施氮水平对甘蔗氮素吸收与利用的影响

以新台糖22号(ROC22)为试材,设15N标记尿素2.5、5.0和7.5g/盆(相当于225、450和675kg/hm2)3个处理,采用网室盆栽试验方式,研究施氮水平对甘蔗氮素吸收与利用的影响。结果表明:甘蔗吸收的氮素17.27%～27.28%来自施用的氮肥,72.72%～82.73%来自土壤和种茎;甘蔗氮肥利用率为34.21%～42.46%。随施氮水平提高,甘蔗干物质积累、氮素积累及来源于肥料氮素的比率显著增加,同时蔗叶对氮素的吸收利用呈上升趋势,但蔗茎对氮素的吸收利用呈下降趋势,氮肥利用率也显著下降。土壤碱解氮和硝态氮在各土层中的含量随施氮水平的提高而增加,且两者在0～20cm土层的积累明显大于20～40cm土层。本试验条件下,甘蔗氮肥施用为尿素5.0g/盆(相当于450kg/hm2)及土层深度为20cm较为适宜。

EFFECTS OF NITROGEN APPLICATION RATES ON NITROGEN UPTAKE AND UTILIZATION BY SUGARCANE

A pot experiment was conducted under greenhouse conditions to evaluate effects of nitrogen application rates(three nitrogen rates treatments of 15N-labeled urea 2.5,5.0 and 7.5 g/pot,equal to 225,450 and 675 kg/hm2,respectively) on nitrogen uptake and utilization of the sugarcane cultivar ROC22.Results showed that the nitrogen accumulation of 17.27%~27.28% in sugarcane was derived from urea,and that of 72.72%~82.73% was from soil and seed-stem.Meanwhile,the nitrogen utilization ratio by sugarcane was 34.21% to 42.46%.In addition,with the enhancement of nitrogen application rates,the accumulation of dry matter and nitrogen significantly as well as the proportion of N from nitrogen fertilizer in sugarcane plant,and the nitrogen utilization by leaves showed an ascending trend,while nitrogen utilization ratio by sugarcane decreased significantly and the nitrogen utilization by stalk displayed a dropping trend.The results also indicated that the alkali hydrolysis nitrogen and nitrate nitrogen content in soil increased when the nitrogen application rates went up,and the accumulation at the soil layer of 0~20cm in both was dramatically larger than that of 20~40cm.In the present study,the suitable amount and location of nitrogen fertilizer applied were urea 5.0g /pot(equal to 450kg/hm2)and 20cm soil depth.