effects of UV treatments on stem growth of some greenhouse crops

UV treatments lasting between 48 and 96 hours given to plug seedlings significanly reduced stem lenght in tomato, petunia and marigold. The same treatments were ineffective in ageratum. The UV treatments 50 micromol m-2 s-1, were more effective than white, 500 micromol m-2s-1, and red, 20 micromol m-2 s-1, light treatments