收获时间对黄土高原柳枝稷生物质产量与燃料品质的影响

为探明黄土高原半干旱地区柳枝稷生物质产量和燃料品质随收获时间的变化规律,确定适宜的收获时间,在甘肃省庆阳市进行田间试验,研究收获时间对柳枝稷生物质产量与燃料品质的影响。结果表明：1）随收获时间的推迟,柳枝稷生物质产量呈下降趋势,且叶片所占比例逐渐降低,说明产量损失主要是叶片脱落。2）柳枝稷生物质热值总体上呈降低趋势,开花期热值显著高于其他时期;延迟收获显著降低了柳枝稷生物质含水量和灰分含量;随收获时间推迟,柳枝稷茎叶纤维素、木质素含量提高,半纤维素含量降低;枯亡期之后柳枝稷生物质中K、Mg、Na、Cl等不利于燃烧的矿质元素含量显著降低,生物质的燃料品质提高。3）在柳枝稷能源生产模式下,生育季节末期柳枝稷地上部衰亡后收获生物质燃料品质较好。

Effect of harvesting periods on biomass yield and fuel quality of switchgrass in the Loess Plateau of China

The objective of this experiment is to evaluate the variation in yield and fuel quality of switchgrass biomass under different harvesting periods and to determine appropriate harvesting periods.Field trials were conducted in Qingyang,Gansu Province,to evaluate biomass yield and fuel quality of switchgrass under different harvesting time in order to determine the proper harvesting time.The results were as follows:1) with the delayed harvesting period,yield of switchgrass presented downtrend,and the proportion of leaves reduced gradually.It indicated that yield loss was mainly due to leaf abscission.2) The heat value of switchgrass biomass showed a decreasing tendency as a whole,it was significantly higher at the flowering stage than other periods; delayed harvest significantly reduced moisture and ash content of switchgrass biomass; with the delayed harvesting period,cellulose and lignin content in stems and leaves increased,while hemicelluloses content decreased; undesirable components of mineral element such as K,Mg,Na,Cl were significantly reduced after switchgrass withered,and the fuel quality of switchgrass biomass improved.3) In the pattern of energy production of switchgrass,switchgrass biomass fuel quality was better when harvested at the end of growth season,after the decline of above-ground parts.