| Abstrakt: |
Vetiver grass (Chrysopogon zizanioides) is a warm season perennial grass grown as a phytoremediation tool and recently proposed as a plant material source for biofuel production. However, limited information exists on Vetiver grass fertility management practices in cropping systems. Therefore, the effects of nitrogen (N) level and N-form on Vetiver growth and development were investigated. Plant slips of C. zizanioides Sunshine were greenhouse-grown using nutrient solution culture. In the first experiment, N-level treatments were 26.3, 52.5, 105, 210 and 410 mg N⋅L-1 at a ratio of 3:1 nitrate-N: ammonium-N. In a second experiment, the ratio of NH4:NO3 was changed from 0:100, 25:75, 50:50, 75:25, and 100:0 while keeping a total N level of 210 mg N⋅L-1. At 12 weeks after transplanting (WAT), plant height, tiller number, accumulated shoot, root, and total fresh weights and dry weights, total leaf number, and chlorophyll content were recorded. Leaf number decreased linearly (P≤0.10) from 11.2 per plant at 26.3 mg N⋅L-1 to 9.7 per plant at 210 mg N⋅L-1 while leaf chlorophyll content increased, then decreased quadratically (P≤0.10) over the same N level treatment range. Shoot dry weight and total plant dry weight increased, then decreased (P≤0.10, respectively) as N level was increased in nutrient solution. In the second experiment, plant height decreased linearly (P≤0.05) from a mean of 100.9 cm per plant at 1:100 NH4:NO3 ratio to 90.5 cm per plant at 100:1 NH4:NO3 ratio treatment. Linear increases were observed for tiller number (P≤0.10) and leaf number (P≤0.001) per plant as the ratio of NH4:NO3 was changed from 1:100 to 100:0. Limited effects of form were identified for plant biomass parameters. Results demonstrate that Vetiver grass may successfully be cultured under lower N fertility and has a tolerance to ammonium-N in managed cropping systems. [ABSTRACT FROM AUTHOR] |
