Effect of nitrogen fertilizer application on growth, biomass production and N-uptake of torpedograss (Panicum repens L.) |
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| Authors: | MOHAMMAD AMZAD HOSSAIN YUKIO ISHIMINE HIKARU AKAMINE HITOSHI KURAMOCHI |
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| Institution: | Faculty of Agriculture, University of the Ryukyus, Okinawa and; Center for Research on Wild Plants, Utsunomiya University, Utsunomiya, Japan |
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| Abstract: | A glasshouse study was conducted to evaluate the effects of different rates (0, 50, 100, 200 and 400 kg ha?1) of nitrogen (N) fertilizer application on the growth, biomass production and N‐uptake efficiency of torpedograss. The growth responses of torpedograss to the N application were significant throughout the observation periods. Torpedograss grown for 60 days obtained the highest total biomass of 23.0 g plant?1 with an application of 200 kg ha?1 N, followed by 20.4 g plant?1 with an application of 100 kg ha?1 N; when it was grown for 90 days a significantly higher biomass of 102.3–106.0 g plant?1 was obtained with the 200–400 kg ha?1 N than the biomass (68.0 g plant?1) obtained with the fertilizer applied at a lower rate. When the torpedograss was grown for 130 days the highest biomass was 230.0 g plant?1 with the 400 kg ha?1 N application, followed by a biomass of 150.0 g plant?1 with the 200 kg ha?1 N application, but the above‐ground shoot in all treatments was over mature for animal food. The ratio of the above‐ground shoot to the underground part increased with the increase in N application up to 400 kg ha?1 during the 90 days after planting (DAP), but the above‐ground shoot biomass was the same with the 200 and 400 kg ha?1 N. The agronomic efficiency of the N application decreased to 5–38 with the increase in N application to 400 kg ha?1, which was less than half the agronomic efficiency with the 200 kg ha?1 N. The agronomic efficiency of N was very low (5–22) during the 60 DAP, which indicated that the N application would not be economically viable in this period for torpedograss as a pasture, and short‐duration plants could be cultivated in torpedograss‐infested fields to minimize weed‐crop competition. The nitrogen concentration (%) in the torpedograss increased with the increase in N application, but N‐uptake efficiency was the opposite and the value was very low with the 400 kg ha?1 N. The above results lead us to conclude that the N application rate of 200 kg ha?1 is the most effective for torpedograss growth. |
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| Keywords: | biomass production growth stage N-fertilizer Panicum repens L |
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