用^(13)C脉冲标记方法研究施肥与地膜覆盖对玉米光合碳分配的影响

EFFECT OF FERTILIZATION AND PLASTIC FILM MULCHING ON DISTRIBUTION OF PHOTOSYNTHETICALLY FIXED CARBON IN MAIZE:EXPLORED WITH^(13)C PULSE LABELING TECHNIQUE

基于沈阳农业大学棕壤长期定位试验站不同施肥与地膜覆盖处理,采用原位13CO2脉冲标记的方法示踪了13C在玉米-土壤系统中的转移与分配,探讨了施肥与地膜覆盖对玉米光合碳动态变化的影响。结果表明:玉米-土壤系统光合固定碳转移较快,且分配差异较大,其δ13C值在标记1 d表现为茎叶>根>根际土壤>土体,且同一施肥处理下传统栽培高于覆膜栽培。标记15 d玉米植株和根际土壤δ13C值降低,而土体δ13C值却略有升高。传统栽培不施肥处理对13C富集程度最大,其中茎叶和根δ13C值在标记1 d分别为1 568‰和598‰;标记15 d为178‰和147‰。玉米-土壤系统13C固定比例在标记1 d和15 d分别为64.01%和38.65%,且13C分配按茎叶、根、根际土壤、土体顺序依次降低。覆膜施有机肥处理显著提高了光合固定13C数量及13C在玉米和土壤中的分配比例,是促进13C同化与分配的主要方式。

The in-situ 13CO2 pulse labeling technique was used to trace the fate of 13C in maize-soil system and asses the effect of fertilization and plastic film mulching on the dynamics of photosynthetically fixed carbon by maize planted in the long-term Brown Earth Experiment Station in Shenyang Agricultural University. Results show that the carbons were quickly translocated and distributed unevenly in the maize-soil system on D 1 （the first day after labeling）, showing an order of shoots 〉 roots 〉 rhizosphere soil 〉 bulk soil, and unmulched 〉 mulched in δ13C value. The δ13C values declined in maize plants and rhizosphere soil, but slightly increased in bulk soil with the time passing by from D 1 to D 15. Treatment CK was the highest in 13C enrichment with average δ13C value in shoots and roots reaching 1 568‰ and 598‰, respectively, on D 1 and 178‰ and 147‰, respectively, on D 15. The 13C fixed in the maize plants accounted for 64.01% of the total in the system on D 1 and for 38.65% on D 15. The distribution of 13C showed a declining trend in the order of shoots 〉 roots 〉 rhizosphere soil 〉 bulk soil in the plant-soil system. The experiment clearly demonstrated that the treatment of mulching plus organic manure significantly increased photosynthetical fixation of 13C and the allocation of 13C in maize plant and soil, which means that it is an important practice to improve carbon assimilation and distribution in the maize-soil system.