Development of a novel in vitro rooting culture system for the micropropagation of highbush blueberry (Vaccinium corymbosum) seedlings

Key message We established a novel, efficient, and cost-effective rooting culture system for the micro-propagation of highbush blueberry seedlings that overcomes many of the drawbacks of traditional methods of industrial rooting. Here, we established a novel, efficient, and cost-effective rooting culture system for highbush blueberry (Vaccinium corymbosum). This method overcomes the inefficient, expensive, and time-consuming nature of traditional methods and provides a theoretical basis for the industrial rooting of micropropagated blueberry seedlings. Semisolid half-strength woody plant medium (1/2WPM), supplemented with carrageenan as fixing material, was packed into high molecular polypropylene plastic bags. Optimum response of 'Ozarkblue' was observed in 1/2WPM supplemented with 0.1 mg/l indole-3-butyric acid (IBA); 97.7% rooting rate was achieved at 45 days after culture, with the average root number and length reaching 6.5 +/- 0.39 and 3.5 +/- 0.16 cm, respectively. The highest rooting rate of 'Weiwa Kuahuat' (84.0%) was achieved with 0.5 mg/l IBA, resulting in a favorable average root number (3.0 +/- 0.43) and length (3.0 +/- 0.43 cm). 'Sierra' showed the highest rooting rate (100.0%) in the presence of 1.0 mg/l IBA, with an average root number and length of 5.9 +/- 0.9 and 3.9 +/- 0.62 cm, respectively. The earliest and fastest rooting was recorded when shoots were transplanted into bags for 13 days. A space utilization experiment showed that the density of well-grown blueberry seedlings achieved in bags (1600 seedlings/m(2)) was superior to that obtained using traditional in vitro and ex vitro rooting methods (270 and 420 seedlings/m(2), respectively). This is the first report of a complete rooting system that could serve as a feasible blueberry rooting method with superior rooting time, rooting rate, medium consumption, space requirement, and portability.