Participação do nitrogênio na indução de injúrias foliares e na eficácia do herbicida glyphosate

Abstract

Nitrogen participation in the induction of foliar injury and glyphosate efficacyThree experiments were carried out, two in greenhouse and one in the field to evaluate different aspects of nitrogen participation in the induction of leaf injuries and glyphosate efficacy. Glyphosate was applied in combination with urea (U), ammonium sulfate (AMS) and U+AMS; following N soil fertilization and spray solutions with N concentrations up to 20%. Application of nitrogen spray solutions did not provide satisfactory desiccation of the different plant species, reaching maximum damage of about 30%. The use of AMS or U+AMS as a spray vehicle for glyphosate application increased control of morning glory (Ipomoea triloba L.). Nitrogen solutions accelerated glyphosate-desiccation of Johnsongrass (Sorghum halepense L.), however with no visible differences at 28 days after application. The choice of adequate glyphosate rate (1,800 g ha -1) for Brachiaria decumbens Stapf desiccation was fundamental for reaching high control, and the only alternative that enhanced the efficacy of glyphosate lower rate was the previous fertilization of the soil with 150 kg ha -1 of ammonium sulfate.Key words: Ipomoea triloba L., Sorghum halepense L., no-tillage, desiccation. Com o objetivo de avaliar diferentes aspectos da participação do nitrogênio na indução de injúrias foliares e na eficácia do herbicida glyphosate, foram desenvolvidos três experimentos, sendo dois em casa de vegetação, com as espécies Avena strigosa e Ipomoea triloba + Sorghum halepense, e um em campo, com Brachiaria decumbens. Avaliou-se a aplicação de glyphosate combinado com ureia (U), com sulfato de amônio (SA) e com U+AS, além de fertilização prévia do solo com nitrogênio e pulverização de caldas concentradas com até 20% de N. A pulverização de caldas concentradas com até 20% de N não dessecou adequadamente as espécies A. strigosa e B. decumbens, provocando danos máximos de cerca de 30%. A utilização de solução de SA ou de U+SA como veículo de pulverização do glyphosate elevou o controle de I. triloba. As soluções nitrogenadas aceleraram a atividade do glyphosate para dessecação de S. halepense, porém, sem diferenças visíveis aos 28 dias após aplicação. A escolha da dose adequada de glyphosate (1.800 g ha -1 ) para dessecação de B. decumbens foi fundamental para obtenção de elevado controle, sendo que a única alternativa que elevou a eficácia da menor dose do produto foi a fertilização prévia do solo com 150 kg ha -1 de SA. Palavras-chave:Ipomoea triloba L., Sorghum halepense (L.) Pers., plantio direto, dessecação. 517Participação do nitrogênio na indução de injúrias foliares e na eficácia do herbicida glyphosate 1

Interaction between nitrogen, soil water condition and herbicides in Urochloa plantaginea control in irrigated rice crop

“…In a study carried out with the herbicide glyphosate (360 g ha -1 ) in the control of morning glory (Ipomoea triloba L.) and johnsongrass (Sorghum halepense (L.) Pers.) species(s), it was found that the previous soil fertilization with 3 kg ha -1 of ammonium sulfate promoted greater control when compared to the others that used the same dose, in the evaluations carried out at 21 DAA (Carvalho et al, 2011). This result is similar to that observed by Sonderskov et al (2012) in control of Album chenopodium L. and Tripleurospermum inodorum (L.) Schultz Bip.…”

Aplicação de glyphosate associado a resíduo não-purificado da produção de biodiesel: análise de diferentes protótipos

“…Five adjuvants prototypes were produced from such crude residue, which were later used in the experiments (Table 2). In the experimental plant nursery, morning glory (Ipomoea triloba L.) was used as bioindicator, due to its control difficulty with glyphosate herbicide (Carvalho et al, 2011). The experiment was carried out from March to April, 2013.…”

Susceptibility of Perennial Tropical Forage Plants to Glyphosate Herbicide in Integrated Crop-Livestock Farming Systems

“…Perennial forage plants are controlled with the use of systemic herbicides (Costa et al, 2013), such as glyphosate and sulfosate; the herbicide dose and the time required for control are variable among forage species and weeds (Carvalho et al, 2011;Silva et al, 2013, Ceccon andConcenço, 2014). The desiccation interval, which is the period between herbicide application and sowing of the new crop, ranges from 7 to 21 days, and the glyphosate dose ranges from 0.72 to 1.44 kg a.e.…”