COLCHICINE INDUCED TETRAPLOIDS OF RADISH (Raphanus sativus L.)

Abstract

Radish (Raphanus sativus L., Brassicaceae) is an edible root crop cultivated all over Sri Lanka. So a few attempts have been made in Sri Lanka to improve crop for higher yield and wider adaptability. Therefore the present study was carried out to improve the Radish (Raphanus sativus L.); variety Beeralu through colchine. Petiole ex plants from in vitro regenerated plants were used to induce tetraploid by colchine chemical. The different concen trations of colchicine 0, 30, 60 and 120mgl- were used. After 30 days interval colchicine treated petiole explants were transferred to the MS medium with 2.5mgl-1BAP concentration without colchicine. Then effects of different time durations (5, 10, 15, 20 and 25 days) were examined using petiole explants in selected best colchine concen tration (60mgl-1 ) from the above trial. Cell samples of the root tips were used to identify chromosomes and sto mata were observed from epidermal layer of leaves under a microscope (Axio Lab A1) and photos were taken with the associated apparatus to confirm ploidy level. Experiments were arranged according to a Completely Ran domized Design (CRD) with five replicates and repeated four times with minimum of four replicates. Roots were induced MS medium with 0.25mgl-1 IBA. Highest percentage (25.27%) of tetraploid plantlets induction obtained from MS basal medium treated with 60mgl-1 colchicine for 20 days. Highest stomata length and width (467.54µm, 395.75µm) was observed from tetraploid plantlets while lowest leaf length (25.11cm), lowest root length(16.67cm) and highest leaf width (7.12cm) were reordered in acclimatized tetraploid plants.