TECHNIQUE DEVELOPMENT TOWARDS PRODUCTION OF AN IN-VITRO GRAFT CHIMERAIN RUBUS

In vitro grafting attempted to produce periclinal chimeras in Rubus. T he effect of plant growth regulators on the preparation of graftable m aterial, in vitro grafting 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 mu M abscisic acid or 10 mu M paclobutrazol produced 79 to 84% succ essful grafts compared to 20 to 50% successful grafts on medium contai ning Ethrel or indolebutryic acid. Percentage shoot formation from exc ised graft unions ranged between 19 and 40%, only 5 mu M indole butyri c acid significantly reduced regeneration from the more organogenic tr eatments. Regenerant shoots were primarily from the scion in ethrel, n o plant growth regulator and paclobutrazol treated graft unions. Other treatments resulted in equal numbers of shoots with scion and rootsto ck phenotypes. Although over 200 regenerants were obtained both sides of the graft union, no thornless/thorny chimeras were recovered from t he subsequent use of this technique.