Effects of nitrogen application methods on the growth and root development of Cinnamomum kanehirae seedlings

Objectives The quality of seedlings decides the rate of survivals during afforestation to some extent. We studied the suitable fertilization method and nitrogen fertilizer amount for the cultivation of health Cinnamomum kanehirae seedlings.

Methods A pot experiment was carried out inside green house, taking 1-year old tissue culture seedlings of Cinnamomum kanehirae as test materials. The fertilizer treatments included two conventional fertilization methods at N rate of 200 mg/plant, i.e. divided the fertilizer evenly into 2 and 10 parts for application (denoted as CF1 and CF2); and 4 exponential fertilization methods with N rate of 200, 400, 600, and 800 mg/seedling (denoted as EF200, EF400, EF600 and EF800), the N fertilizer were divided into 10 parts using classic Timmer formula; and a no fertilizer control (CK). The growth and development indexes, as well as the nutrient absorption of seedlings (aboveground part) and roots were measured after the fertilization experiment was completed.

Results Fertilization significantly improved the growth and development of seedlings. Compared with CF1 and CF2, EF200 treatment increased seedling height, ground diameter, biomass (stem and leaf), root system (length, volume, surface area, specific root length and specific root surface area), and N content of leaf, stem and root significantly. Under exponential fertilization, the biomass, and N content of leaves, stems and roots showed a trend of increase first and then decrease with the increase of N application rate, and EF400 was recorded the maximum and significantly higher values than the other treatments.

Conclusions Nitrogen application has significant effect on the growth of Cinnamomum kanehirae seedlings, using exponential method to allocate nitrogen fertilizer with the growth of Cinnamomum kanehirae seedlings could achieve higher promotion effect than the conventional method. Comprehensively considering seedling growth and nutrient accumulation, N 400 mg/seedling is recommended for the cultivating of Cinnamomum kanehirae seedlings.