Search

The objective of this study was to evaluate the effects of soil cover with sugarcane residue on weed emergence of four weeds from the genus Brachiaria. The study was conducted in an area whose soil was classified as Red Nitosol. Seven different amounts of sugarcane residue (0, 3, 6, 9, 12, 15 and 18 ton ha-1) were used as soil cover. The residue of variety SP832847 was used upon four weed species: Brachiaria decumbens, B. brizantha, B. ruziziensis, and, B. humidicola. The experimental design was a randomized block with four replications. The weeds were sown 1 cm deep and covered by the residue. The seeding rate in use was 1,200 plants m-2. The study was comprised of two phases: the first phase was an evaluation of plant emergence (more than 1 cm for shoots) at 9, 12, 19, 34 and 43 days after sowing (DAS), and in the second phase, plant emergence was evaluated after removal of the straw residue at 89, 130, 175, 196, 217 and 234 DAS. The amount of sugarcane residue used as soil cover influenced the emergence pattern of Brachiaria spp. Minor germination was noticed after residue removal. Amounts greater than 9 ton ha-1 decreased the total number of seedlings in all species, except for B. ruziziensis, whose emergence decreased at 12 ton ha-1. RESUMO O objetivo deste trabalho foi avaliar os efeitos da cobertura do solo com palha de cana-deaçúcar sobre a emergência de plantas daninhas do gênero Brachiaria spp. O estudo foi conduzido em uma área pertencente à Fazenda Experimental da UNESP, campus Botucatu/SP, em um solo classificado como Nitossolo Vermelho de textura argilosa. Foram avaliadas sete diferentes quantidades de palha de cana-de-açúcar (0, 3, 6, 9, 12, 15 e 18 t ha-1) utilizadas como coberturas do solo. Utilizou-se a palha da variedade SP832847 sobre quatro espécies de plantas daninhas: Brachiaria decumbens, B. brizantha, B. ruziziensis e B. humidicola. O delineamento experimental utilizado foi de blocos casualizados com quatro repetições. As plantas daninhas foram semeadas a 1 cm de profundidade e posteriormente cobertas pela palha. A taxa de semeadura utilizada foi 1.200 plantas m-2. O estudo foi compreendido por duas fases distintas: na primeira, foram avaliadas as plantas emersas (mais de 1 cm de parte aérea) aos 9, 12, 19, 34 e 43 dias após a semeadura (DAS) e, na segunda, a emergência das plantas após a remoção da palha aos 89, 130, 175, 196, 217 e 234 DAS. A quantidade de palha de cana-de-açúcar usada como cobertura do solo influenciou a dinâmica de germinação das diferentes espécies de Brachiaria. Após a remoção do palhiço de cana-de-açúcar utilizado como cobertura do solo, houve pouca germinação dessas espécies. Quantidades superiores a 9 t ha-1 proporcionaram redução do número total de plântulas em todas as espécies, com exceção de B. ruziziensis que apresentou redução a partir de 12 t ha-1.

The action of herbicides on weeds that develop under water deficit can be compromised, because the routes of penetration of hydrophilic herbicides are reduced due to the lower hydration of the cuticle in these plants. Moreover, hydrophobic compounds found in the epicuticular wax coating of plants under water stress, hinder the penetration of hydrophilic compounds. This study evaluated the control efficiency of glyphosate on guineagrass plants when submitted to different water deficits. The study was conducted in a greenhouse, and treatments were composed of guineagrass plants submitted to three soil water conditions [low water deficit (13%), intermediate water deficit (10%) and high water restriction (8%)], three doses of glyphosate (0.0, 270.0 and 540.0 g ha-1) and two phenological stages of plant development (4-6 leaves and 1-3 tillers). The water management started when plants presented two developed leaves. Visual evaluations were performed 7, 14, 21 and 35 days after the application of the herbicide; the morpho-physiological parameters of the specific leaf area, stomatal conductance and the difference between the environment temperature and the leaf temperature on the day of the herbicide application were also analyzed at the end of the study, as well as the dry matter of shoot and root. With the increase of the water restriction, there was a decrease in the analyzed morpho-physiological parameters, as well as in the dry matter accumulation of the shoot and roots of the studied plants. Plant control was more efficient when a 540 g ha-1 dose of glyphosate was applied, and when they were controlled at their vegetative stage of 1-3 tiller, and with a water management of 13%. It is possible to state that guineagrass under water restriction have less control efficacy when treated with glyphosate. RESUMO: A ação de herbicidas sobre plantas daninhas que se desenvolvem sob déficit hídrico pode ser comprometida, pois as rotas de penetração de herbicidas hidrofílicos são reduzidas em razão da menor hidratação da cutícula nessas plantas. Além disso, compostos hidrofóbicos presentes na camada de cera epicuticular em plantas estressadas hidricamente dificultam sobremaneira a penetração de compostos hidrofílicos. Avaliou-se neste estudo a eficiência de controle do herbicida glyphosate em plantas de capim-colonião quando submetidas a distintos déficits hídricos. O estudo foi conduzido em casa de vegetação, sendo os tratamentos compostos por plantas de capim-colonião submetidas a três condições hídricas do solo [baixo déficit hídrico (13%), déficit hídrico intermediário (10%) e alta restrição hídrica (8%)], três doses do herbicida glyphosate (0,0, 270,0 e 540,0 g e.a. ha-1) e dois estádios fenológicos de desenvolvimento da planta (4-6 folhas e 1-3 perfilhos). O manejo hídrico teve início quando as plantas apresentaram duas folhas desenvolvidas. Foram realizadas avaliações visuais de controle aos 7, 14, 21 e 35 dias após a aplicação do herbicida; analisaram-se ainda os parâmetros morfofisiológicos área foliar específica, condutância estomática e a diferença de temperatura do ambiente com a temperatura foliar no dia da aplicação do herbicida, bem como a matéria seca da parte aérea e da raiz ao final do estudo. Com o aumento da restrição hídrica, houve decréscimo nos parâmetros morfofisiológicos analisados, bem como no acúmulo de matéria seca da parte aérea e das raízes das plantas estudadas. O controle das plantas foi mais eficiente quando ocorreu a aplicação da dose de 540 g ha-1 de glyphosate, quando elas foram controladas no estádio vegetativo de 1-3 perfilhos, e no manejo hídrico de 13%. Pode-se afirmar que plantas de capim-colonião sob restrição hídrica têm menor eficácia de controle quando tratadas com glyphosate.

