氮肥种类及施氮水平对桂牧一号杂交象草体外发酵特性的影响

Effects of different kinds and levels of N fertilizer on in vitro fermentation characteristics of hybrid napiergrass Guimu-1

为更好地指导桂牧一号杂交象草的优质高产栽培,设7个处理,分别为：A1（施尿素,150 kg/hm^2）,A2（施尿素,300 kg/hm^2）,A3（施尿素,450 kg/hm^2）,B1（施碳铵,411.3 kg/hm^2）,B2（施碳铵,821.4 kg/hm^2）,B3（施碳铵,1 231.65 kg/hm^2）,CK（不施氮肥）,用体外产气法测定了不同氮肥及施氮水平下桂牧一号杂交象草的产气量以及干物质和有机物的体外消失率.结果表明：各处理组牧草间产气动力学参数差异显著（P〈0.05）,理论最大产气量、产气速率常数、产气延滞时间和干物质体外消化率分别以处理B1,B1,A3和B1最高,而以处理A1,A1,B2和B3最低.相关性分析表明,理论最大产气量与产气速率呈显著正相关,干物质、有机物体外消失率与中性洗涤纤维含量呈显著正相关,干物质体外消化率与牧草中磷含量呈显著负相关,产气速率与延滞时间之间的相关不显著,其他各参数与营养成分之间的相关性较低.从桂牧一号杂交象草体外发酵的特性来看,施用碳铵要优于尿素,碳铵的施用量以411-821 kg/hm^2较为适宜.

An experiment was conducted to seek guidance for high quality and yield of Hybrid napiergrass ＂Guimu-1＂, using an improved in vitro gas production technique. It was divided into 7 groups： At（urea 150 kg/hm^2）, A2（urea 300 kg/hm^2）, A3（urea 450 kg/hm^2）, Bt（anunonium carbonate 411.3 kg/hm^2）, B2（anunonium carbonate 821.4 kg/hm^2）, B3（anunonium carbonate 1 231.65 kg/hm^2）, CK（contrast group）. The modeling Gompertz in vitro fermentation kinetic parameters： total gas production （GP）, maximum theoretical gas production（A）, gas production rate constant （be） and lag time （LAG） were obtained by using nonlinear regressive procedures. The coefficients between kinetic parameters and different chemical compositions were analyzed and discussed. The result showed that there were significant differences among in vitro gas production kinetic parameters. The highest values of A, be, LAG and dry matter degradability （DMD） in vitro occurred in treatments： B 1, B 1, A3 and B 1 respectively, with the lowest values of those kinetic parameters noted for A1, A1, B2 and B3. Correlation analyses indicated that the values of A was positively related to be, both DMD and OMD （organic matter degradability） had a negative correlation with the content of neutral detergent fiber of forges, DMD also had a negative correlation with the content of phosphorus, the coefficients were non-significant between be and LAG, the coefficients were low between fermentation kinetic parameters and nutrition compositions. It is concluded that the reasonable application was 411-821 kg/hm^2 anunonium carbonate after cutting.