Characterization of Stevia rebaudiana Bertoni polyploids for growth and quality

Polyploids of stevia were developed in Department of Horticulture, UAS Bangaluru, using different concentrations of colchicine. The induced ploidy levels, conf i rmed through flow cytometry, included diploid, triploid, tetraploid and mixaploid forms. These polyploids showed variabi lity during ini tial trials. To study the variabi li ty in morphological and quality parameters among polyploids, an experiment was conducted in f ield condition by using randomized complete block design with 10 treatments and three repl ications. Variabili ty was observed among polyploids. Triploid-T7 plants were signif icantly tal ler (83.28 cm) with maximum internodal length (3.85 cm) and primary branches (3.00). Mixaploid plants recorded signif icantly the maximum stem thickness (8.43 mm), numbers of secondary branches (24.64), leaf thickness (0.57 mm), leaf area (15.00 cm2), stem weight (114.98 g), delayed flowering (73.33 days for 50% f lowering) and highest stevioside content in leaf (13.50%). Maximum leaf area index (3.85) and rebaudioside-A content (6.21%) were recorded in tetraploid-T10. The induced polyploids showed better agronomic characters with maximum glycoside content. Hence, manipulation of ploidy level generated variabili ty and improved the quali ty in stevia.