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Objective: To verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish., Study Design: Clinical study, randomized, parallel, multi-arm with control group in target species., Animals: A total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used., Methods: Silver catfish and grass carp were exposed to different concentrations of citral, 15-675 and 15-600 μL L -1 , respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 μL L -1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 μL L -1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment., Results: Citral only induced sedation from 15, 25 and 40 μLL -1 in both species. Anesthesia without mortality was induced in silver catfish at 50-600 μL L -1 and grass carp at 75-450 μL L -1 . At 675 and 600 μL L -1 , mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments., Conclusions and Clinical Relevance: Citral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish., (Copyright © 2021. Published by Elsevier Ltd.)

The aim of this study was to analyze the effects of Trichoderma asperellum on germination indexes and seedling parameters of lettuce cultivars. The trial was arranged in a completely randomized design with three cultivars (Cerbiata, Crespa Grand Rapids, and Mimosa), and two seed-treatment products (quality and organic) containing strain URM 5911 of Trichoderma asperellum plus a control group (untreated), with four repetitions. After seven days, six seedling characters were measured (shoot length, radicle length, total length, shoot diameter, radicle diameter, and seedling dry matter) and eight germination indexes were calculated (germination, first count, mean germination time, germination speed index, coefficient of velocity of germination, mean germination rate, Timson's germination index, and germination rate index). In general, regarding the germination indexes, the effect of the genotype factor predominated over the Trichoderma factor. The seedling characters showed significance for genotype × Trichoderma interaction for shoot length, shoot diameter, radicle diameter, and seedling dry matter. Such results demonstrate that the effects of Trichoderma asperellum on lettuce seedlings variate according to the cultivar used., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.