Effects of density and fertilization on growth and biomass characteristics of newly grown Dendrocalamus sinicus

  Objective  The effects of cutting-remaining bamboo density and organic fertilizer amount on newly grown bamboo growth, biomass accumulation and distribution characteristics of Dendrocalamus sinicus were explored, providing a basis for the cultivation and management of D. sinicus.

  Method  A two-factor and four-level orthogonal experiment was designed (cutting-remaining bamboo density: 7, 15, 25, 35 tree/cluster. organic fertilizer amount: 0, 40, 80, 120 kg/cluster) and 23 indexes of young D. sinicus growth and biomass characteristics were measurand for evaluating the density and ferilization effects of 16 types of experimental treatment combinations by variance analysis, principal component analysis and weighting-fuzzy mathematics in southwestern Yunnan Province of southwestern China.

  Result  (1) On average, young bamboo amount: 1.0−7.8 tree/cluster, DBH: 17.2−19.9 cm, total length: 29.0−29.9 m, clear length: 14.8−16.3 m; biomass of each component of individual newly grown bamboo: total biomass each tree: 69.63−98.13 kg, aboveground biomass: 58.22−80.42 kg, underground biomass: 11.41−17.71 kg, stalk biomass: 48.94−60.37 kg, branch biomass: 3.71−12.04 kg, leaf biomass: 1.55−9.10 kg; biomass of each component of newly grown individual bamboo cluster: total biomass: 69.63−678.20 kg, aboveground biomass: 58.22−543.62 kg, underground biomass: 11.41−134.58 kg, stalk biomass: 48.94−467.89 kg, branch biomass: 5.69−48.04 kg, leaf biomass: 3.60−28.69 kg; proportion of biomass allocation of components of newly grown bamboo: aboveground biomass:79.47%−83.62%, underground biomass: 16.38%−20.53%, stalk biomass: 60.41%−74.87%, branch biomass: 5.12%−12.27%, leaf biomass: 2.11%−9.26%, root-shoot ratio: 0.20−0.26, leafing intensity: 0.40−0.75. (2) The effects of cutting-remaining bamboo density and organic fertilizer amount on bamboo growth and biomass characteristics of D. sinicus were significant. At the same cutting-remaining bamboo density and as the organic fertilizer amount increased, the indexes of young D. sinicus growth and biomass were increased, the biomass distribution proportions of underground, branch and leaf were increased and the biomass distribution proportions of aboveground and stalk were decreased. At the same organic fertilizer amount and as the cutting-remaining bamboo density increased, the indexes of young D. sinicus growth and biomass were increased firstly and then decreased (peak turning point: 25, 15 tree/cluster), the biomass distribution proportions of underground and stalk were increased, while the biomass distribution proportions of aboveground, branch and leaf were decreased. (3) The growth and biomass characteristics of D. sinicus biomass under different experiment treatments were evaluated. Stalk-comprehensive score (the first three): T₄^{(7 + 120)} (0.457), T₈^{(15 + 120)} (0.390), T₃^{(7 + 80)} (0.389). Cluster-comprehensive score (the first three): T₁₂^{(25 + 120)} (0.456), T₈^{(15 + 120)} (0.447), T₄^{(7 + 120)} (0.424).

  Conclusion  The cutting-remaining bamboo density is 25 tree/cluster and the organic fertilizer amount is 120 kg/cluster, which are helpful to facilitate bamboo growth and raise productivity of D. sinicus.