科研之友
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摘要
Although water conservation in rice production has become increasingly important, the effects of water management on the allocation and dynamics of carbon (C) within the rice-soil system remain unknown. We compared the allocation and dynamics of C assimilated by rice under continuously flooded, non-flooded and alternate water regimes. Rice (Oryza sative L. cv. Luliangyou 996) was labeled with (CO2)-C-14 and harvested 7 times within 45 days. More C-14 was released from roots into the soil in non-flooded and alternate water regimes treatments. Microbial C-14 decreased with time after the labeling and was lowest under flooded condition. Roots and rhizomicrobial respiration followed the order of non-flooded > alternate water regimes > flooded treatment. Water management affected C-14 distribution in aggregates with more C-14 in macroaggregates in the non-flooded treatment. Estimated amounts of C transferred remaining belowground by rice 45 days after labeling were 1,986, 2,827 and 2,472 kg C ha(-1), of which rhizodeposition accounted for about 41 %, 16 % and 30 % of C transferred belowground under non-flooded, flooded and alternate water regimes, respectively. Water management affected the allocation and dynamics of recently assimilated C within the rice-soil system and also changed the relative contribution of rhizodeposition to C transferred belowground. This study suggests the differences in the driving mechanisms of C sequestration under flooded vs. non-flooded and alternate water regimes.
