High throughput in vitro micropropagation of sugarcane (Saccharum officinarum L.) from spindle leaf roll segments: Cost analysis for agri-business industry

High throughput micropropagation (HTM) protocol in sugarcane through direct shoot regeneration comprising five stages, was developed for agri-business industry. The distinction of the protocol lies in direct adventitious shoot regeneration without an intervening callus phase and liberty over the number of subculture passages leading to high rates of synchronous plant production. Stage 0 dealt with selection and maintenance of field-grown stock plants; Stage I marked the initiation of in vitro propagation on culture initiation medium using spindle leaf roll segments from apical tops; Stage II involved five passages (of 14 days each) on shoot multiplication medium followed by one additional passage (of 10 days) on shoot multiplication-cum-elongation medium. The shoot multiplication rates ranged from 4 to 25-fold in CoPb 91 and CoJ 83 cultivars, respectively; Stage III involved in vitro rooting on root induction medium and hardening for 14 days at each step; Stage IV comprised separation of clumps into single plantlets and transfer to soil. The complete plants were produced in 157 days with 97 percent survival rate. The fidelity of the protocol for agri-business industry was tested by producing approximately 0.1 million saleable HTM sugarcane plants in a small scale (150 m(2)) tissue culture unit. The recurring (energy, labour, media, culture container, transplanting material) and non-recurring (laboratory infrastructure, glasshouse, equipment) parameters accounted for 75.56 and 24.44 percent production costs, respectively. The low-cost options for media, culture containers and transplanting material were incorporated and cost per plant was calculated to be US$ 0.13. The HTM protocol was adopted by two sugar mills, and the HTM plants produced in our tissue culture unit were sold for seed multiplication to eight sugar mills and 430 farmers throughout North India.