Precision Planting of Lettuce1

Experiments were conducted to evaluate precision planting of single uncoated and spherically (clay) coated single seeds at 2 (uncoated only), 3, 4, 6, and 12 inches in the row. Three planters were used and compared to the conventional Planet Junior at accepted seeding rates. Sprinklers were compared with furrow irrigation. Seed emergence was superior with sprinkler irrigation. Coated seed and 6-inch spacing was not satisfactory with furrow irrigation, but was considered comparable to commercial stands with the sprinkler method (87.5% stand). In planting to a stand with a single seed every 12 inches (thus eliminating the thinning requirement), 84.4% of the desired stand was obtained with uncoated seed and sprinklers. Commercial stands most often range from 80 to 90% of the theoretical 12-inch spacing. Theoretical machine thinning of 3-inch plantings resulted in 8.6 single plants/10 ft of row indicating promise for this innovation.