Effects of harvesting stage on botany characters ,biomass and content of N ,P and K of hybrid varie-ties in Miscanthus were studied with three hybrid varieties as materials .The results showed that:with the delay of harvesting stage,biomass of three varieties was decreased ,significant decrease of biomass of Xiangzamang No .2 and Xiangzamang No.3 began on 20th Oct,while that of Xiangzamang No.1 began on 20th Nev.Biomass of three varie-ties was over 40 t/ha on 20th Dec,and it was 40.6,38.8,31.6 t /ha on 20th Jan,respectively.SPAD value of leav-es and water content of three varieties showed decrease trend from 20th Oct,while the varietal difference in signifi-cant decrease stage was observed .Content of N,P and K of three varieties showed decrease trend from 20th Oct, while the varietal difference in significant decrease stage of N and K was observed .Looked from the average of three varieties,content of N,P and K was 1.1%,0.15% and 0.76% respectively on 20th Oct,while it decreased to 0.32%,0.07% and 0.20% respectively on 20th Jan.Comprehensively considered SPAD value of leaves ,biomass, content and accumulation of N,P and K,the optimal harvesting stage of Xiangzamang No .2 should be after 20th Dec,and that of Xiangzamang No.3 and Xiangzamang No.1 should be after 20th Dec.% 以3个芒属植物杂交种为材料，研究了收获期对芒属植物杂交种植物学性状、生物产量与氮磷钾含量的影响。结果表明，随着收获期的推迟，3个品种生物产量均呈下降趋势，湘杂芒2号和湘杂芒3号自10月20日开始显著下降，而湘杂芒1号自11月20日才开始显著下降，至12月20日，3个品种生物产量仍在40 t/hm 2以上，至次年1月20日，3个品种生物产量分别为40．6，38．8，31．6 t/hm 2；3个品种叶片 SPAD 值与植株含水量均从10月20日开始表现下降趋势，但二者的显著下降时期均存在品种间差异；3个杂交种的氮、磷、钾含量自10月20日开始下降，但氮、钾含量的大幅度下降时期具有品种间差异。3个杂交种平均来看，氮磷钾含量分别从10月20日的1．1％，0．15％，0.76％下降到1月20日的0．32％，0．07％，0．20％。综合叶片 SPAD 值、植株含水量、生物产量、植株氮磷钾含量与累积量等因素，湘杂芒2号适宜收获期应在11月20日以后，而湘杂芒3号与湘杂芒1号应在12月20日以后。
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