Qualidade e pH das águas de propriedades citrícolas e de rios da Amazônia Central sobre a eficiência do glifosato no controle de Brachiaria decumbens

Abstract

The productivity of citrus trees has not reached its full potential due to the action of various factors that directly affect the rentability of agriculture. Among these factors, has great importance the interference of weeds in citrus orchards in the metropolitan region of Manaus-AM.Have installed the experiment in a greenhouse, and Laboratory of Weed Science (LCPD) in the period from July to October 2013 in the Department of Plant and Animal Production (DPAV) of the Federal University of Amazonas (UFAM), Manaus-AM, with in order to characterize the chemical properties of the waters of rivers, streams and artesian producers of citrus using glyphosate, evaluate different pH values of the water on the leaf area and dry matteria production of B. decumbens and determine the period decanting that provides greater efficiency for glyphosate in the control of the plant. The experimental design was completely randomized in a factorial 7x7x4. Treatments were seven values of pH (3, 4, 5, 6, 7, 8, and natural water pH), seven origins of water spray (UFAM, Panorama Farm, FM Citric Farm, Igarapé, Black River, Solimões River and Amazon River) and periods of settling (0, 24, 48 and 72 hours) with 4 reaplications. I was evaluated the chemical composition of the water used in citrus-producing properties in the metropolitan region of Manaus, settling periods, percentage reduction in leaf area and dry weight of brachiaria a function of pH and settling periods of each of the 7 has been reported sources used in this research. The pH value between 3 and 4 was the best for reduction of leaf area and dry weight compared to control. When the decanted water by decantation period of 24 and 48 hours there was an improvement in the efficiency of control by glyphosate up to 45%. The waters of the citrus producing properties shown to be inadequate to apply glyphosate, while the waters of the Black River, Solimões and Amazon rivers also high quantities of ions and organic matter that reduced activity of glyphosate.