Quality and production costs of seedlings grown with different root-pruning techniques

Abstract: About half of the cost of forest restoration by the framework species method (FSM) is planting stock production costs. Manual root pruning promotes better tree seedlings, but is time consuming and labor intensive. This study developed suitable nursery practices to reduce seedling production cost and to yield good quality seedlings. The study was conducted at the Forest Restoration Research Unit tree nursery in Khlong Thom district, Krabi province, Southern Thailand. Five framework tree species: Saraca indica (Fabaceae), Sandoricum koetjape (Meliaceae), Cleistocalyx operculatus (Myrtaceae), Lepisanthes rubiginosa (Sapindaceae) and Garcinia speciosa (Clusiaceae) were included. Seedling biomass after six months and production cost were compared among three different production practices; 1) seedlings in plastic crates on the ground (crate), 2) plastic crates placed on wire benches (air-pruning+crate) and 3) seedlings in plastic bags on the ground without crates (control). For C.operculatus, L.rubiginosa and G.speciosa, seedling biomass was higher with the crate and air-pruning+crate treatments compared with the control. For S.indica and S.koetjape, the crate treatments did not increase seedling biomass. Averaged across species, costs were 19.08, 20.64 and 20.15 THB per tree for the crate, air-pruning+crate treatments, and the control respectively.