Coupling Effects Of Water And Nitrogen On Biomass Yeild And Quality In Switchgrass And Reed Canarygrass

Due to the environmental friendly, strong adaptability and high yield characteristics,Switchgrass （Panicum virgatum L.） and reed canarygrass （Phalaris arundinacea L.） wereidentified as new energy plants. In order to the success of the large-scale cultivation of thetwo speices, there is a need to investigate coupling effects of water and nitrogen fertilizationon biomass yield and quality of switchgrass and reed canarygrass. The experiments wereorthogonally designed to incorporate two factors at five levels using orthogonal matrix, a totalof22treatments,3replicates per treatment. The soil water content （X₁） has five levels forboth species:32%,24%,20%,16%,8%. Nitrogen （X2） has five levels for switchgrass:0.072g （=10kg/hm²）,0.792g （=110kg/hm²）,1.152g （=160kg/hm²）,1.512g （=210kg/hm²）,2.232g （kg/hm²=310）; Five nitrogen levels for reed canary grass:0.072g （=10kg/hm²）,1.080G （=150kg/hm²）,1.584g （=220kg/hm²）,2.008g （=290kg/hm²）,3.096g （=430kg/hm²）. Control soil moisture by the method of weight. After8weeks’ treatment,cropping, measuring indexes.The results of experiments are as follows:1)For the biomass production, the effects of water and fertilizer interaction on the drymatter yield and quality in switchgrass and reed canarygrass were variable. The biomassregression model for switchgrass and reed canarygrass were:Y=28.622+2.514X₁+4.275X₂+0.816X₁X₂-0.554X₁²-0.765X₁²Y=14.4170.801X₁+1.860X₂+0.217X₁X₂-0.402X₁²-0.226X₂²Where X₁is the code of nitrogen concentration, X2is the code of soil water content.2) Plant height and tiller of the two speices increased quickly within a few weeks afterapplication of N fertilizer. Plant height of switchgrass was influenced by the interactions ofnitrogen and water. Plant height of reed canary grass was not affected by nitrogenconcentration, that is，plant height did not change significantly under the situation of differentN fertilizer treatments. When the soil moisture content is above16%and nitrogenconcentration is above0.792g/pot, switchgrass tillering numbers no longer increased. Withthe increase of nitrogen concentration and soil water content, tillers of reed canarygrass raised firstly, then decreased.3) Cellulose and hemicellulose content of switchgrass change significantly underdifferent treatments. Cellulose and hemicellulose content increased with the increase ofnitrogen fertilizer, and decreased with the increase of soil water content. Cellulose andhemicellulose content of reed canarygrass peak at the treatment of the lowest nitrogenconcentration and lowest soil water content. Lignin content of switchgrass increased with thedecrease of nitrogen concentration, increased with the increase of soil water content. But ashcontent of reed canarygrass was not significant difference （P <0.05） under various treatments,and ash content was maximal in the treatment of lowest nitrogen concentration and lowest soilwater content.4) Soluble sugar content of switchgrass increased with the increase of nitrogen fertilizer,decreased with the increase of soil water content. When the soil moisture content is>8%,soluble sugar content of reed canary grass increased with the decrease of soil water content.Chlorophyll content of two species were unaffected by soil moisture content, but affected bynitrogen concentration, its content increased with the increase of nitrogen concentration, andsignificantly difference among various treatments （P <0.05）.5) When nitrogen concentration is above1.152g/pot, nitrogen absorption and nitrogenuse efficiency of switchgrass were significantly low, as for reed canary grass the nitrogenconcentration is1.584g/pot. This suggest that more nitrogen is unhelpful for biofuel.