Efficient microtuber production of potato in modified nutrient spray bioreactor system

Abstract

A laboratory scale bioreactor system has been developed using nutrient spray technology for in vitro mass production of potato microtubers. Its effectiveness on the production of microtubers was investigated and compared with conventional liquid and semi-solid culture systems through bioreactor. Optimal culture conditions such as spray intervals, varying concentrations of 6-benzylaminopurine (BAP) and explants density were determined for the NSB. In order to determine optimal spray intervals, liquid medium was sprayed inside the NSB at different intervals (½, 1–4h) of which the 1h interval resulted in the highest number of shoots (3.47) and length (8.99cm). Number of microtubers produced (5.13) was highest with 1h intervals and fresh weight of microtubers (0.90g) was highest for ½h interval. Different concentrations of BAP (0.5, 1.0 and 1.5mg/L) were used to evaluate its effect on microtuberization. It was observed that number and diameter of microtubers were increased (5.31 and 0.96cm) when 0.5mg/L BAP was supplemented in MS medium. We found fresh weight of microtubers (0.97g) was increased when 1.0mg/L BAP were added to the medium. In order to determine suitable explants density, single nodes grouped into five categories e.g 30, 45, 60, 75, and 90 and placed in the NSB system. A density of 60 explants resulted in increases in shoot length (17.5cm) number of internodes (12.5) and with highest amount of chlorophyll (40.2mg/g) as well as with highest number and fresh weight of microtubers (4.43 and 0.89g, respectively). Out of the three culture systems, the NSB performed best where 1.5–2.0 fold increases in shoot growth and microtuberization without hyperhydration. The NSB also produced the highest number (4.67), fresh weight (0.86g) and diameter (0.78cm) of microtubers. From this study we may conclude that the NSB system has good potential for commercial mass production of potato micro-tuber.