The effect of seed treatment and seed covering medium on the establishment of crisp lettuce

SUMMARY Three experiments examined the effects on seedling emergence and seedling weight of covering pelleted, natural and pre-germinated seeds of the variety Pennlake with soil and other media. Covering seeds with a peat-vermiculite mix gave significantly greater, earlier and more uniform emergence and seedlings with a lower coefficient of variation (c.v.) of weight than covering with soil. Seedlings from pre-germinated seeds emerged more rapidly than those from natural and pelleted seeds and tended to be heavier when harvested 24 or 41 days after emergence. However, natural seeds consistently gave more uniform emergence than the other seed treatments and the lowest c.v. of seedling weight.