ISHS Acta Horticulturae 559: V International Symposium on Protected Cultivation in Mild Winter Climates: Current Trends for Suistainable Technologies
EFFECTS OF LIGHTING ON THE GROWTH, QUALITY AND PRIMARY NITROGEN ASSIMILATION OF GREENHOUSE LETTUCE (LACTUCA SATIVA. L) |
| Authors: | H. Chadjaâ, L.P. Vézina, M. Dorais, A. Gosselin |
| Keywords: | Lactuca sativa, tipburn, supplementary lighting, nitrate reductase activity, nitrates |
| DOI: | 10.17660/ActaHortic.2001.559.48 |
| Abstract:
Two lettuce cultivars (Lactuca sativa L., cvs Berlo and Rosana) were subjected to three light treatments in the greenhouses at Laval University. Two types of supplementary lighting; high pressure sodium (HPS) and metal halide (MH) lamps were compared with natural light in a greenhouse experiment. The use of those two types of lamps provided a PPF of 50 µmol m-2 s-1 of supplementary light to 16 hours. Supplementary lighting significantly increased plant fresh weight, tipburn ratings, head firmness but reduced nitrate accumulation in the leaves. Further analyses suggested that the decrease in nitrate content was related to increased reduction rates by leaf nitrate reductase. The most pronounced effects were obtained with HPS lighting, namely fresh weight gains of up to 70% and reduction in nitrate content of about 25%. Heading was not affected by the type of lamp used. Berlo cultivar proved to be more sensitive to tipburn than Rosana. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
