USE OF UV-RADIATION FOR CONTROL OF HEIGHT AND CONDITIONING OF TOMATO TRANSPLANTS (LYCOPERSICON-ESCULENTUM MILL.)

Treatments in greenhouse of plug transplants of tomato (Lycopersicon e sculentum Mill. CV. Marmande) with supplemental UV radiation from fluo rescent lamps were performed to control plant height and to condition them to outdoor conditions. Our investigation examined how tomato tran splants responded to varying doses of UV radiation at different time o f year (winter-spring). UV treatments, depending on the dose, signific antly lowered plant height (up to 47%), leaf area (up to 65%) and shoo t dry weight (up to 56%). The effects of UV treatments depended on bot h the daily applied dose and the environmental conditions. UV treatmen ts were effective on tomato plants in winter, i.e., in the presence of low PAR, as well as in spring, i.e., in presence of high PAR. The mai n effect of the presence of high PAR was the enhancement of the thresh old dose of UV energy required for induction of evident morphological damage to tomato plants. Blooming time and early production was simila r in untreated and W-treated plants, irrespective of the presence of t he severe reduction of growth produced by UV radiation. (C) 1997 Elsev ier Science B.V.