利用^(15)N示踪技术研究8种禾本科牧草对氮肥的吸收和转化效率

Fertilizer-N Uptake and Conversion Efficiency in 8 Species of Gramineous Pastures by Using ^(15)N-tracing Technique

研究牧草对肥料氮素的吸收及动物转化效率所表现的基因型差异,对指导优良牧草品种的筛选具有重要意义。本研究采用15N同位素示踪方法,通过盆栽试验测定了杂交狼尾草、热研3号俯仰臂形草、热研8号坚尼草、热研11号黑籽雀稗、墨西哥玉米、苏丹草、黑麦草、高羊茅8种禾本科牧草对氮肥的利用效率,并利用15N标记牧草饲喂小白鼠,测定动物对牧草的消化吸收率。结果表明:8种牧草15N肥料利用率为5.197%~29.340%,其中以杂交狼尾草的氮肥利用效率最高;小白鼠对15N标记牧草的消化率为27.67%~68.20%,消化率依次为黑麦草>苏丹草>墨西哥玉米>杂交狼尾草>俯仰臂形草>坚尼草>高羊茅>黑籽雀稗;鼠体对牧草15N的回收率为22.62%~43.90%,表明牧草对氮肥的吸收与转化效率存在明显的基因型差异。综合评价认为,6种夏季牧草品种中,以杂交狼尾草和热研3号俯仰臂形草的15N转化效果较好,冬季牧草品种黑麦草则优于高羊茅。

Forage genotype differences study on absorption efficiency and aiumal transformation rate of N-fertilizer will be of great importance in guiding the excellent forage varieties screening. Effects of 8 species of gramineous forages named as Pennisetum americanum x P. purpureum , Brachiaria decumbens CV. Reyan No. 3, Banicum maximum CV. Reyan No. 8, Paspalum atratum CV. Reyan No. 11, Euchlaena mexicanna Schrad , Sorghum sudanense （PIPER） Stapf , Lolium perenne L and Festuca arundinacea Sehreb on N fertilizer utilization rate were studied by usingIs N-tracing technique in pot experiments, while the digestibility of white mice fed with15 N-labeled forages toward the aboved was investigated. The results showed thatL5 N utilization rates of the 8 pastures were 5. 197% to 29. 340% with the highest rate in Pennisetum americanum x P. purpureum. The digestibility of white mice fed with 8 species15N-labeled forages ranged from 27.67% to 68.20% followed the order of Lolium perenne L. 〉 Sorghum sudanense （PIPER） Stapf 〉 Euchlaena mexicanna Schrad 〉 Pennisetum amerieanum x P. purpureum 〉 Brachiaria decumbens CV. Reyan No. 3 〉 Banicum maximum CV. Reyan No. 8 〉 Festuca arundinacea Schreb 〉 Paspalum atratum CV. Reyan No. 11. 15N recovery rates in mouse body ranged from 22.62% to 43.90% , which indicating a significant difference in genotype in uptake and conversion efficiency of nitrogen fertilizer. The conversion efficiency of Pennisetum americanum × P. purpureum and Brachiaria decumbens CV. Reyan No. 3 were better than the other 4 species of summer forages, while Lolium perenne L. was better than Festuca arundinacea Schreb as winter pasture based on comprehensive evaluation.