Influence of light quality and some growth regulators on in vitro shoot proliferation and rooting of pear rootstock OH×F333

This research was aimed to investgate the effect of light quality on micropropagation of pear rootstock OH×F333. First, single nodes explants were cultured in modified QL medium containing BA at four levels (0, 0.5, 1, and 2 mg/l-1) and IAA at three levels (0, 0.1, and 1 mg/l-1) and were evaluated for shoot proliferation. Then, plantlets subcultured in modified QL medium containing 1 mg/l-1 BA and were maintained in growth chamber under four level of light quality consisting red, blue and red-blue light provided by LED instrument and white cool light provided by florescent, all having 75 µmol m-2 s-1 intensity. For investigation of light quality on rooting, shoots were subcultured on modified QL medium containing 1 mg/l-1 IAA and were incubated under same light treatments. The results indicated that the highest number of proliferated shoots was obtained in red-blue light while the longest shoots and internodes was in red light treatment. Moreover, the number of leaves and nodes of plantlets grown under blue light were high. Light quality showed significant effect on rooting percentage, root number and root length. The highest rooting, with 100 percent rooting of shoots, was observed in red-blue light treatment. In contrary, the lowest percentage of rooting, the lowest number of root and the shortest length of root were observed in blue light treatment. Based on current results, combination of blue and red light in comparison to other light treatment was more appropriate treatment for shoot proliferation and rooting of pear rootstock OH×F333. The explants under this treatment showed higher number of shoots.