EFFECTS OF MECHANICAL DAMAGE DURING SOYBEAN SEED PROCESSING ON PHYSIOLOGICAL SEED QUALITY AND STORAGE POTENTIAL

The effects of mechanical damage during soybean (Glycine max (L.) Merr ill) seed processing on physiological seed quality and storage potenti al were evaluated. An experiment was carried out using three seed lots (three cultivars) from which seed samples were taken during processin g. In the case of the cultivar IAC-15 the sampling took place at nine points in the processing line; for the cultivars Ocepar-7 and Dourados an additional sample was manually collected before mechanical harvest . Germination and vigour (electrical conductivity, accelerated ageing and tetrazolium) tests were performed on each sample monthly, from Jul y through November. The cultivar IAC-15 (medium maturity) showed lower seed quality than cultivars Ocepar-7 (medium maturity) and Dourados ( late maturity). The mechanical damage of seed increased for IAC-15 as indicated by germination and vigour tests. The cultivar Ocepar-7 showe d lower mechanical damage and higher seed quality than Dourados. For t hese latter two cultivars there was low variation of seed duality duri ng seed processing, although it was lower than the hand collected samp le seed quality. Also seed quality was reduced as storage period incre ased. Seed processing can increase seed quality depending an the culti var and the initial seed quality. The cultivars showed a different sus ceptibility to mechanical damage, which can be influenced by seed wate r content.