Adaptation of Hydrangea macrophylla regenerants to non-sterile ex vitro conditions

Abstract

Hydrangea macrophylla is a decorative blossoming shrub used in landscape gardening. Its mass regeneration is implemented through reproductive sterile in vitro culturing. The plant adaptation to ex vitro conditions is the most delicate final stage, when the shoots are frequently treated with biostimulators to improve growth, development and immunity. We aimed to study the adaptation of in vitro-cultivated Hydrangea macrophylla regenerants to non-sterile conditions. The following solutions were used in adaptation trials: 1) HB-101, containing silicon dioxide as the active component, extracted from pine wood and sap, plantain, cypress and cedar, that functions as a universal plant immunity and development vitaliser; 2) Zircon, containing a complex of hydroxycinnamic acids and their derivatives, stimulates rooting during adaptation and acts as a stress protector; 3) Epin, a natural brassinosteroid plant hormone, that displays anti-stress adaptogenic and strong growth-stimulating activity; 4) Plant, a natural organic fertiliser, which enhances plant nutrition and rooting. This article describes the in vitro — ex vitro adaptation in different Hydrangea macrophylla cultivars (Draps Wonder, Madame Hamard and Bichon) and the impact of different biopreparations (HB-101, 0.5 mL/L; zircon, 0.5 mL/L; epin, 1.0 mL/L; plant, 2.5 g/L) on the biometric indices (length and number of roots, number of leaves, height of shoots) and survival rate. With respect to the cultivar, the best adaptation rate attained 95.8-100 % in the substrate treatments that used zircon (0.5 mL/L) and epin (1.0 mL/L).