Effect of propagation cell density and use of a nursery stage on plant growth of 'Rex' lettuce in hydroponic production
Seed of 'Rex' lettuce (Lactuca sativa) were sown into polyphenolic resin foam sheets of which the planting densities were 50, 104, 162, and 276 cells per sheet. A single seed was sown per cell and sheets were placed into sub-irrigation propagation trays. For each cell density, seedlings were transferred to NFT nursery channels at a one-true-leaf stage (1TL), two-true-leaves stage (2TL), or they were never (N) transferred to nursery channels. All seedlings transferred or not transferred to a nursery stage were transferred to NFT finishing channels at a four-true-leaves stage. Data collected at harvest were shoot fresh weight, shoot dry weight, and lettuce head diameter. Days to four true leaves were also recorded. Nursery transfer stage and substrate cell density did not have a significant effect (α=0.05) on time to four true leaves for seedlings, shoot fresh weight and dry weight, or head diameter of plants at harvest. Seedlings can remain in the propagation stage until they reach four true leaves without negative effects on lettuce growth and development. By leaving seedlings in propagation until four true leaves, growers can save labor costs and maximize space usage.
Evans, M.R. and Quick, H.R. (2019). Effect of propagation cell density and use of a nursery stage on plant growth of 'Rex' lettuce in hydroponic production. Acta Hortic. 1266, 145-152
nutrient film technique, nursery, substrate