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Abstract
Aims: Apply different silvicultural approaches to improve oil productivity and quality from abandoned stands and analyze cost-benefit of developing tea oil camellias. Study Design: Three experiments were conducted as (1) Changing canopy of 36-year-old plantation by grafting, (2) Using Bortrac fertilizer for promoting fruiting by spraying to canopy, and (3) Stem/branch thinning and fertilizing. Place: North Central, Vietnam at 19º16’N and 105º23’E. Methodology: Shoots of 4 – 6 mm in diameter and 3 -5 cm long from improved cultivar were used to graft to 36-year-old trees. Bortrac fertilizer was used to spray to canopy of 15-year-old plantation when trees bloomed. While three treatments of stem/branch thinning and fertilizing at different intensities was applied to 29-year-old plantation of 830 trees ha-1. Results: The results showed that old stand, which has low seed productivity, could be replaced by a new canopy through grafting with improved cultivars. Meanwhile, fertilizing through spraying on canopy at early blooming peak with Bortrac fertilizer increased seed productivity by 28%. In addition, applying 0.5 kg inorganic fertilizer (NPK) and 5 kg organic manure per tree coupled with thinning under crown-old branches and diseased branches increased up to 60% seed productivity and improved oil ratio and quality. Cost-benefit analysis indicated that by applying different intensities of stem/branch thinning and fertilizing to 29-year-old plantation, profit margin increased from US$ 502 to as much as US$ 549 ha-1 year-1 for growers selling dry seeds as final product. Meanwhile, it increased from US$ 1,791 to US$ 2,426 ha-1 year-1 by extracting oil for final product. Conclusion: There is a potentiality of growing tea oil camellia with the increased profit of as much as US$ 2,426 ha-1 year-1 for 29-year-old plantation by applying intensive silvicultural approach.