Iron nanoparticle enhanced in vitro rooting and physiological– biochemical changes in Gerbera jamesonii var. Revolution Yellow plantlets

Summary The effects of iron nanoparticles (FeNPs) on in vitro rooting, chlorophyll content, antioxidant and hydrolysis enzyme activities, acclimatization and subsequent growth of Gerbera jamesonii var. Revolution Yellow plantlets under greenhouse conditions were examined in this study. The single shoots (2 cm in length) were cultured in different medium treatments, including: MS0 (MS medium - control), MS0 replacing 27.8 mg/L FeSO 4 .7H 2 O with FeNPs (ranging from 0 to 11.2 mg/L). The results showed that 2-cm shoots cultured in medium supplemented with 100 mM FeNPs induced in vitro rooting 2 days earlier than shoots cultured in MS0 medium. In addition, plantlet height (6.83 cm), number of main roots and lateral roots (13.00 roots and 4 roots), root length (5.27 cm), leaf length and width (2.07 cm and 1.83 cm), fresh and dry weights (1188.67 and 155 mg), dry matter ratio (13.04%), and chlorophyll a, b, a + b content (25.25, 18.35 and 43.6 mg/g, respectively) of the shoot culture in 5.6 mg/L FeNPs treatment were also recorded higher than other amounts of FeNPs and control (MS0) treatments after 4 weeks of culture. Furthermore, the enzyme activities of SOD (41.32 U/g), CAT (308.70 U/g), and APX (0.55 U/g) were higher in the 100 µM FeNPs treatment than those in the MS0 and MS-Fe treatments, and hydrolysis enzyme activities (cellulase and pectinase) showed opposite results after 4 weeks of culture. The plantlets derived from the 5.6 mg/L FeNPs treatment had the highest survival rate (93.00%) in comparison to those in MS0 medium (83.67%) and without FeNPs (73.33%) after 2 weeks under greenhouse conditions, and the early flower bud formation (10.17 weeks), increased flower diameter (7.87 cm), and peduncle length (22.17 cm) after 12 weeks. Key message Iron nanoparticles improved in vitro rooting, changed antioxidant and hydrolytic enzyme activities, increased acclimatization, growth and flowering of G. jamesonii var Revolution Yellow.