In vitro induction of autooctoploid asparagus genotypes

Octoploid genotypes of Asparagus officinalis L. cv. 'Morado de Huetor', a tetraploid Spanish landrace, were successfully induced by treating in vitro rhizome buds explants with colchicine. Pulses during 24 h with different concentrations of colchicine are able to induce polyploid plants, colchicine applied at 0.1 % induce a 7 % of octoploid genotypes with a stable ploidy level and a 3.5 % of mixoploid genotypes. The maximum rate of mixoploid genotypes (26 %) was obtained with 0.3 % colchicine. The plant survival and rooting rates of explants decrease for increasing doses of colchicine. All octoploid genotypes were micropropagated, rooted, transplanted and successfully acclimatized (100 %) in a glasshouse. The four octoploid plants recovered show significantly better agronomical parameters such as spear diameter, canopy area and shoot length than the original tetraploid plants and histological studies confirm the size increase of octoploid cells respect the original tetraploid cells.