ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
STUDIES ON IRRIGATION SYSTEMS TO GROW LETTUCE (LACTUCA SATIVA L.) TRANSPLANTS |
| Authors: | S. Nicola, J. Hoeberechts, E. Fontana |
| Keywords: | flotation, Ebb-and-Flow, growing media, containerized cell-trays |
| Abstract:
Lettuce seedlings of high quality and vigor are produced in greenhouse for transplanting in the field. During the last two decades many commercial horticultural growers changed from soil-based systems to artificial substrate systems, to control plant growth. Therefore, different substrates have been used, like rockwool, organic substrates (peat), wood fiber, glasswool, synthetic polymers, polyester or viscose fleece, sand of coarse. Moisture and water content of the growing medium play an important role, affecting root and shoot growth, and are particularly determined by the irrigation system used during Vegetable Transplant Production (VTP). The objectives of the present research were to study the effects of different cultural techniques (substrate mixture and irrigation management) during VTP on plant growth, development, partitioning and on root architecture of lettuce (Lactuca sativa L.) seedlings. Containerized lettuce transplants were raised in medium prepared with peat (fixed at 30% in volume), styrofoam (variable) and rockwool (variable) and irrigated throughout the experiments with different irrigation systems. Traditional overhead irrigation systems were compared to sub-irrigation systems. Different media used created different conditions for root growth, as well as for water transport and storage. Results confirmed that in lettuce overhead irrigation increases basal root number and root:shoot ratio with respect to sub-irrigation systems. Overhead irrigation may have provided uniform moisture levels around the seedling hypocotyls, thus enhancing basal root differentiation. Cutting fertilizer costs and reducing disease occurrence are certainly the two main advantages of the sub-irrigation systems. However, transplant quality through enhancement of root mass was improved by an overhead irrigation system. | |
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