A deriva de glyphosate interfere no desenvolvimento e produtividade de arroz irrigado

The objective of this research was to evaluate the injury to the development and yield of early cycle flooded rice cultivar (IRGA 430), caused by simulated glyphosate drift. The experiment was carried out in the field at the Experimental Station of the Rice - IRGA, in the 2016/17 season, and treatments were arranged in factorial scheme 3x2+1 whose factor A consisted of the glyphosate drift simulation with rates of 135; 270 and 540g ha-1 a.e.; the factor B of two nitrogen (N) rates, being 90 and 121.5 kg ha-1 N; more control without application of glyphosate and with the application of 90 kg ha-1 N. There increase in glyphosate rate results in higher injuries to the crop, with phytotoxicity symptoms, less panicles per area, and about 60% yield loss. The period of emergency until the anthesis (R4) was prolonged. The glyphosate simulated drift shows higher phytotoxicity, lesser plant height and increase development cycle, promoting negative interference on flooded rice yield.Objetivo do trabalho foi avaliar os danos ao desenvolvimento e produtividade de cultivar de arroz irrigado de ciclo precoce (IRGA 430), ocasionados por deriva simulada de glyphosate. O experimento foi realizado a campo na Estação Experimental do Arroz – IRGA na safra 2016/17 e os tratamentos foram arranjados em esquema fatorial 3x2+1 cujo fator A constou da simulação de deriva de glyphosate nas doses de 135; 270 e 540g ha-1 e.a.; o fator B de duas doses de nitrogênio (N), sendo eles 90 e 121,5 kg ha-1 de N; mais testemunha sem aplicação de glyphosate e com aplicação de 90kg ha-1 de N. O aumento na dose de glyphosate resultou em maiores danos à cultura, como sintomas de fitotoxicidade, redução no número de panículas por área e no rendimento de grãos que foi de aproximadamente 60% na maior dose estudada. De acordo com o aumento da dose de glyphosate também ocorreu o prolongamento no número de dias entre a emergência da cultura até o estágio de desenvolvimento de antese (R4). A deriva simulada de glyphosate evidencia que o herbicida causa elevada fitotoxicidade a cultura, menor estatura as plantas e aumento do ciclo de desenvolvimento, interferindo negativamente na produtividade da cultura do arroz irrigado

Antagonism between fungicide-insecticide treatments and dietholate in irrigated rice seeds

Abstract: The plant safener dietholate can be used for seed treatments (ST) to improve the selectivity of clomazone in rice cultures, thus allowing the application of higher dosages of this herbicide. The objective of this research was to evaluate the interaction between seed fungicide-insecticide treatments with and the plant safener dietholate in irrigated rice. Three experiments were carried out, and the first of them was conducted in a laboratory, following a completely randomized experimental design with four replications. Different ST and treatment-to-sowing intervals were evaluated. The second and third experiments were performed in field conditions, in a completely randomized block design with four replications. In experiment two, seeds were treated with different fungicides, in association or not with dietholate; while in experiment three, the effect of the ST with fungicides and dietholate with clomazone application were assessed. The results evidenced that the association between carboxin + thiram + dietholate reduced seed germination, vigor, and the dry mass of shoot of rice plants. The longer it takes between ST and sowing, the more rice seed germination is negatively affected. The association between fungicides and dietholate may have been antagonistic, and thus interfered with the culture growth potential