Micropropagation of Stevia rebaudiana (Bertoni) Bertoni using nutrient water of Cocos nucifera var. aurantiaca (King coconut) as a natural growth enhancer

Stevia rebaudiana (Bertoni) Bertoni is a herb producing zero-calorie diterpene glycosides in its leaves, which are extensively used as a substitute for sugar since they are about 200 – 400 times sweeter than sucrose. It is an economically important plant in the food and beverage industry around the world. The drawbacks associated with the conventional propagation through seeds and cuttings impede its mass production. Thus, effective in vitro micropropagation is advantageous on an industrial scale. Partial media replacement was done to the Murashige and Skoog (MS) medium with water from immature (6 – 7 months from flowering) Cocos nucifera var. aurantiaca (King coconut). Sterilized young nodal cuttings cultured on the MS medium with 10 % (v/v) coconut water (CW), without any hormones, induced 93.3 % bud break or shoot initiation from the nodes with a mean shoot length of 41.86 ± 0.85 mm. Increasing the CW to 30 % with 0.2 mg/L 6-benzylamino purine (BAP) produced the highest mean number of shoots (9.44 ± 0.51) and the highest number of leaves (8.28 ± 0.81) in three weeks. Modified rooting media incorporating only macronutrients, 0.2 mg/L of indole- 3-butyric acid (IBA) and 5 % CW without micronutrients showed the earliest rooting (6.6 days). The highest number of root initiations (13.5) was with ½ MS + 0.2 mg/L IBA + 5 % CW. Regenerated plantlets were successfully hardened and acclimatized in glass jars with compost and sand (1:3 ratio) covered with polypropylene caps under greenhouse conditions. Our results suggest that Stevia can be propagated effectively with CW incorporated media and in the future, this could be used in small-scale commercial cultivations.