摘要
采用盆栽试验,研究4种氮肥水平下杂交狼尾草和墨西哥玉米在不同生长期叶和根的硝酸盐含量,茎叶粗蛋白含量以及不同氮肥水平的氮素利用率。结果表明,杂交狼尾草叶和墨西哥玉米根的硝酸盐含量受施氮量影响较大,二者之间都呈正相关。从生长过程来看,随着牧草的生长,叶的硝酸盐含量有少量升高,根的硝酸盐含量先升高后降低,但在氮肥水平下,2种牧草各个时期的硝酸盐含量均低于硝酸盐有毒限量指标0.25%。另一方面,随着施氮水平的提高,2种牧草的粗蛋白含量逐渐升高,杂交狼尾草粗蛋白含量最高达23.23%,墨西哥玉米粗蛋白含量最高达25.80%,但2种牧草的干物质生产效率、粗蛋白质生产效率和氮素表观回收率均降低,说明施氮量越大,氮素利用效率越低,损失率也越大。从生长过程来看,随着2种牧草的生长其粗蛋白含量均逐渐降低。综合考虑,笔者认为在山地红壤中种植杂交狼尾草和墨西哥玉米以施纯氮200 kg/hm2就能满足牧草高产优质的生产需求。
A pot experiment was conducted to investigate the effects of different N applied rates （100,200, 300, and 400 kg/hm^2） on nitrate accumulation in leaves and roots, protein content in stems and leaves, and the N utilization rates by pennisetum americanum × P. purpureum and Euchlaena mexicana during different growing stages. There was a positive correlation between the leaf nitrate content of the two forages and N application rate, but N rates had no significant influence on root nitrate content. With growth of the forages, leaf nitrate content increased slightly, and root nitrate content rose at first then declined, but the nitrate contents of the forages during all stages of this experiment were below the poisonous limit of 0.25%. The DMPE, CPPE and NARR contents of the two forages diminished with increased N application but protein content showed an upward tendency with the highest protein contents of P. americanum× P. purpureum and of E. mexicanna reaching 23.23% and 25.80% respectively. This means that N utilization rates decreased with increased N application rates, resulting in a gradual decrease of the protein content with growth of the forages. In a comprehensive assessment, the recommended dose of fertilizer N for P. americanum×P, purpureum and E. mexicanna was 200 kg/hm^2 in hilly areas of red soil.
出处
《草业学报》
CSCD
2008年第3期47-52,共6页
Acta Prataculturae Sinica
基金
国家重大基础研究前期研究项目(2005CCA01300)
福建省科技重大专项前期研究项目(2005NZ1022、2005YZ1004)
福建省发改委“五新”项目
福建省财政专项--福建省农业科学院科技创新团队建设基金(STIF-Y01)资助
关键词
禾本科牧草
施氮量
硝酸盐
粗蛋白质
grass forage
N fertilizer rates
nitrates crude protein
