IRRADIATION AND POLYAMINES IMPACT ON GROWTH TRAITS OF GRECIAN FOXGLOVE (DIGITALIS LANATA L.) CULTIVATED IN VITRO ROOTING

Abstract

Grecian foxglove (Digitalis lanata L.) is an ornamental plant rich in cardiac glycosides, which stimulates heart activities and achieves greater attention for propagation through various traditional methods and modern tissue culture using gamma irradiation alone and in combination with polyamines. The recent study aimed to screen and select the effective doses and concentrations of irradiation and polyamines, respectively, for better growth traits of Digitalis lanata. The D. lanata seeds were irradiated with gamma-ray doses (0, 25, 50 grays [Gy]), and the spermidine (SPD) was used with various concentrations (0.0, 0.5, 1.0, 1.5, and 2.0 mg L-1). The results showed the superiority of gamma radiation with a dosage of 50 Gy by achieving the highest average germination rate of 100% (7.10 seeds day-1). In the rooting experiment, results further indicated that the radiation treatment (50 Gy) also excelled over other treatments, giving the highest percentage of rooting and root number, and root length, as well as, fresh and dried weights of root total, with values of 65.80%, 41.18 roots plant-1, 3.83 cm, 1.90 mg, and 0.90 mg, respectively compared with neutral (control) treatment. Concerning the effect of polyamine, the concentration of 1.5 mg L-1 proved to lead by producing the highest percentage of rooting and root number, roots length, as well as, fresh and dried weights of root total, amounting to 73%, 54.18 roots plant-1, 4.21 cm, 2.25 mg, and 1.19 mg, respectively compared with control. Low-dose gamma irradiation affected the seed germination and growth traits of D. lanata. The individual use of spermidine (polyamine) also enhanced the root number and length.