EFFECTS OF TEMPERATURE AND FERTIGATION ON LETTUCE SEEDLING PRODUCTION USING PEAT BLOCKS
The "peat blocks system" has been developed in France for the preparation of vegetable transplants and is still in use mostly in Western Europe. The blocks are made mostly of brown peat moulded into cubes that retain their shapes for the whole transplant raising period. This allows for transplanting much younger plants than what is required with multicellular trays and reduces greatly the transplanting shock. Indeed, since the peat blocks hold themselves, there is no need for roots to fully exploit the entire volume of the substrate for planting to be possible. Growth resumes quickly and the production cycle is dramatically reduced. The potential of peat blocks for improving lettuce production in Quebec has been evaluated from several angles and found promising, provided that adjustments are made to the respective contributions in nutrients coming from the substrate vs. fertigation. An experiment was conducted in two growth cabinets (20 or 30°C daytime temperature) with Boston lettuce var. Sinatra and Iceberg var. Ithaca. Fertility treatments consisted of two substrate fertility levels (poor, rich) and two fertigation treatments (0 or 200 ppm N). Measured parameters were chlorophyll status, leaf length, number of leaves, fresh and dry shoot matter, and specific leaf weight. The rich substrate coupled to fertigation led to excessive shoot growth of the Boston, which appeared particularly sensitive to fertility status. Only the rich substrate fertility status affected Icebergs growth positively. Balanced fertility is a key component of the peat blocks production system since it has an impact on the risks of salinity damages to the young stem as well as the weight and quality parameters of the harvested crop.
Maltais, A., Gosselin, A., Tremblay, N. and Van Winden, D. (2008). EFFECTS OF TEMPERATURE AND FERTIGATION ON LETTUCE SEEDLING PRODUCTION USING PEAT BLOCKS. Acta Hortic. 782, 367-374
substrate fertility levels, salinity, nitrogen, temperature, chlorophyll status, shoot growth