Effect Of Sequential Application Research Articles

Effect of sequential application of herbicides on productivity and profitability of transplanted rice

Effect of sequential application of herbicides on productivity and profitability of transplanted rice

English

English

English

English

Effects of Sequential Applications of Bassa 50EC (Fenobucarb) and Vitashield 40EC (Chlorpyrifos ethyl) on Acetylcholinesterase Activity in Climbing Perch (Anabas testudineus) Cultured in Rice Fields in the Mekong Delta, Vietnam.

This study assesses the effects of sequential applications of the insecticides Bassa 50EC (fenobucarb-F) and Vitashield 40EC (chlorpyrifos ethyl-CPF), sprayed at concentrations used by rice farmers in the Mekong Delta, on the brain acetylcholinesterase (AChE) in climbing perch fingerlings. After spraying the pesticides on the rice fields, the water concentrations of both insecticides decreased below the detection levels within 3days. The sequential applications caused significant inhibition on the brain AChE activity in the exposed fish. The inhibition by F was quicker, but less prolonged, than for CPF. The inhibition levels caused by the sequential applications were lower than those caused by only CPF and by a mixture of CPF and F. The results indicate that sequential applications of pesticides could have a negative impact on aquatic organisms and fish yields, with implication for the aquatic biodiversity, local people's livelihood and the aquaculture industry in the Mekong Delta.

Effect of sequential application of herbicides on microbial activities and yield of maize

Effect of sequential application of herbicides on microbial activities and yield of maize

Effect of sequential application of metribuzin on selectivity and weed control in soybean

Post-emergence treatments are often the keys to efficient weed control, and could be a substitute or supplementary to pre-emergence treatment. Accordingly, this study was designed to test the selectivity and efficacy of sequential (pre- + post-emergence) applications of metribuzin on weeds in soybean, and to optimize the dose, volume rate and time of application. We observed that sequential metribuzin treatments were more toxic to soil micro-organisms and caused greater inhibition in photosynthesis, acetylene reduction activity and nodulation of soybean compared to only pre-emergence applications of metribuzin or pendimethalin. The negative effects, however, were mitigated by increased activities of superoxide dismutase and ascorbate peroxidase in soybean. The sequential applications left negligible residues at harvest. A sequential application of metribuzin 0.25 kg ha−1 2 days after sowing and 0.1 kg ha−1 20 days after sowing with 200 Lha−1 of water gave a higher seed yield. This ensured the possibility of sequential application of metribuzin with an optimized dose, volume rate and time of application.

Effect of sequential applications of topical tacrolimus and topical corticosteroids in the treatment of pediatric atopic dermatitis: An open-label pilot study

Effect of sequential applications of topical tacrolimus and topical corticosteroids in the treatment of pediatric atopic dermatitis: An open-label pilot study

Efeito da interação do nicosulfuron e chlorpyrifos sobre o banco de sementes e os atributos microbianos do solo

Considerando o período de competição de plantas daninhas e a incidência da lagarta-do-cartucho na cultura do milho, há necessidade de aplicação, em curto intervalo de tempo, de herbicidas e de inseticidas, principalmente o nicosulfuron e o chlorpyrifos. O objetivo deste estudo foi avaliar o efeito da aplicação sequencial do nicosulfuron e do chlorpyrifos sobre a emergência de plântulas do banco de sementes, a taxa de desprendimento de CO2 (respiração basal) e o C da biomassa microbiana (CBM) do solo. Foi realizada aplicação sequencial, em solo, do nicosulfuron (doses de 0 a 64 g ha-1) associado ou não ao chlorpyrifos (0 e 240 g ha-1). Aos 20, 40 e 60 dias após a aplicação (DAA) dos produtos, todas as plântulas emergidas do banco de sementes foram identificadas em nível de espécie, sendo estimadas a frequência, densidade e abundância, além do índice de valor de importância (IVI). Aos 60 DAA, determinou-se também a taxa de desprendimento de CO2, o CBM e o quociente metabólico (qCO2), por meio da relação entre o CO2 acumulado e o CBM total do solo. A aplicação alterou severamente a massa de plântulas secas e o número de espécies nas doses superiores a 20 g ha-1 do nicosulfuron. Na presença do herbicida, as espécies com maior IVI foram Boehavia diffusa e Commelina benghalensis. Quanto aos bioindicadores do solo, foi observado decréscimo na taxa da respiração basal do solo com o aumento da dose aplicada do nicosulfuron associado ao chlorpyrifos, sem efeito na ausência do inseticida. Houve decréscimo linear no CBM em todos os casos, independentemente da aplicação do chlorpyrifos; entretanto, observou-se uma taxa de decréscimo 4,5 vezes maior para o solo que recebeu esse inseticida em conjunto com o nicosulfuron. A avaliação do qCO2 confirmou o efeito negativo da aplicação do inseticida e do herbicida. Conclui-se que a aplicação de chlorpyrifos + nicosulfuron promove impacto negativo sobre o banco de sementes e sobre a atividade microbiana do solo.