Thailand rosewood (Dalbergia cochinchinensis)is a vulnerable high value tree species in subtropical and tropical Southeast Asia.The demand for the rehabilitation of the natural habitat of the species requires high-quality seed-lings.However,current fertilizer regimes tend to deliver a coarse rate of fertilizers that result in a low uptake efficiency and a high risk of nutrient excess.Exponential fertilization is an effective approach to promote seedling quality through identifying an optimum dose out of a range of applications.In this study,Thailand rosewood seedlings were cultured in a mixed substrate of perlite,vermiculite,and peat (2∶2∶3,v/v/v) and received exponential fertilization from 0 (con-trol),through 100,200,300,400,and 600 mg nitrogen(N) per plant over a four-month cultural rotation.Height,diameter,and shoot biomass increased with fertilizer rate and were maximized at 300 mg N per plant.This applica-tion also reduced nutrient deficiencies and avoided excess supply compared to higher rates.Polysaccharide,proline,and anti-oxidation enzyme activities tended to be greater in unfertilized controls or in over-fertilized high dosages,with lower activities around 100-300 mg N plant-1.Appli-cation of 300 mg N per plant was identified as the optimum dosage as it maximized nutrient reserves,polysaccharide and proline contents,and anti-oxidants without causing any symptoms from excess fertilizer toxicity.Future work is required to identify the effects of N-fixation on the forma-tion of nutritional reserves in Thailand rosewood seedlings subjected to exponential fertilization.

Zhou Hong;Junyu Guo;Ningnan Zhang;Zengjiang Yang;Xiaojing Liu;Zhiyi Cui;Daping Xu

State Key Laboratory of Tree Genetics and Breeding,Research Institute of Tropical Forestry,Chinese Academy of Forestry,Guangzhou 510520,People's Republic of China

林业研究（英文版）

[1]Zhou Hong;Junyu Guo;Ningnan Zhang;Zengjiang Yang;Xiaojing Liu;Zhiyi Cui;Daping Xu-.Polysaccharide,proline,and anti-oxidation enzyme activities of Thailand rosewood (Dalbergia cochinchinensis) seedlings exposed to exponential fertilization)[J].林业研究（英文版）,2022(01):75-87

rosewood,lings,perlite,unfertilized,Appli

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