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Abstract
‘Great Lakes R-200’ (Lactuca sativa L.). seedlings were fertilized with preplant-incorporated 8N-14P-7K at 0-32 g/liter of medium and combined with daily misting of 13N-11P-21K at 0-1800 ppm using 6 different media. The recommended foliar range is 200—600 ppm combined with preplant incorporation of 0—8 g/liter of medium. The 200 ppm foliar treatment required 4—8 g/liter of medium-incorporated fertilizer while the 600 ppm foliar treatment required 0—4 g/liter. The 0 foliar treatment decreased seedling weight, head firmness, and head weight. The 1800 ppm foliar rate is undesirable since it can decrease head size and percent salable heads, and cause soft seedlings. Large differences among treatments at the seedling stage moderated at hearvest time. The highest preplant rates (16—32 g 8N-14P-7K/liter of media) caused excess salinity and this resulted in delayed seed germination and reduced seedling fresh weight. Total salable weight and average head weight were not influenced by any of the 6 media tested. However, a lower seedling fresh weight occurred with 1 medium in the first experiment and 2 media in the second experiment.