Impact of Synthetic Nitrogen Rates on Fresh and Dry Weight Biomass Yield, Above-ground Plant Components, Physiological Parameters of Three Perennial Feedstock Bio-fuel Grass Species

The objective of this study was to evaluate how inorganic nitrogen fertilization rates effect fresh and dry weight yields (FWY and DWY), above ground plant components, photosynthesis (Pn), transpiration (E),conductance (C) and leaf area index (LAI) of perennial bio-fuel grass species giant reed (C1), napier grass (C2) and energy cane (C3). The nitrogen rates [zero N=0N(no nitrogen), half N=HN(100 kg of N/ha) and full N=FN(200 kg/ha)] were applied to grass species using randomized complete block design with four replications as follows: 1) C1- 0N, 2) C2-0N, 3) C3-0N 4) C1-HN, 5) C2-HN, 6) C3-HN, 7) C1-FN, 8) C2-FN, and 9) C3-FN. Significant (P=0.05) differences occurred among treatments for FWY, DWY, stalk no./ha, culm fresh wt., stalk no./culm, stalk ht./culm, fresh wt./stalk and LAI. Treatment C2-0N produced highest FWY and DWY (238.1and 60.5 Mg/ha) while lowest FWY and DWY by C3-HN (58.4 and 15.6 Mg/ha respectively). Treatment C2-0N produced maximum (481793) stalk no./ha with C3 at HN producing minimum stalk no./ha (211969). Treatments C2-0N produced highest culm fresh wt. (14.94 kg) and stalk no./culm (30.2) while lowest culm fresh wt. (3.67 kg) and stalk no./culm (13.30) was produced by C3-HN. C1-HN produced highest stalk ht./culm (356.7 cm) were by and C3-HN produced the east (171.0 cm). Maximum fresh wt. / stalk (489.1 g) was produced by C2-0N with C1-0N producing minimum (217.4 g) fresh wt. per stalk. Leaf Area Index was highest (5.2) for C2at FN and lowest (2.5) for C3-0N. Physiological parameters were examined with C2-FN, C1-HN and C1-FN producing highest Pn (19.6 umol/m²/s), E (2.7 mmol/m²/s) and C (388.0 mmol/m²/s). The results indicated that napier grass performed better than energy cane and giant reed with 0 nitrogen rate predominating for yield and above ground plant components while LAI and physiological parameters were effected the most by napier grass at full nitrogen. Further research is needed before conclusive recommendations are provided.