Rooting and acclimatization of grapevine hybridsVitis labrusca×Vitis rotundifolia

Abstract

Rhizogenesis is an important step in micropropagation and root quality is essential for plant survival during acclimatization. Vitis rotundifolia hybrids show low rooting rate and auxin application is important for cutting propagation. This study was aimed at evaluating different concentrations of naphthalene acetic acid (NAA), 0.0, 0.2, 0.4 and 0.8 µM, in in vitro rooting and different concentrations of indolebutyric acid (IBA), 0, 2.5, 5 and 7.5 mM, in ex vitro rooting of grapevine hybrids and their survival rates after acclimatization. Hybrids between V. labrusca × V. rotundifolia used were: IBCA125 (‘Isabel’ × ‘Carlos’), IBBT481 (‘Isabel’ × ‘Bountiful’), and IBMG628 (‘Isabel’ × ‘Magnolia’). Explants were nodal segments from in vitro plants after the tenth subculture in medium MS/2 without growth regulators. For in vitro rooting after 30 days of cultivation at different NAA concentrations, pre-acclimatization of explants was carried out with gradual opening of bottles. After evaluations on the 34th day plants were transferred to tubes containing vermiculite and left in intermittent mist for 21 days. For ex vitro rooting, shoots were standardized in microcuttings with two leaves and treated with different IBA solutions. Microcuttings were planted in tubes with vermiculite under intermittent mist for 30 days. There was 100% rooting in all treatments for the hybrids tested. For in vitro rooting, survival was high for all hybrids, except for IBBT481, for which the highest survival rate observed was 42.1% in the treatment without NAA. For IBCA125 the survival rate decreased gradually with the increasing NAA concentration and the lowest rate observed was 0.8 µM. For ex vitro rooting, the highest survival rate was observed in the control and in the treatment with 2.5 mM of IBA for IBMG628. Survival of hybrid IBCA125 was not affected by IBA. Hybrids between V. labrusca × V. rotundifolia can easily root both in vitro and ex vitro without exogenous auxins.