Abstract:As plantas infestadas são responsáveis por perdas significativas na produção do algodão a nível mundial, cujo controle é difícil e oneroso. Com o objetivo de se estimar custos de produção e analisar economicamente a eficiência da plasticultura e de métodos de controle de ervas daninhas na cultura do algodoeiro herbáceo irrigado e em sequeiro, utilizaram-se dados obtidos de ensaios conduzidos nos municípios de Barbalha e Missão Velha, no Cariri Cearense, determinando-se o custo de produção, a receita líquida, o… Show more
“…Faria et al (2011), studying the influence of different water management and fertilizer levels, also found a positive irrigation effect on the Jatropha plant canopy diameter, showing the high influence of water management in the plant development. The fast increase in plant height and canopy diameter over time was explained due the fast Jatropha plant development, in which it can reach easily 5 m height in adequate soil and climate conditions (Openshow, 2000;Arruda et al, 2004). AGR H were higher for more drastic pruning (P2), observed by the statistical differences at 60 and 90 DAP in comparison to P1 and P3.…”
Section: Effect Of Treatments On Plant Growth Parametersmentioning
Jatropha is an oilseed culture that has been highlighted due some specific agronomic aspects. This plant produces high oil quantities in its seeds that is used for biodiesel production. One of the major challenges regarding to the Jatropha cultivation is the lack of information on many management techniques, especially the irrigation and pruning management in adult plants in southeastern Brazil. The objective of this study was to study the combined effect of irrigation history and different pruning on Jatropha plant growth and yield. The experiment was conducted during the 4 th year of Jatropha growing season at University of Sao Paulo experimental area in Piracicaba, Brazil. The experiment was arranged in randomized block with four replications and treatments were considered the pruning type: No pruning (P1), pruning at 1.5 m high and 2 m canopy diameter (P2), pruning at 2 m high and 2 m canopy diameter (P3). In addition, two water conditions were also evaluated: Irrigated (I) and rainfed conditions (R). Plant growth (height and canopy diameter) and leaf area index (LAI) were evaluated monthly and productive variables were determined at the end of the experiment. Irrigation history influenced canopy diameter, absolute growth rates for plant height and canopy diameter, the relative growth rate for canopy diameter, and all productive variables. Pruning provided differences in all growth variables, where P2 presented the highest average on plant growth rates. The plants under irrigation history conditions showed the highest yield.
“…Faria et al (2011), studying the influence of different water management and fertilizer levels, also found a positive irrigation effect on the Jatropha plant canopy diameter, showing the high influence of water management in the plant development. The fast increase in plant height and canopy diameter over time was explained due the fast Jatropha plant development, in which it can reach easily 5 m height in adequate soil and climate conditions (Openshow, 2000;Arruda et al, 2004). AGR H were higher for more drastic pruning (P2), observed by the statistical differences at 60 and 90 DAP in comparison to P1 and P3.…”
Section: Effect Of Treatments On Plant Growth Parametersmentioning
Jatropha is an oilseed culture that has been highlighted due some specific agronomic aspects. This plant produces high oil quantities in its seeds that is used for biodiesel production. One of the major challenges regarding to the Jatropha cultivation is the lack of information on many management techniques, especially the irrigation and pruning management in adult plants in southeastern Brazil. The objective of this study was to study the combined effect of irrigation history and different pruning on Jatropha plant growth and yield. The experiment was conducted during the 4 th year of Jatropha growing season at University of Sao Paulo experimental area in Piracicaba, Brazil. The experiment was arranged in randomized block with four replications and treatments were considered the pruning type: No pruning (P1), pruning at 1.5 m high and 2 m canopy diameter (P2), pruning at 2 m high and 2 m canopy diameter (P3). In addition, two water conditions were also evaluated: Irrigated (I) and rainfed conditions (R). Plant growth (height and canopy diameter) and leaf area index (LAI) were evaluated monthly and productive variables were determined at the end of the experiment. Irrigation history influenced canopy diameter, absolute growth rates for plant height and canopy diameter, the relative growth rate for canopy diameter, and all productive variables. Pruning provided differences in all growth variables, where P2 presented the highest average on plant growth rates. The plants under irrigation history conditions showed the highest yield.