This study has aimed to evaluate the effect of prohexadione-calcium as a plant growth regulator on growth and quality of Japanese lawn grass, Broadleaf carpet grass and Bermudagrass. The treatments and doses of the prohexadione-calcium tested with two three reapplications were 27.5, 55.0, 110.0, 165.0 and 165.0 g a.i. ha-1, and a control without application of a growth regulator. Visual injury evaluations were performed using a scale of scores and plant height and chipping dry matter were determined. We have evaluated the total thickness of the sod grass, root length and dry matter of this material at the end of the experimental period. The study was arranged in a completely randomized design with four replications. The results were submitted to analysis of variance by F-test and the averages of the treatments were compared by t test at 5% probability. The prohexadione-calcium plant growth regulator was visually selective and reduced shoot growth of the three species of grass and can thus be used in the management of lawns in gardens and sports areas. As for the production of sod grass, the prohexadione-calcium can be recommended for Japanese lawn grass and Broadleaf sod grass, especially doses 165.0+165.0 and 55.0+55.0+55.0 respectively, because they have provided a better quality sod grass. For Bermudagrass, the effect of the treatments was harmful for the quality of sod grass and is not recommended for production purposes. RESUMO: O presente trabalho teve por objetivo avaliar o uso do prohexadione-cálcio como regulador vegetal sobre o desenvolvimento e a qualidade de tapetes de gramas das espécies Esmeralda, São Carlos e Bermuda. Os tratamentos e doses de prohexadione-cálcio testados, com duas e três reaplicações, foram: 27,5, 55,0, 110,0, 165,0 e 165,0 g i.a. ha-1, além de uma testemunha sem aplicação do regulador de crescimento. Foram realizadas avaliações visuais de fitotoxicidade, altura das plantas e determinação da massa seca das aparas. Ao final do estudo, avaliou-se a espessura total do tapete, o comprimento de raiz e a massa seca deste material. O estudo foi instalado em um delineamento experimental inteiramente casualizado com quatro repetições. Os resultados foram submetidos à análise de variância pelo teste F, e as médias dos tratamentos, comparadas pelo teste t a 5% de probabilidade. O regulador vegetal prohexadione-cálcio foi visualmente seletivo e reduziu o crescimento da parte aérea das três espécies de grama, podendo ser utilizado no manejo de gramados em jardins e áreas esportivas. Quanto à produção de tapetes, o prohexadione-Ca pode ser recomendado para as gramas Esmeralda e São Carlos, com destaque para as doses de 165,0+165,0 e 55,0+55,0+55,0, respectivamente, pois proporcionaram uma melhor qualidade de tapete. Para a grama Bermuda, o efeito dos tratamentos foi prejudicial à qualidade dos tapetes, não sendo recomendado para fins de produção.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:27:32Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:48:04Z : No. of bitstreams: 1 2-s2.0-84878337615.pdf: 699213 bytes, checksum: 23dd1f594811d33823284959bef01d36 (MD5) Made available in DSpace on 2014-05-27T11:27:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-01 The drift is intimately linked to inappropriate use of pesticides and an important factor for reducing it, is the correct selection of spray nozzles and adjuvants. The objective of this work was to evaluate the drift potential in wind tunnel with different spray nozzles and different concentrations of adjuvants. The experiment was composed by six spray solutions (vegetable oil (in three concentrations), mineral oil, surfactant and reducing drift), which were applied with two nozzles, one pre-orifice flat fan (DG 8003 VS) and other with air induction (AI 8003 VS), totaling 12 treatments, with three repetitions. The equipment used was a wind tunnel, where the drift collections were made at different points. The treatments averages were compared using Confidence Interval at 5% probability. The analysis of the percentage of drift showed that the treatments had different behaviors. The nonylphenol ethoxylate adjuvant presented the highest drift when applied with the nozzle of pre-orifice and the lowest drift when applied with the air induction. The behavior of these nozzles when the oil-based adjuvant was used showed apposite results to those obtained for the surfactant. For the DG nozzles the lowest percentage of drift, at all analyzed distances, was observed to the treatment with vegetable oil (1.0%) and with the AI nozzles the lower drift was found for the treatment with nonylphenol ethoxylate (0.0625%), for the four distances in the collection. The result showed that both the spray nozzles and adjuvants alter directly the drift potential. There was no proportionately between the concentration of the oil-based adjuvant and the drift percentage. Universidade Estadual Paulista UNESP Campus de Botucatu, Botucatu, SP Dept. de Engenharia Rural Faculdade de Ciências Agronômicas UNESP, Botucatu, SP UNESP, Botucatu, SP Universidade Estadual Paulista UNESP Campus de Botucatu, Botucatu, SP Dept. de Engenharia Rural Faculdade de Ciências Agronômicas UNESP, Botucatu, SP UNESP, Botucatu, SP