With the advent of precision agriculture, it was possible to integrate several technologies to develop the variable rate application (VRA). The use of VRA allows savings in the use of herbicides, better weed control, lower environmental impact and, indirectly, increased crop productivity. There are VRA techniques based on maps and sensors for herbicide application in preemergence (PRE) and postemergence (POST). The adoption of the type of system will depend on the investment capacity of the producer, skilled workforce available, and the modality of application. Although it still has some limitations, VRA has been widespread and has been occupying more and more space in chemical management, the tendency in the medium- and long term is that there is a gradual replacement of the conventional method of application. Given the benefits provided by VRA along with the engagement of companies and researchers, there will be constant evolution and improvement of this technology, cheapening the costs of implementation and providing its adoption by an increasing number of producers. Thus, the objective of this chapter was to address an overview of the use of herbicides in VRA for weed management in PRE and POST.
Spray nozzles can be considered the most important items of sprayers, and the ideal nozzle-pressure combination plays a major role in the effectiveness of pest control in the field. Spray nozzle manufacturers often develop, and make new alternatives available on the market; however, studies are always important to verify the behavior of these new technologies concerning the spectrum of the droplets produced. Therefore, the present study aimed to evaluate the spectrum of droplets generated by four spray nozzles (FC3D 100-02; VP 110-02; TR 110-02 and TT 110-02) under different working pressures (138, 207, 276, 345, and 414 kPa). For this, a factorial scheme in a completely randomized design with four replications was used. The parameters evaluated were volumetric median diameter (VMD), relative amplitude (Span), and the percentage of droplets with a diameter smaller than 100 μm (<100 μm). The spray nozzles models and the working pressure had a direct effect on the droplet size. Furthermore, there were no significant differences between the TR 110-02 and VP 110-02 models for the percentage of spray volume containing droplets <100 μm neither for the VMD. Lastly, the increase of pressure resulted in an increasing linear effect on the Span index for the FC3D 100-02 nozzle.
IntroduçãoBauhinia rufa (Fabaceae) é uma planta conhecida popularmente como pata de vaca, sendo uma espécie lenhosa que pode apresentar hábito arbustivo e é comumente encontrada nas bordas das matas, apresentando distribuição que compreende boa parte do território brasileiro (Vaz e Tozzi, 2003). Esta espécie possui uso como planta medicinal e produz ésteres que proporcionam efeito negativo na sobrevivência de afídeos pragas em culturas (Bichuette et al., 1998). No entanto, a maior importância de uso se dá como componente de recuperação de áreas degradadas (RAD).Sementes de B. rufa podem ser misturadas a outras sementes e lançadas em áreas a serem recuperadas e dessa maneira revegetar áreas degradadas ou em processo de degradação. No entanto é frequente na RAD com B. rufa a dormência das sementes, acarretando, falhas de cobertura e desuniformidade de emergência. A falta de informações das fases de embebição de sementes e de dados biométricos da mesma também provocam dúvidas quanto a época de semeadura em relação a fase de necessidade hídrica e aos coeficientes biométricos das sementes. Devido a carência de informações das sementes de B. rufa e a importância de uso e aplicação, objetivou-se avaliar a biometria, embebição e superação de dormência de sementes de Bauhinia rufa. Fundamentação TeóricaA influência do tamanho das sementes sobre a qualidade fisiológica tem sido pesquisada com certa intensidade em várias espécies (Alves et al., 2005). A caracterização física de sementes
Herbicides applied in PRE-emergence enables sustainable weed control. The objective of this study was to evaluate the control of gallant soldier (Galinsoga parviflora) with the residual herbicides oxyfluorfen, flumioxazin, and linuron in soils cultivated with garlic from two regions of Brazil: Rio Paranaíba-MG (Oxisol) and Curitibanos-SC (Ultisol). The efficiency of the herbicides was evaluated at the following doses: oxyfluorfen (0, 3, 6, 12, 24, 48, 96, 192, 384, and 768 g a.i. ha−1), flumioxazin (0, 2, 4, 6, 8, 15, 30, 40, 60, and 120 g a.i. ha−1), and linuron (0, 30, 40, 50, 100, 200, 400, 800, 1600, and 2430 g a.i. ha−1). The degree of damage on the 7th, 14th, and 21st day after emergence (DAE) and dry matter on the 21st day after emergence (DAE) were determined to evaluate the control (C80) and the growth reduction (GR80) of 80% of the plant, respectively, compared to the treatment without herbicide. Three herbicides were effective at the control of G. parviflora, with the C80 at 21 DAE on Ultisol being 81.82, 4.59, and 141.26 g a.i. ha−1, and a GR80 of 61, 8.3, and 151.3 g a.i. ha−1 for oxyfluorfen, flumioxazin, and linuron, respectively. On the other hand, on Oxisol (lower clay content and soil organic matter), the doses were lower, with the C80 at 21 DAE at 20.85, 3.50, and 118 g a.i. ha−1, and a GR80 of 54, 4.03, and 101.23 g a.i. ha−1, respectively. This weed showed higher control under flumioxazin compared to the other herbicides in both soils. The use of low doses of residual herbicides contributes to sustainable weed control in garlic growing in the field.
