Growth and N accumulation in seedlings of Cunninghamia lanceolata clones with N exponential fertilization

Abstract

High quality cloned seedlings of Chinese fir (Cunninghamia lanceolata), a fast-growing China-specific plant species dominant in south China, play an important role in Chinese fir forestation. To understand the effects of N exponential fertilization on seedling growth and nutrient content of Chinese fir, pot experiments were conducted in a greenhouse. One-year-old cloned seedlings were used with five N treatments per seedling including no fertilizer (ck) (0 g), conventional fertilization (CF) (0.5 g), and exponential fertilizations of EF1 (0.5 g), EF2 (1.0 g), and EF3 (2.0 g). Replications N fertilization was conducted 20 times at 10 d intervals. Height, ground diameter, biomass, and N absorption were measured after seedling growth. Analyses included state the sampling method and size. Results showed that fertilization of Chinese fir clones significantly promoted seedling height, ground diameter, and biomass (P roots > stems. Compared with ck, for conventional fertilization groups the N concentration increased in roots 39.6%, stems 16.6%, and leaves 41.1% with N content increasing 90.5% in roots, 119.5% in stems, and 267.2% in leaves; and for exponential fertilization groups the N concentration increased 22.6%-81.4% in roots, 27.3%-152.6% in stems, and 73.6%-135.5% in leaves with N content increasing 70.8%-138.8% in roots, 145.7%-355.8% in stems, and 347.6%-561.7% in leaves. Thus, N application rate had strong effect on growth of Chinese fir with the best method for cultivating Chinese fir cloned seedlings, considering seedling growth, N concentration, and N accumulation, being exponential N of 1 g·seedling-1.