University of Tehran Iranian Journal of Horticultural Science 2008-482X 48 2 2017 08 23 The effect of blue and red spectrum combinations and light intensity on vegetative growth of Petunia seedling The effect of blue and red spectrum combinations and light intensity on vegetative growth of Petunia seedling 443 446 63400 10.22059/ijhs.2017.218893.1113 FA Azadeh Rashidi Former M. Sc. Student, Faculty of Agriculture, International Campus, University of Mashhad, Iran Ali Tehranifar Professor, Faculty of Agriculture, University of Mashhad, Iran 0000-0002-7103-0413 Hossein Nemati Assistant Professor, Faculty of Agriculture, University of Mashhad, Iran Journal Article 2017 01 02 To investigate the effect of light intensity and  light combinations on vegetative characteristics of petunia seedling(Petunia × hybrida 'Super cascade Blue'), an experiment was conducted as factorial in Completely Randomized Design with three replications Seedlings were treated for four weeks under two levels of light intensity includes 40 μmol.m-2.s-1and 60 μmol.m-2.s-1and three combinations of blue and red spectrum with ratios of 0% blue: 100% red, 15% blue: 85% red, 30% blue: 70% red and Fluorescent light. The result showed that fresh weight and dry weight, leaf area and stem caliper were superior less than 65 μmol.m-2.s-1 of 15% blue: 85% red ratio. Our results implied that specific light combination was able to compensate the negative effects of low light intensity because using 15% blue: 85% red ratio with 40 μmol.m-2.s-1compared to 0% blue: 100% red, 30% blue: 70% red and Fluorescent light at 60 μmol.m-2.s-1 light intensity lead to seedlings with superior vegetative characteristics. To investigate the effect of light intensity and  light combinations on vegetative characteristics of petunia seedling(Petunia × hybrida 'Super cascade Blue'), an experiment was conducted as factorial in Completely Randomized Design with three replications Seedlings were treated for four weeks under two levels of light intensity includes 40 μmol.m-2.s-1and 60 μmol.m-2.s-1and three combinations of blue and red spectrum with ratios of 0% blue: 100% red, 15% blue: 85% red, 30% blue: 70% red and Fluorescent light. The result showed that fresh weight and dry weight, leaf area and stem caliper were superior less than 65 μmol.m-2.s-1 of 15% blue: 85% red ratio. Our results implied that specific light combination was able to compensate the negative effects of low light intensity because using 15% blue: 85% red ratio with 40 μmol.m-2.s-1compared to 0% blue: 100% red, 30% blue: 70% red and Fluorescent light at 60 μmol.m-2.s-1 light intensity lead to seedlings with superior vegetative characteristics. https://ijhs.ut.ac.ir/article_63400_cd2c073c587f99d43954d1504c732c18.pdf