Mean germination time in the laboratory estimates the relative vigour and field performance of commercial seed lots of maize (Zea mays L.)

Consistent rankings in mean just germination time (MJGT), when the radicle first appears and mean germination time (MGT; 2mm radicle) were seen in three laboratories among seven lots of maize. Both measures of germination rate (MJGT and MGT) were significantly related to shoot length, its variation and dry weight in the laboratory at 13 degrees C and 20 degrees C and to the same parameters in a field sowing in cool conditions, but not significantly to final emergence. Slow germinating lots produced shorter more variable shoots in the laboratory and emerged more slowly in the field, producing smaller and more variable plants 25 days after sowing. Single early counts (6 days at 13 degrees C and 3 days at 20 degrees C) were also related to seedling performance and are suggested as potential routine vigour tests for maize. The findings are discussed in relation to the effects of ageing on seed vigour and field emergence.