Optimum Nitrogen Fertilization for Phyllostachys edulis Productivity and Photosynthetic Response

Nitrogen fertilizer is supplied for high production of Phyllostachys edulis (Carriere) J. Houz. shoots and culms. Th e objects of this study were to determine the optimum fertilizer amount, determine the eff ects of N fertilization on the promotion of photosynthesis, and provide help for remote sensing of fertilization eff ects. Th e shoot and culm production was signifi cantly increased with 100, 250, and 400 kg N ha(1), and the two latter fertilization levels showed the best promoting eff ects without signifi cant diff erence between them. Under N fertilization, the photosynthetic pigment content was increased, which led to a decline in the refl ectance spectra. Nitrogen fertilization promoted quantum production and electron transport in photosystem II and inhibited the dissipation of absorbed light energy. Th e absorbed light energy can be emitted as fl uorescence, which showed two main peaks in the red (685 nm) and far-red (735 nm) regions. Th e width and area of the fl uorescence peak at 735 nm declined, suggesting that N fertilization promoted the transduction of absorbed light energy in photosystem I. A remarkable reduction in intercellular CO2 concentrations and the light compensation point and an increase in the light saturation point demonstrated that the CO2 assimilation ability was increased with N supplementation. Among the three fertilization levels, 250 kg N ha(1) had the best eff ect on photosynthesis. We concluded that 250 kg N ha(1) is more suitable for practical application. Th e refl ectance indexes and refl ectance intensity ratio F685/F735 were signifi cantly changed with N fertilization, indicating that they have potential value for estimating fertilization eff ects on bamboo production.