Effect Of Planting Density And Cutting Frequency On Feed , Energy And Carbon Sequestration Value In Pennisetum Americanum × P. Purpureum

Pennisetum americanum×P.purpureum is a hybrid of Pnnisetmeamerieanum and P.purpureum. That integrated the characteristics of high yield, perennial and high quality,and which was widely cultivated in recent years. The effects of the panting density and the cutting frequency on growth characteristics, high yield, feed quality,energy utilization and power of fixing carbon in Pennisetum americanum×P. purpureum planted in field under certain ecological conditions were studied in this paper, in which 3 plant densities and 3 cutting frequencies were designed, and this research was conducted in Handan city, Hanbei Province from April to November in 2009. The results showed that:1.Under the density of 13889/hm², yield and stem leaf ratio was the highest. The yield in cutting twice a year was the highest.The yield in cutting six a year was the lowest yet its quality was the best,while the quality in cutting twice a year ranked the last.It also had a lower Stem Leaf Ratio and a higher Fresh Dry Weight ratio which led to better palatability.Highest green leaves yield of 198.10 t/hm² was as density of 13889/hm² and cut twice a year defoliation interval.General analysis showed that plant density and cutting frequency of Pennisetum americanum×P.purpureum increasing to 13889/hm² and cut four a year has the best yield.2.The crude protein (%) decreased with the increasing density,and increased with the increasing of defoliation frequency. Best crude protein(%) were as density of 27778/hm² and cut six a year. Viewed from cutting frequency effect on dynamic quality change, the crude protein (%) decreased with the increasing density;DNF and ADF(%) increased with the increasing density;Ash(%) decreased with the increasing density.Followed the cutting frequency increasing,the crude protein (%) and ash(%) decreased, but NDF and ADF increased. General analysis showed that plant density and cutting frequency of Pennisetum americanum×P.purpureum increasing to 6944/hm² and first cutting has the best quality.3.Under the density of 13889/hm², dry yield was the highest;under the density of 6944/hm², Gross Caloric values and Ash free caloic values was the highest;under the 13889/hm² the two caloic yield was the highest; ash(%) change was invisible.NDF change was invisible and ADF increased with the increasing density. Followed the cutting frequency decreased,the dry yield decreased.Followed the cutting frequency increasing Gross Caloric values and Ash free caloic values decreased;the two caloic yield decreased with the cutting frequency increasing. Ash(%)decreased with the cutting frequency increasing. DNF and ADF(%) decreased with the increasing cutting frequency. Highest dry yield of 32.48t/hm² was as density of 13889/hm² and cut twice a year defoliation interval. Highest Gross Caloric values and Ash free caloic values was as density was 6944/hm² and cut twice a year defoliation interval. Highest the two caloic yield was as density was 13889/hm² and cut twice a year defoliation interval.Best ash content was 13889/hm² and cut four a year defoliation interval. Highest NDF and ADF was as density was 13889/hm² and cut twice a year defoliation interval.4.Under the density of 13889/hm², CO₂ fixed was the highest;plant mothod has greatest impact on 0-10cm soil. Under the influence of the density, organic carbon DIFF increased with the density increasing. Photosynthetic rate increased with the density increasing.Plant carbon content decreased with the density increasing.carbon yield decreased with the density increasing. Under the influence of the cutting frequency, CO₂ fixed decreased with the cutting frequency increasing. 0-10cm soil organic carbon DIFF increased with the cutting frequency increasing. Photosynthetic rate increased with the cutting frequency increasing. Plant carbon content and carbon yield decreased with the cutting frequency increasing.Highest CO₂ fixed was as density was 13889/hm² and cut twice a year defoliation interval. Highest 0-10cm soil organic carbon DIFF was as density was 6944/hm² and cut six a year defoliation interval. Highest photosynthetic rate was 6944/hm² and cut twice a year defoliation interval. Highest Plant carbon content was as density was 6944/hm² and cut six a year defoliation interval, and carbon yield was as density was 13889/hm² and cut twice a year defoliation interval.