Abstract
To establish an effective cutting-based system for the propagation of Pinus thunbergii clones that are highly resistant to pine wilt disease, the productivity of rooted cuttings obtained using a closed system (in a plastic greenhouse or an open field) was compared to that of cuttings obtained using a mist system. Consequently, the rooting rate increased more rapidly in the closed system than in the mist system. Moreover, the root system of the cuttings developed faster in the closed system than in the mist system. Therefore, the survival rate of the transplanted cuttings obtained using the closed system was higher than that of the cuttings obtained using the mist system in rainy season. The rooted cuttings transplanted in the rainy season grew to a bigger size than those transplanted in the following spring. Therefore, the growth period could be shortened. However, the rooting rate of the cuttings obtained using the closed system in the open field did not increase after the 16th week of insertion. These cuttings seemed to have incurred injury owing to high temperature. Using the closed cutting system in the plastic greenhouse, the production cost of resistant plants could be reduced by approximately 10% in comparison to seedlings-based system requiring nematode artificial inoculation.
