Technique Development Towards Production of an In VitroGraft Chimera in Rubus

Abstract

In vitrografting was attempted to produce periclinal chimeras in Rubus. The effect of plant growth regulators on the preparation of graf table material, in vitrografting and regeneration of shoots from graft union tissue was investigated on two thornless and two thorny blackberries. Grafted plants grown on medium containing no plant growth regulators, 1 μM abscisic acid or 10 μM paclobutrazol produced 79 to 84% successful grafts compared to 20 to 50% successful grafts on medium containing Ethrel or indolebutryic acid. Percentage shoot formation from excised graft unions ranged between 19 and 40%, only 5 μM indole butyric acid significantly reduced regeneration from the more organogenic treatments. Regenerant shoots were primarily from the scion in ethrel, no plant growth regulator and paclobutrazol treated graft unions. Other treatments resulted in equal numbers of shoots with scion and rootstock phenotypes. Although over 200 regenerants were obtained from both sides of the graft union, no thornless/thorny chimeras were recovered from the subsequent use of this technique.