Golden camellias or yellow camellias are species belonging to genus Camellia L., family Theaceae. Fifty two species were described in southern China and Vietnam. Active ingredients such as polysaccharides, polyphenols, saponins, and flavonoids are well known characteristics of golden camellias. Its leaves and flowers have been long traditionally used for health improvement. It was found to be able to inhibit transplanted cancer, lower blood pressure, lower blood lipid, lower cholesterol, and prevent atherosclerosis. Currently, it costs 320–700US$ per one kg of dry flowers. Such price attracts many local ethnic people to plant golden camellias for poverty reduction. This work reviews (1) species and natural distribution, (2) uses and healthcare values, (3) techniques for seedling production, planting and tending, and (4) opportunities and challenges for future development of golden camellias.

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Fertilizers (nitrogen/N, phosphorous/P, and potassium/K) have been widely applied to increase the productivity of forest plantation, especially in poor soils. This study was to test the effects of fertilization at planting and additional fertilization in the following two years on growth and aboveground biomass (AGB) of a 30-month old plantation of Acacia mangium in Northeast Vietnam. There were four treatments including (1) 1 kg compost/tree at planting and 0.2 kg NPK (16:16:8)/tree/year in the following two years (IC-A-NPK), (2) 1 kg compost/tree at planting and 0.2 kg P (16.5% P2O5) + 0.1 kg K (60% K2O)/tree/year in the following two years (IC-A-PK), (3) 1 kg compost + 0.2 kg NPK/tree at planting and 0.2 kg NPK/tree/year in the following two years (IM-A-NPK), and (4) 1 kg compost + 0.2 kg NPK/tree at planting and 0.6 kg P + 0.1 kg K/tree/year in the following two years (IM-A-PK). The results indicated there was no significant effect of fertilization at planting and additional fertilization on diameter at breast height (DBH), basal area, and AGB between IC-A-NPK (DBH of 8.9 cm, basal area of 7.4 m 2 ha -1 , and AGB of 37.8 Mg ha -1 ) and IM-A-NPK (DBH of 10.1 cm, basal area of 9.2 m 2 ha -1 , and AGB of 47.5 Mg ha -1 ). Meanwhile, DBH (9.6 cm), basal area (8.6 m 2 ha-1 ) and AGB (44.2 Mg ha -1 ) in IM-A-PK were significantly higher than that in IC-A-PK (DBH of 8.4 cm, basal area of 6.4 m 2 ha -1 , and AGB of 31.6 Mg h -1 ). It was concluded that fertilization at planting of both compost and NPK is not required for A. mangium plantation. While additional fertilization of phosphorus should be applied for higher productivity.

Fertilizer is applied widely to improve the productivity of plantations. Traditionally, fertilization is conducted in spring and/or in the early rainy season, and it is believed to support the growth of planted trees in the growing season. Little attention to date has been paid on identification of the optimal timing of fertilization and fertilizer dose. In this study, application of the fine root monitoring technique in identifying optimal fertilization timing for an Acacia plantation in Vietnam is described. The study used two fertilizer doses (100 and 200 g NPK/tree) and three fertilization timings (in spring; in the early rainy season; and based on the fine root monitoring technique to identify when the fine roots reach their growth peak). As expected fertilization timings significantly affected growth and above-ground biomass (AGB) of the plantation. Fertilization based on the fine root monitoring technique resulted in the highest growths and AGB, followed by fertilization in the early rainy season and then in spring. Applying fertilizer at 200 g NPK/tree based on the fine root monitoring technique increased diameter at breast height (DBH) by 16%, stem height by 8%, crown diameter (Dc) by 16%, and AGB by 40% as compared to early rainy season fertilization. Increases of 32% DBH, 23% stem height, 44% Dc, and 87% AGB were found in fertilization based on fine root monitoring technique compared to spring fertilization. This study concluded that forest growers should use the fine root monitoring technique to identify optimal fertilization timing for higher productivity.

Plus tree selection is the first step to improve production and quality in forestry. An individual-based method is widely used to select plus trees for timber production, timber form, freedom from diseases and insects. In this study, a method to select plus trees for flower production is described and named as a crown-area-based method. Both individual-based and crown-area-based methods were used to select plus trees for Camellia impressinervis, a golden camellia; its yellow flowers have been used to treat sore throat and diarrhea, and to prevent cancers in China and Vietnam. Flower production of 21 concerned individuals was compared to the population mean and it was generated as a percentage. The population mean of the individual-based method is the mean of production of 21 trees as mean production/tree. While population mean of the crown-area-based method is mean production/m2 crown area (first production/m2 crown area for each tree was generated, then mean for population). The results indicated that both methods show seven individual trees with flower production >100% population mean. However, individual trees are different. Only five of 7 trees are the same in both methods. The tree rankings by flower production percentage in both methods are totally different. The highest ranking by individual-based method (310% mean) is 4th ranking by crown-area-based method (181% mean). While the highest ranking by crown-area-based method (270% mean) is third ranking by individual-based method (260% mean). It is concluded that crown-area-based method is better in selecting plus trees for flower purpose, as it considers the crown area which is known as a productive part of a tree to form flowers.