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COSTA, Marcus Antônio Gonçalves et al. Defoliation levels during reproductive stages of soybean cv. Ocepar 14, under two tillage systems. Cienc. Rural [online]. 2003, vol.33, n.5, pp.813-819. ISSN 0103-8478. http://dx.doi.org/10.1590/S0103-84782003000500004.
This study aimed to evaluate the defoliation levels under reproductive stages, of soybean cv. Ocepar 14, over no-tillage and conventional tillage systems. Two experiments were conducted, during the 1998/99 growing season, in Santa Maria, in the State of Rio Grande do Sul, Brazil. The defoliation levels were 0, 33, 67 and 100%. Total defoliation decreased grain yield significantly when performed at R3, R4, R5 and R6 stages in both no-tillage and conventional tillage. Total defoliation was more prejudicial to yield at R4 in no-tillage, while R4 and R5 were more sensitive to full in conventional tillage. Defoliations of 33 and 67% decreased grain yield only when applied at R3 stage in the no-tillage system. In the conventional tillage, only defoliation of 67% caused significant reductions on yield in R5 stage. There was no difference between soil tillage systems in the percentage of yield reduction promoted by any of the evaluated defoliation levels.
Keywords : Glycine max; damaged plants; no-tillage; conventional tillage.