Establishment of a Propagation System for Strawberry Using a Plant Factory with Artificial Lighting

Abstract

This thesis consists of four chapters of foundation research to establish an autotrophic transplant production method (ATPM), a novel propagation method for strawberry using a plant factory with artificial lighting for transplant production (T-PFAL). In ATPM, it was necessary to use smaller runner plants as propagules than mother plants in conventional propagation mehtods in order to reduce the timescale for production of new propagules and to enhance propagation rates. To maximize propagation rate in ATPM, the appropriate size of propagules was determined. As the net photosynthetic rate of runner plants after separating did not decrease beyond 15 days after fixing runner tips (DAFR), they were grown autotrophically after 15 DAFR when their crown diameter was c.a. 4.6 mm. Propagation cycles (required timescale to produce new propagules) and productivity of propagules with a 5 mm crown were shorter and greater, respectively, than those of propagules with a 4 mm crown or a 6 mm crown. These results indicate that appropriate propagules for ATPM are runner plants with a 5 mm crown, two leaves, and a runner. In the T-PFAL, the runner plants connected with their propagules should be grown under high density and smaller container volume to increase the space efficiency as they were grown dependency on their propagules. Using nine propagules with two leaves, a runner, and a 5 mm crown by ATPM in a cultivation area of 3.6 m2 for 365 days, we produced 3,497 strawberry transplants, which was 15 times greater than that from conventional propagation methods. Through a program for estimation of strawberry transplant production for the propagation system verified by measured results, we assured that the ATPM is an appropriate propagation method to produce transplants rapidly in a T-PFAL, which would be especially, useful when the number of propagules or propagules is limited. We established ATPM to produce strawberry transplants using smaller propagules in a T-PFAL through these researches and expected that using ATPM at upper step in the propagation and distribution system for domestic strawberry cultivars will be able to spread new cultivars quickly.