Interference periods of weeds in cassava crop, submitted or not to NPK fertilization, in Vitória da Conquista-Ba

Abstract

The objective of this study was to evaluate the phytosociological survey and determine the critical periods of weeds competition with the cassava crop, submitted or not to NPK fertilization. Therefore, the weeds were collected every 35 days, until 525 days after cassava planting, through the random release of a cast iron square 0.5 m x 0.5 m (0.25 m2) in plots with and without fertilization. The plants inside the square were cut close to the ground, counted and identified by species. Sida rhombifolia, Brachiaria plantaginea and Cynodon dactylon showed the highest FR, DR, AR and IVI. Subsequently, the yield data of storage roots were adjusted to non-linear regression model sigmoidal Boltzmann to determine the critical periods of competition: PAI, TPIC and PCPI. The fertilizer supplied to cassava crop contributed to the determination of different phytosociological indices and critical periods of competition.