Nitrogen stress induction on levisticum officinale hairy roots grown in darkness and under photoperiod conditions: effect on growth and volatile components

Six-year-old Levisticum officinale (lovage) hairy root cultures were used to study the effect of eight different NH4 +:NO3 − ratios on their growth and volatile components. All cultures were kept at 24°C on orbital shakers at 80 rpm, in darkness or in a 16 h light/8 h dark photoperiod. Growth was evaluated by dry and fresh weight determination. The volatiles were isolated by distillation-extraction and analysed by GC and GC-MS. Greater growth was attained in darkness with 10:90 (control, SH medium), 50:50 and 25:75 NH4 +:NO3 − ratios, and also with SH control medium under the photoperiod condition, with a 10, 14, 12.5 and 12.5 fold increase of biomass in terms of dry weight, respectively, at the end of 42 days of growth. UPGMA cluster analysis of the mixtures of volatiles isolated from the hairy roots grown with different NH4 +:NO3 − ratios confirmed their chemical variability. Although no particular grouping was detected in relation to the NH4 +:NO3 − ratios or light conditions studied, most of the mixtures of volatiles isolated from the hairy roots were either dominated by n-octanal, (Z)-falcarinol or both components in about the same relative amounts.