This study was conducted in the experimental area of the Plant Pathology Department of the Agronomy Faculty "Eliseu Maciel" of the Federal University of Pelotas, in 2001 and 2002 with the objective of evaluating the effect of using seeds with different vigor levels on emergence and initial seedling growth. Seeds of two vigor levels were tested, and the higher vigor had more than 95% germination and the lower vigor level germination was between 80 and 85%. Those lots were obtained from officially documented seed growers of Rio Grande do Sul State, Brazil. The use of low vigor seeds caused a reduction in field emergence, delayed and unequal emergence and continued to act after emergence on isolated plants, affecting biomass dry weight and foliar area. Thus it was an advantage to use seeds of higher vigor level due to the production of plants with a big initial size, that consequently, propitiated bigger growth crop rate. Differences in crop growth rate decreased during the growing period because of the bigger relative growing rate shown by plants from low vigor seeds, although there was no variation in the rate of liquid assimilation. This behavior led to a reduction in the initial differences of biomass yield by isolated plants of irrigated rice, derived from seeds of different vigor levels.
Oryza sativa L.; seed quality; field emergence; growing rate; stablishment crop
