Growth, biomass accumulation and foliar nutrient status in fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings cultured with conventional and exponential fertilizations under different photoperiod regimes

Abstract

In this study, fragrant rosewood (Dalbergia odorifera T.C. Chen) seedlings were cultured with conventional and exponential fertilization treatments at rates of 2 and 4 g plant −1 (15-9-12), and an unfertilized control under the natural photoperiod and extended photoperiods with supplementary lighting for 3 and 6 h. Seedlings under the extended photoperiods had greater height but less root-collar diameter than those under the natural photoperiod. The extended photoperiod with supplementary lighting for 3 h resulted in the greatest biomass in stem and root. Apparent nutrient dilution was found from October 2015 to January 2016 in most fertilization treatments, which, however, was counted by the treatment of exponential fertilization at 4 g plant −1. Vector analysis indicated that the treatment of extended photoperiod with supplementary lighting for 3 h induced nutrition depletion for nitrogen (N) and phosphorus (P) relative to the natural photoperiod, while the exponential fertilization treatment induced luxury consumption for all elements of N, P and potassium (K) relative to the control. In conclusion, the extended photoperiod of supplementary lighting for 3 h was recommended for the culture of fragrant rosewood seedlings, and the exponential fertilization resulted in better nutritional status by counting nutrient dilution relative to the conventional fertilization.

Nutrient Uptake and Utilization by Fragrant Rosewood (Dalbergia odorifera) Seedlings Cultured with Oligosaccharide Addition under Different Lighting Spectra

“…This fertilizer regime has been proven to promote the growth and nutrient utilization in Fragrant rosewood [7]. All seedlings shared the same fertilization regime.…”

“…Artificial devices were open from 6:00 a.m. to 21:00 p.m., generating a 15 h photoperiod for daily seedling growth. This photoperiod included about three hours of supplemental lighting during night time, which has been proven to favor the growth and nutrient utilization in Fragrant rosewood [7]. The adjacent two main-blocks receiving different light spectra treatments were separated by a black-out cloth fixed at 1.2 m from the ground.…”

“…Fragrant rosewood was categorized as vulnerable by World Conservation Monitoring Centre (WCMC) [35]. However, recently, the over-development has driven the natural source of this species to be nearly exhausted, which has promoted this species to be classified as a second-grade state-protected tree by the Chinese government [7]. Meanwhile, the demand for high-quality seedlings of Fragrant rosewood in southern areas of China is always increasing for its forest establishment during urbanization.…”

“…As the common rule suggests, short-lived native trees with a higher growing rate should dominate initially with slower growing species colonizing and establishing during later successional stages [4]. Some slowly-growing species, however, are heavily preferred to dominate the urban landscape due to their high commercial values [5][6][7][8][9] and contribution to perceived well-being [10,11]. The increasing demand for slow-growing trees has threatened the natural source because the artificial culture usually requires several years, as well as considerable expenses in labor, land, and power.…”

“…Chen) is a perennial legume tree distributed in sub-tropical and tropical areas of China, but its heartwood is popularly taken as a traditional herbal medicine in North East Asia [7]. Fragrant rosewood was categorized as vulnerable by World Conservation Monitoring Centre (WCMC) [35].…”