Abstract: The effects of nitrogen application quantity(middle level at 300 kg/hm²;high level at 600 kg/hm²) and mode(base application at one time and separate application at three times) on the nitrate nitrogen content in stem and leaf and forage yield of Sorghum bicolor×S.sudanense cv.Wancao No.2 were studied in this paper in order to provide the scientific instruction on nitrogen fertilizer application and utilization.The results show that: the content of NO₃-N in leaf was obviously lower than that of stem(P<0.05),the NO₃-N content in stem and leaf harvested in the third time was highest,the NO₃-N contents in both the stem and leaf after nitrogen application were higher than those in CK.Under the same nitrogen application mode,the content of NO₃-N of each harvest(H1,H2,and H3) increased along with the increasing of nitrogen application quantity.The activity of nitrate reductase(NR) from all nitrogen treatments was higher than that in CK and increased with the proceeding of harvests.For the base N application at one time,the yields of fresh and dry matter declined with the increasing of N application quantity.For the separate N application,the yields of fresh and dry matter increased with the increasing of N application quantity.The yields from the separate application treatment with equal N quantity(N3 and N4) were obviously higher than those under the one time application treatments(N1 and N2)(P<0.05).The crude protein production under N application treatments was higher than those in CK(P<0.05);among which the yield under N4 treatment was highest and reached to 5218 kg/hm².The production efficiencies of dry matter,crude protein,and nitrogen recovery,etc.declined with the increasing of nitrogen application quantity.The dry matter production efficiency and nitrogen recovery efficiency under the separate application treatment with equal N quantity were higher than those by base N application at one time,i.e.N3>N1 and N4>N2.The crude protein production efficiency from high N application quantity with separate applications was higher than that in base N application at one time.

Key words: Sorghum bicolor×S.sudanense cv.Wancao No.2, Nitrogen, Accumulation of nitrate nitrogen, Yield

摘要： 研究2个施氮水平(中氮300 kg/hm²和高氮600 kg/hm²)和2种施肥方式(一次基施和平均3次分施)对皖草2号植株茎杆、叶片硝态氮(NO₃-N)累积及产量的影响。结果表明:皖草2号叶片NO₃-N含量显著低于茎秆(P<0.05),其第3次收获草(H3)茎杆和叶片中NO₃-N含量最高;施氮处理植株茎秆、叶片NO₃-N含量均高于对照(N0)。同种施肥方式下,各茬收获草(H1、H2、H3)的NO₃-N含量随施氮量增加而升高。所有氮素处理硝酸还原酶(NR)活性均高于对照,且随收获次数的增加NR活性升高。一次性基施处理,鲜干物质产量随施氮量增加而降低;分次施肥处理,鲜干物质产量随施氮量的增加而升高;相同施氮量分次施用(N3和N4)产草量显著高于一次性施用(N1和N2)(P<0.05)。施氮处理粗蛋白产量均显著高于对照(P<0.05),其中N4处理产量最高,达到5218 kg/hm²。随施氮量的增加干物质生产效率、粗蛋白生产效率和氮肥吸收利用率等降低。干物质生产效率和氮肥吸收利用率变化情况是相同施氮量分次施肥处理高于一次性基施处理,即:N3>N1,N4>N2,粗蛋白生产效率是高施氮量分次处理高于一次基施处理。

关键词: 皖草2号, 氮素, 硝态氮累积, 产量