不同氮和水分条件下CO_2浓度升高对小麦碳氮比和碳磷比的影响

植物生态学报　2002,26(3)295～302 ΞActa Phytoecologica Sinica

不同氮和水分条件下CO2浓度升高对小麦

碳氮比和碳磷比的影响

李伏生

(广西大学农学院,南宁　530005)

康绍忠

(西北农林科技大学教育部旱区农业水土工程重点实验室,陕西杨凌　712100)

摘　要　试验设两种C O2浓度水平(350μm ol・m ol-1和700μm ol・m ol-1),两种土壤水分处理(湿润、干旱)和5种N肥

施用水平(0、50、100、150、200mg・kg-1土)。结果表明,C O2浓度增加,地上部氮(N)磷(P)浓度下降,根系N浓度略

有下降。无论C O2浓度是升高或是当前水平,与干旱处理相比,湿润处理的地上部和根系N浓度明显降低;地上部

和根系N浓度随氮肥用量增加而增加。小麦体内N浓度下降,是因为C O2浓度升高,水分利用效率增加,这将减少

质流运送养分到根系为作物利用以及氮利用效率提高之故。地上部P浓度降低是稀释效应的结果。C O2浓度增

加,地上部含碳(C)量趋于降低,但不影响根系C含量,高C O2浓度对根系C含量因土壤氮状况不同而异,低氮时根

系含C量增加,含C量绝对值增加0.95%～1.18%,而高氮时表现降低,平均降低0.70%～1.27%。C O2浓度升高,

地上部和根系C/N比率和地上部C/P比率增加,这将会降低植物残体的腐解速率。C O2浓度增加,地上部和根系

C/N比率增加,这是高C O2浓度引起地上部和根系N浓度下降的结果。

关键词　C O2浓度升高　土壤水分　氮　C/N　C/P

EFFECTS OF CO2ENRICH MENT,NITR OGEN AN D SOI L MOISTURE

ON P LANT C/N AN D C/P IN SPRING WHEAT

LI Fu-Sheng

(Agricultural College,Guangxi Univer sity,Nanning,530005,China)

K ANG Shao-Zhong

(K ey Laboratory o f Agricultural Soil&Water Engineering in the Arid and Semiarid Areas,Ministry o f

Education,Northwest Sci-Tec Univer sity o f Agriculture and Forestry,Yangling,Shaanxi712100,China)

Abstract　S pring wheat(Triticum aestivum L.)was treated with tw o atm ospheric C O2concentrations(350

μm ol・m ol-1and700μm ol・m ol-1),tw o levels of s oil m oisture(wet and drought)and five rates of nitrogen

fertilizer(0,50,100,150,200mg・kg-1s oil).Results showed elevated C O2decreased shoot N and P content

significantly and reduced root N content slightly.Shoot and root N concentration was significantly lower in the

well-watered treatments com pared to the drought treatments,and increased dramatically with increasing N ap2

plication irrespective of the C O2concentration.The reduction in the m ovement of nutrients to the plant roots

through mass flow due to the increase in water use efficiency(W UE)and the increase in N use efficiency at el2

evated C O2can explain the reduction of shoot and root N concentration.The decrease in shoot P content was

the result of dilution of P due to the increase in shoot dry mass.C O2enrichment generally reduced shoot C

content,but did not affect root C content.The effect of elevated C O2on root C content varied with s oil nitrogen

status.In low N treatment,root C content increased,with the abs olute C content increment of0.95%-1.

18%.In high N treatment,root C decreased,with the abs olute C content reduction of0.70%-1.27%.En2

riched C O2concentration increased shoot and root C/N and shoot C/P ratio,which may reduce the decom posi2

tion rate of plant litter.The increase in shoot and root C/N ratio was the result of the decrease in N content

under the elevated C O2concentration.

K ey w ords　C O2concentration enrichment,S oil m oisture,Nitrogen,C/N,C/P

预计到21世纪末期大气C O2浓度将会在目前水平上增加1倍,约700μm ol・m ol-1左右(Wats on et

Ξ 收稿日期:2001206211　接受日期:2001210209

基金项目:国家重大基础研究计划项目(G1999011708)和国家杰出青年科学基金项目(49725102)

E-mail:fushengl@,lifusheng@