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  

EFFECTS OF CO_2 ENRICHMENT, NITROGEN AND SOIL MOISTURE ON PLANT C/N AND C/P IN SPRING WHEAT

作　　者：李伏生[1] 康绍忠[2] 

机构地区：[1]广西大学农学院,南宁530005 [2]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

出　　处：《植物生态学报》2002年第3期295-302,共8页Chinese Journal of Plant Ecology

基　　金：国家重大基础研究计划项目 (G19990 1170 8);国家杰出青年科学基金项目 ( 4 972 5 10 2 )

摘　　要：试验设两种CO2 浓度水平 (35 0 μmol·mol-1和 70 0 μmol·mol-1) ,两种土壤水分处理 (湿润、干旱 )和 5种N肥施用水平 (0、5 0、10 0、15 0、2 0 0mg·kg-1土 )。结果表明 ,CO2 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CO2 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CO2 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。CO2 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CO2 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 %～ 1.2 7%。CO2 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。CO2 浓度增加 ,地上部和根系C/N比率增加 ,这是高CO2 浓度引起地上部和根系N浓度下降的结果。Spring wheat (Triticum aestivum L.) was treated with two atmospheric CO 2 concentrations (350 μmol·mol -1 and 700 μmol·mol -1 ), two levels of soil moisture (wet and drought) and five rates of nitrogen fertilizer (0,50,100,150,200 mg·kg -1 soil ). Results showed elevated CO 2 decreased 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 compared to the drought treatments, and increased dramatically with increasing N application irrespective of the CO 2 concentration. The reduction in the movement of nutrients to the plant roots through mass flow due to the increase in water use efficiency (WUE) and the increase in N use efficiency at elevated CO 2 can 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. CO 2 enrichment generally reduced shoot C content, but did not affect root C content. The effect of elevated CO 2 on root C content varied with soil nitrogen status. In low N treatment, root C content increased, with the absolute C content increment of 0.95%-1.18%. In high N treatment, root C decreased, with the absolute C content reduction of 0.70%-1.27%. Enriched CO 2 concentration increased shoot and root C/N and shoot C/P ratio, which may reduce the decomposition 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 CO 2 concentration.

关 键 词：水分条件 CO2浓度升高 小麦 碳氮比 碳磷比 土壤水分 C/N C/P 施氮水平 氮肥 

分 类 号：Q945[生物学—植物学]