Suitability of three vigour test procedures to predict field performance of early sown maize seed

Early spring sowing in maize requires seed capable of germinating and emerging promptly in cold and wet soils, and in this respect the availability of laboratory methods with high predictive value is relevant. This work was aimed at comparing the suitability of three vigour tests to predict field performance, under unfavourable conditions, of maize (Zea mays L.) seed lots of high germination potential. Thirty lots, all with a standard germination (SG) higher than 92%, were submitted to a cold test in sand (CT), a soak test (ST) and accelerated ageing (AA), and their performance in the field was assessed in early sowing at one site. A wide range of seed vigour was detected by the three tests, and in particular by the AA test, as well as a wide variation in field performance (final emergence, mean emergence time, mean emergence rate) as a consequence of the rather low soil temperatures. The CT showed the highest correlations with field performance, and ST the lowest, presumably due to the good aeration of the seedbed; the vigour of seed lots, as detected by the AA test, was more strongly affected by seed age than that revealed by other vigour tests or by field traits.