Int.J.Curr.Microbiol.App.Sci (2017) 6(9): 3235-3246 3236 Original Research Article https://doi.org/10.20546/ijcmas.2017.609.398 Investigating the Effects of Exogenous Factors on Growth, Photosynthetic Pigments and Bud Induction in Gracilaria corticata var. cylindrica under In vitro Conditions A. Anuraj 1* , Ajit Arun Waman 2 , Chandra Prakash 3 , S. Dam Roy 4 , M. Viji 1 , Manoj Baidya 1 and N.K. Chadha 3 1 Division of Fisheries Science, 2 Division of Horticulture and Forestry, ICAR-Central Island Agricultural Research Institute, Port Blair, India 3 Division of Aquaculture, ICAR-Central Institute of Fisheries Education, Mumbai, India 4 Director, ICAR-Central Island Agricultural Research Institute, Port Blair, India *Corresponding author ABSTRACT Introduction In the ever expanding billion-dollar seaweed industry, production contribution is mostly from the organized culture sector, while wild harvests accounts for mere 5% of the global seaweed production (FAO, 2014). Species of Gracilaria are cultivated in many parts of the world (FA0, 2016) and forms an important natural source of phyco-colloid- agar. However, the conventionally used vegetative fragments from the same mother plants over generations have reported to decrease the agar yield and quality, apart from increasing their susceptibility to various diseases (Hurtado and Chenney, 2003). Micropropagation is an in vitro culture technique, wherein axenic explants from any part of the seaweed are used to develop clones in artificial media under controlled conditions. Utility of in vitro multiplication techniques has been emphasized for commercial scale seaweed culture (Bohra et al., 2017). Supply of good quality seed material through in vitro means could improve the yield significantly through improved growth and phyco-colloid recovery, International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 9 (2017) pp. 3235-3246 Journal homepage: http://www.ijcmas.com Effect of kind and concentration of culture media, and plant growth regulators on in vitro response was studied in an economically important seaweed species viz. Gracilaria corticata var. cylindrica. Filter sterilized autoclaved artificial seawater medium at 100 % concentration (A 2 ) was found to be the most optimum for in vitro culture as the cultured explants showed superiority in terms of growth and photosynthetic pigment content, apart from inducing lateral bud formation. Incorporation of cytokinin alone or in combination with auxin (IAA) promoted growth of seaweed explants in A 2 media.A 2 medium supplemented with kinetin at different concentrations showed the highest total chlorophyll content (K 2 ), highest total carotenoid content (K 3 ) and better induction of lateral buds (K 1 ). Hence, considering the promising response of artificial seawater supplemented with cytokinins and auxin for in vitro culture of the species, the present investigation could serve as a base study for formulating future research programmes. Keywords Rhodophyta, Seaweed, Media, PGR, Explants. Accepted: 28 August 2017 Available Online: 10 September 2017 Article Info