Selection of bioindicator species for the herbicide indaziflam

O herbicida indaziflam apresenta atividade residual no solo e pode se tornar problema para os cultivos agrícolas, pela possibilidade de carryover em culturas sucessoras. Assim, objetivou-se selecionar potenciais espécies bioindicadoras para presença de resíduos do indaziflam no solo. Foram realizados dois experimentos em casa de vegetação, utilizando vasos de polietileno de 0,00025 m3, ambos distribuídos no delineamento em blocos ao acaso com quatro repetições. No primeiro experimento foram utilizadas onze espécies com potencial uso como bioindicadoras: arroz, aveia, beterraba, capim-braquiária, feijão, girassol, milho, pepino, soja, tomate e trigo submetidas à aplicação de sete doses de indaziflam (0; 6,25; 12,5; 25; 50; 75 e 100 g i.a. ha-1). em pré-emergência das culturas. No segundo experimento, cinco sub-doses (0; 0,3906; 0,7812; 1,5625 e 3,125 g i.a. ha-1) do indaziflam foram aplicadas nas espécies que não emergiram na menor dose ou concentração do herbicida no primeiro experimento. Foram avaliadas a fitointoxicação e altura de plantas (ALT) aos 3, 7, 14 e 21 dias após a emergência (DAE). Aos 21 DAE avaliou-se matéria seca de parte aérea (MSPA), de raiz (MSR) e total (MST). O aumento das doses de indaziflam provocou aumento dos sintomas de fitointoxicação e reduções nas variáveis ALT, MSPA, MSR e MST. Entre as espécies avaliadas, em monocotiledôneas na ordem: capim-braquiária, arroz, milho, trigo, aveia e em eudicotiledôneas: tomate, pepino, girassol, feijão, soja apresentam potencial para uso como bioindicadora em estudos com indaziflam. A beterraba apresentou ser extremamente sensível ao herbicida não emergindo em nenhuma das doses estudadas.The indaziflam herbicide presents residual activity in the soil and may become a problem for agricultural crops, due to the possibility of carryover in successor crops. Thus, the objective was to select potential bioindicator species for the presence of indaziflam residues in the soil. Two experiments were carried out in a greenhouse using 0.000250 m3, both distributed in a randomized complete block design with four replicates. In the first experiment, eleven species with potential use as bioindicators were used: rice, oats, beet, brachiaria grass, beans, sunflower, corn, cucumber, soybean, tomato and wheat submitted to seven doses of indaziflam (0; 6.25; 12.5; 25; 50; 75 and 100 g a.i. ha-1) in pre-emergence of crops. In the second experiment, five sub-doses (0, 0.3906, 0.7812, 1.5625 and 3.125 g a.i. ha-1) of indaziflam were applied to the species that did not emerge at the lowest dose or concentration of the herbicide in the first experiment. The phytotoxicity and plant height (ALT) were evaluated at 3, 7, 14 and 21 days after emergence (DAE). Dry matter of aerial part (MSPA), root (MSR) and total (MST) was evaluated at 21 DAE. Different levels of tolerance of the species to indaziflam were observed. Increased indaziflam doses caused increased phytotoxicity symptoms and reductions in ALT, MSPA, MSR and MST. Among the evaluated species, in monocotyledons in the order: signal grass, rice, corn, wheat and oats in eudicots: tomato, cucumber, sunflower, beans e soybean present potential for use as a bioindicator in indaziflam studies. The beet was extremely sensitive to the herbicide and did not emerge at any of the doses studied

Seletividade de herbicidas aplicados em pré e pós-emergência da cultura do cártamo

