Characterization of Stevia rebaudiana Bertoni polyploids for growth and quality

摘要

Polyploids of stevia were developed in Department of Horticulture, UAS Bangaluru, using different concentrations of colchicine. The induced ploidy levels, confirmed through flow cytometry, included diploid, triploid, tetraploid and mixaploid forms. These polyploids showed variability during initial trials. To study the variability in morphological and quality parameters among polyploids, an experiment was conducted in field condition by using randomized complete block design with 10 treatments and three replications. Variability was observed among polyploids. Triploid-T7 plants were significantly taller (83.28 cm) with maximum internodal length (3.85 cm) and primary branches (3.00). Mixaploid plants recorded significantly 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% flowering) and highest stevioside content in leaf (13.50%). Maximum leaf area index (3.85) and rebaudioside-A content (6.21%) were recorded in tetraploid-TlO. The induced polyploids showed better agronomic characters with maximum glycoside content. Hence, manipulation of ploidy level generated variability and improved the quality in stevia.