
Iara Ataíde ◽  

Abstract Increasing voluntary feed intake of the sow is a major challenge for nutritionists in tropical climate conditions. The present study aimed to evaluate the impact of the dietary supplementation of a feed flavour for sows during lactation on their feeding behavior and kinetics of daily feed intake under tropical conditions. A total of 60 high-prolific mixed parity sows divided into 10 batches of 6 sows each were used, distributed in a completely randomized experimental design among 2 dietary treatments (0 or 500 g/ton of Krave®, Adisseo). The average meal size was 107 g/meal lower in sows fed the control diet when compared with flavour fed sows. Daily feed intake was greater in the flavored diet than in the control (6,417 vs. 5,362 g/d; P &lt; 0.05). The flavor improved ingestion time (58.4 vs. 46.6 min/ d, respectively flavour and control; P &lt; 0.05). Sows receiving flavor showed a higher nocturnal (704 vs. 583 g/meal) and diurnal (678 vs. 582 g/meal) feed intake. Sows also showed a higher voluntary intake between 00:00 and 10:00 am, which was equivalent to 83% of the total daily feed intake. From a comparison of hourly feed intakes or variations from hour to hour (during 24 h), the nycthemeral pattern of feed intake peaked twice daily for both dietary treatments. However, the size of the peak was greater (P &lt; 0.05) for flavour fed sows when compared with the control at 0400 and 1900 h (Figure 1a). Diets also influenced on kinetics of daily feed intake during the lactation period.Feed intake was higher for the flavour fed sows from d 3 to 8 and from d 10 to 24 (Figure 1b; P &lt; 0.05).In conclusion, the strategic use of a feed flavour to manipulate the sensorial properties of feed is a viable strategy to increase the sows’ voluntary feed intake.

2021 ◽  
Vol 51 (4) ◽  
pp. 830
Norma Barbado ◽  
Marcelo Bevilacqua Remor ◽  
Patrícia Pereira Gomes ◽  
Fernanda Rúbio ◽  
Rodrigo De Oliveira ◽  

Schinus terebinthifolius is a pioneer species of the Atlantic Forest. Thus, this study aims to evaluate the germination process of S. terebinthifolius seeds collected in four sites with different altitudes (São Francisco do Sul/SC, 2.53 m; Foz do Iguaçu/PR, 176.67 m; Maringá/PR, 458.00 m; Guarapuava/PR, 1,048.70 m) and their initial development under four luminosity levels. For the germination test, we used the completely randomized experimental design with 12 repetitions with 50 seeds per treatment. The seedlings were subjected to the luminosity levels of 50, 60, 70, and 100%. A triple factorial scheme, with four levels in each factor (43), was used to evaluate the seed collection site, luminosity, and seedling’s development period. Principal components analysis was applied to the correlation matrix in the set of response variables emerging from the treatments. Seeds collected in São Francisco do Sul/SC presented higher vigor, and better germination speed index (GSI), development of the primary root and aerial part length. However, they also presented the worst result for the vegetative growth of seedlings subjected to a luminosity of 50%. Seeds collected in Maringá/PR presented a lower germination percentage and GSI. Still, they obtained the better results for vegetative development of seedlings subjected to a luminosity of 70%. This study confirmed that S. terebinthifolius seedlings, when exposed to luminosity higher than 60%, present better adaptation and development. Nonetheless, further studies about altitude and management are required to foster the recovery of degraded areas. 

2021 ◽  
Vol 12 ◽  
Sophie P. Barnes ◽  
Rebecca Bailey ◽  
Stephanie M. Jones

This paper reports results from an impact study of Brain Games (BGs), a classroom-based intervention designed to build preschool and school-aged children’s executive functions (EFs) and related self-regulation skills. The study employed a classroom-randomized, experimental design with 626 students in 36 pre-K through fourth grade classrooms in charter schools in a mid-sized urban district. In one set of models with child covariates, children in intervention classrooms showed marginal positive impacts on regulation-related behaviors, attention control and impulsivity, and negative effects on global EF and marginal increases in discipline problems. A second set of models with a smaller sample and both child and classroom covariates included indicate positive impacts of BGs on global EFs, prosocial behavior, and attention control and impulsivity. There were no significant impacts on the teacher–student relationship as reported by the teacher or on direct assessments of inhibitory control, short term and working memory, or another measure of global EF in either set of models. These promising findings offer a signal that implementation of targeted, easy to implement intervention approaches in classroom contexts can influence children’s regulation-related and prosocial outcomes, but this signal should be investigated further with larger and more tightly controlled designs.

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