The cultivation of safflower has increased in recent years, mainly for the production of biodiesel. However, it is necessary to weed control in order to avoid losses in productivity. In this way, an alternative that comes up is the use of selective herbicides for culture. This study aimed to verify the selectivity of different herbicides in pre and post-emergence to the safflower crop. Two experiments were conducted adopting a randomized block design with four replicates. For the first experiment with pre-emergence applications the treatments were arranged in a 6 x 2 + 1 factorial scheme, whereas for the second experiment with the post-emergence applications the treatments were arranged in a factorial scheme 7 x 2 + 1. For both experiments, the factor A corresponded to the different herbicides and factor B at the doses used and the additional treatment consisted of control without application of herbicides. Visual evaluations of intoxication were carried out in the plants at 7, 14 and 21 days after application (DAA), plant height, stand and productivity. The application of chlorimuron-ethyl (20 e 40 g i.a. ha-1), flumioxazin (50 e 100 g i.a. ha-1), imazaquin (161 e 322 g i.a. ha-1), s-metolachlor (1440 e 24000 g i.a. ha-1) and sulfentrazone (300 g i.a. ha-1) in pre-emergence, and sethoxydim (184 g i.a. ha-1), fluazifop-p-butyl (375 e 750 g i.a. ha-1) haloxyfop-methyl (60 e 120 g i.a. ha-1) e clethodim (108 g i.a. ha-1) in post-emergence were selective for safflower.O cultivo do cártamo tem aumentado nos últimos anos, principalmente para a produção de biodiesel. O controle de plantas daninhas a fim de evitar perdas na produtividade da cultura faz se necessário. Desta forma, uma alternativa que surge é o uso de herbicidas seletivos para a cultura. Objetivou-se verificar a seletividade de herbicidas em pré e pós-emergência para a cultura do cártamo. Foram conduzidos dois experimentos adotando-se delineamento em blocos casualizados com quatro repetições. Para o primeiro experimento com aplicações em pré-emergência os tratamentos foram arranjados em esquema fatorial 6 x 2 + 1, enquanto que para o segundo experimento, com as aplicações em pós-emergência os tratamentos foram dispostos em esquema fatorial 7 x 2 + 1. Em ambos experimentos, o fator A correspondeu aos diferentes herbicidas e o fator B às doses utilizadas, e o tratamento adicional consistiu de testemunha sem aplicação de herbicidas. Foram realizadas avaliações visuais de fitointoxicação nas plantas aos 7, 14 e 21 dias após a aplicação, altura de plantas, estande e produtividade. Os herbicidas chlorimuron-ethyl (20 e 40 g i.a. ha-1), flumioxazin (50 e 100 g i.a. ha-1), imazaquin (161 e 322 g i.a. ha-1), s-metolachlor (1440 e 24000 g i.a. ha-1) e sulfentrazone (300 g i.a. ha-1), aplicados em pré-emergência, e os herbicidas sethoxydim (184 g i.a. ha-1), fluazifop-p-butyl (375 e 750 g i.a. ha-1) haloxyfop-methyl (60 e 120 g i.a. ha-1) e clethodim (108 g i.a. ha-1), aplicados em pós-emergência foram seletivos para a cultura do cártamo

Glyphosate effects on sugarcane metabolism and growth

Glyphosate is the most widely used herbicide in the world. In sugarcane, it is used as a herbicide when applied at its field rate, but it is also used as ripener when applied as low doses. However, the effects of glyphosate on plant metabolism and sugarcane growth are not fully understood. This study aimed to evaluate the metabolic changes and the effects on sugarcane plant growth caused by the application of different doses of glyphosate. Sugarcane plants were grown in a greenhouse and subjected to glyphosate applications at doses of 7.2; 18; 36; 72; 180; 360 and 720 g a.e. ha-1. Plants grown without an herbicide application were used as a control. Plants from each treatment were collected at 2, 7, 14, and 21 days after treatment (DAT) application to quantify the levels of shikimic acid, quinic acid, shikimate-3-phosphate, glyphosate, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), phenylalanine, tyrosine, and tryptophan. Visual evaluations of plant intoxication were performed at the same time as the collection of plants, and the quantification of their shoot dry biomass was performed at 21 DAT. At doses of glyphosate greater than 72 g a.e. ha-1, increases in the levels of shikimic acid, quinic acid, and shikimate-3-phosphate occurred and AMPA was detected in the plants. Initially, glyphosate caused increases in the plant levels of phenylalanine and tyrosine at doses of 72 and 180 g a.e. ha-1, although a decrease in the levels of aromatic amino acids subsequently occurred at and above the doses of 72 or 180 g a.e. ha-1. The doses ranging from 7.2 to 36 g a.e. ha-1 promoted an increase in plant shoot biomass, and doses greater than 72 g a.e. ha-1 caused significant reductions in dry mass.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP