Improvement Of Orchid Vanda Hybrid (Vanda limbata Blume X Vanda tricolor Lindl. var. suavis) By Colchicines Treatment In Vitro

The purpose of this research was to evaluate the growth phase of orchid Vanda hybrid (Vanda limbata Blume X Vanda tricolor Lindl. var. suavis) response with colchicines treatment, to determine precise effective concentration of colchicines and duration of treatment to induce polyploidy. This research used variation of colchicines concentration which were 0.01%; 0.05%; 0.1%; 0.5%; 1% and 0% and incubation for 6 hours; 12 hours; 18 hours; 24 hours; and  4 days. Treatment was done in aseptic condition using protocorm aged 7 week after sowing. After treatments, plants were planted on Vacint and Went (VW) medium supplemented with of 150 ml/l coconut water. After four months, they were subcultured in medium VW + 150 ml/l + 150g/l banana extract. The results showed that the orchid Vanda hybrid was intolerant to colchicine concentration of 0.1; 0.5 and 1% by death protocorm was more than 50%. Concentration of 0,5% with 6 hours soaking time is the most effective to induced tetraploid in orchid Vanda hybrid. Morphological characters of tetraploid plantlets had lower average number and length of roots, the number, length, and width of the leaves than those of control. Anatomical characters of the tetraploid plantlets revealed the highest stomatal size and had smaller of stomatal index than controls. This evident indicated a negative correlation between stomatal index and ploidy level. Cytological analysis with flow cytometry revealed that tetraploid plantlets (2n=4x=76) stained with DAPI showed the chromosome number more than those of control (2n=2x=38).Key words      : polyploidization, colchicine, vanda orchid, chromosome number