A utilização de herbicidas aplicados em pré-emergência (PRE), promove controle precoce e eficiente das plantas daninhas e com efeito residual. A eficiência desses herbicidas é dependente da sua biodisponibilidade (BD) na solução do solo, que ainda é pouco estudada. As recomendações de doses de herbicidas em PRE pouco consideram a variabilidade espacial nas características físico-químicas do solo que determinam a BD. O objetivo deste estudo foi realizar o mapeamento da variabilidade espacial da sorção e dessorção e eficiência agronômica do indaziflam e metribuzin em solos para o manejo de precisão de plantas daninhas. Um total de 55 amostras de solo georreferenciadas foram coletadas em Viçosa - MG para análises físico- químicas do solo e sorção e dessorção do indaziflam e metribuzin por cromatografia líquida de alta eficiência com o método batch equilibrium. A eficiência agronômica dos herbicidas no controle de Amaranthus hybridus e Eleusine indica foi avaliada para determinar a dose do herbicida que causa 80% de injúria (C 80 ) e 80% de redução no acúmulo de biomassa (GR 80 ). O indaziflam apresentou K d(s) de 6,90 a 40,49 L Kg -1 , porcentagem sorvida (S%) de 61,04 a 86,61%, porcentagem dessorvida (D%) de 8,40 a 33,10% e BD% de 26 – 55,7%. O metribuzin apresentou K d(s) de 1,06 a 4,29 L Kg -1 , S% de 22,80 a 33,90%, D% de 17,20 a 22,00% e BD% de 79,4 – 96,7%. A matéria orgânica (MO) teve alta correlação com a BD% do indaziflam (r = -0,81) e metribuzin (r = -0,71). As concentrações na solução do solo (Ce) de 1,91 e 1,94 g i.a. ha -1 do indaziflam controlaram 80% do A. hybridus e E. indica, respectivamente. As doses de 55,16 e 111,16 g i.a. ha -1 de metribuzin controlaram 80% do A. hybridus e E. indica, respectivamente. As doses de indaziflam para o manejo de precisão de A. hybridus variaram de 4,17 a 6,97 g i.a. ha -1 , e de 4,24 a 7,08 g i.a. ha -1 para E. indica, correspondendo a uma variação de 67,14 e 66,98%, respectivamente. As doses do metribuzin para o controle do A. hybridus variaram de 57,10 a 66,60 g i.a. ha -1 e 94,30 a 110,10 g i.a. ha -1 para E. indica, correspondendo a 16,63 e 16,75% de variação, respectivamente. As recomendações de doses variadas proporcionaram reduções de 17,56% na aplicação total de indaziflam e 9,80% de metribuzin em relação a maior dose recomendada no estudo. O estudo conjunto das características físico- químicas do solo que interferem na BD% dos herbicidas e a eficiência agronômica dos herbicidas possibilitaram recomendar doses de herbicidas com alta acurácia para o manejo de precisão de plantas daninhas em PRE. Palavras-chave: Taxa variada. Agricultura de precisão. Pré-emergência.
Dinizia excelsa is one of the largest trees in the Amazon rainforest, with significant economic potential for the recovery of degraded areas. It is a key species for biodiversity and increased forest biomass. However, studies related to seedling production of this species are still scarce. In this study, we evaluated the production and quality of D. excelsa seedlings in response to the application of controlled-release fertilizer doses. The experimental design was completely randomized, applying different doses of Osmocote® (T1=0; T2=4.1; T3=8.2; and T4=12.3 g.dm-³) with four replicates, using vermiculite and coconut fiber (1:1 v/v) as the substrate. We assessed the number of leaves and leaflets, shoot and root length, stem diameter, seedling height, shoot-to-stem diameter ratio, leaf area, dry mass of shoot, root, and total biomass. The data were subjected to analysis of variance and regression analysis. The seedlings responded positively to the use of Osmocote®, and starting from the 4.1 g.dm-³ dose, biomass accumulation showed better results, making it a recommended practice that allows cost savings in seedling production of this species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.