“…Among the weeds control techniques, the use of chemicals has been the most usual solution adopted by farmers because it is less labor intensive, has a high control efficiency, and is more cost-effective when compared to the other methods (Arruda et al, 2005). In bean crops, weeds control can be achieved with post-emergence applications of the commercial mixture of fluazifop-p-butyl and fomesafen herbicides (Manabe et al, 2014).…”
O conhecimento das alterações na comunidade infestante provocado pelo manejo de plantas daninhas é importante para definição de estratégias eficientes para o controle destas. Realizou-se um experimento de campo para avaliar os efeitos do uso de herbicidas em diferentes alturas de barra na dinâmica de plantas daninhas e produtividade do feijoeiro. Adotou-se arranjo fatorial em esquema 3x4+1, constituído pela combinação de três herbicidas (fomesafen, fluazifop-p-butil e sua mistura) e quatro alturas de barras do pulverizador (0,20; 0,30; 0,40 e 0,50 m) e mais a testemunha sem capina. Aos 30 dias após aplicação (DAA) determinou-se os seguintes índices fitossociológicos: frequência relativa, densidade relativa, dominância relativa, índice de valor de importância e índice de similaridade. Aos 60 DAA foi determinada a produtividade. Antes da instalação do experimento foram identificadas 22 espécies em toda área experimental. As espécies Alternanthera tenella, Chelidonium majus, Digitaria horizontalis e Bidens pilosa predominaram na área cultivada em que não houve controle. A redução da altura de barras na aplicação do fomesafen reduziu a importância das espécies eudicotiledôneas. Nas parcelas com aplicação de fomesafen + fluazifop-p-butil o número de infestantes eudicotiledôneas foi superior às demais, com predominância de A. tenella e B. pilosa. No geral, o índice de similaridade entre os diferentes herbicidas e as diferentes alturas de barra foi baixo, o que indica que os tratamentos aplicados resultam em diferentes populações de plantas daninhas. O feijoeiro reduz a diversidade de plantas daninhas e a aplicação de herbicidas altera a infestação destas com consequência no ganho em produtividade.
“…Adicionalmente, Arruda et al (2005) mencionam que o controle difícil dessa espécie resulta em aumentos significativos no custo de produção do algodoeiro.…”
R E S U M OObjetivou-se, neste trabalho, avaliar a seletividade do herbicida halosulfuron-methyl para a cultura do algodoeiro quando aplicado na dessecação antes da semeadura. Dois experimentos foram conduzidos em condições de casade-vegetação em delineamento inteiramente casualizado com quatro repetições. Os tratamentos corresponderam a quatro períodos entre a aplicação do herbicida e a semeadura (0, 7, 14 e 21 dias) e uma testemunha sem aplicação. Os solos utilizados como substrato em cada experimento foram classificados como arenoso e francoargilo-arenoso. As avaliações realizadas foram: altura de plantas aos 7, 14, 21 e 28 dias após a emergência (DAE); diâmetro do caule, área foliar, volume de raízes, massa seca de parte aérea e raízes aos 28 DAE. Foi possível concluir que o halosulfuron-methyl aplicado até 14 dias antes da semeadura não é seletivo ao algodoeiro.
Selectivity of halosulfuron-methyl applied in desiccation before seeding of cotton crop
A B S T R A C TThe aim of this study was to evaluate the selectivity of the herbicide halosulfuron-methyl in cotton when applied in desiccation before seeding. Two trials were conducted under green-house conditions in a completely randomized design with four replications. The treatments corresponded to four periods between herbicide application and seeding (0, 7, 14 and 21 days) and a control without application. The soils used as substrate in each experiment were classified as sandy and sandy clay loam. The evaluations made were: plant height at 7, 14, 21 and 28 days after emergence (DAE); stem diameter, leaf area, root volume, dry mass of aerial parts and roots at 28 DAE. It was possible to conclude that halosulfuron-methyl applied up to 14 days before sowing was not selective to cotton.Seletividade do halosulfuron-methyl aplicado na dessecação antes da semeadura da cultura do algodoeiro
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