水稻光合碳在植株-土壤系统中分配与稳定对施磷的响应

为探究稻田土壤光合碳的输入及分配对施磷的响应特征，本研究选用籼性常规水稻品种（中早39），在两个施磷（0 mg·kg^-1和80 mg·kg^-1；分别记为P₀和P₈₀）条件下进行盆栽试验，同时采用¹³CO₂连续标记技术量化光合碳在水稻-土壤系统中的分配.结果表明，施磷显著增加光合碳在水稻地上部的分配，降低其在根际土的分配（P<0.05）；施磷使拔节期水稻的光合碳含量增加了70%，根系干重降低了31%.与不施磷相比，施磷显著提高了水稻地上部全碳含量0.31 g·pot^-1（P<0.05），显著降低了水稻根冠比；施磷使进入非根际土壤微生物量的光合碳（¹³C-MBC）显著增加了0.03 mg·kg^-1，但降低其在根际土壤的分配；光合碳在非根际土壤颗粒态有机碳（POC）和矿物结合态有机碳（MOC）的分配对施磷的响应不显著，但在根际土壤施磷处理显著降低了其在POC中的含量.因此，施磷增加了光合碳在水稻-土壤系统的分配，但降低了光合碳在土壤中的积累.本研究探讨施磷对水稻光合碳在水稻-土壤系统的分配及其稳定的影响，为缺磷土壤的合理施用磷肥及其对土壤有机碳积累的影响提供理论基础和数据支撑；对理解稻田土壤光合碳的传输与分配特征及其固碳潜力具有重要意义.

Allocation and Stabilization Responses of Rice Photosynthetic Carbon in the Plant-Soil System to Phosphorus Application

This research studied the response of the input and allocation of photosynthetic carbon (C) to phosphorus (P) in paddy soils. Two treatments were conducted in this experiment:no P application (P₀) and the application of 80 mg·kg^-1 of P (P₈₀). The rice cultivar was the indica Zhongzao 39. The ¹³C-CO₂ continuous labeling technique was used to identify the photosynthetic C distribution of the rice. The results showed that the application of P₈₀ significantly increased the photosynthates allocation in the rice aboveground, but reduced their allocation in the rhizosphere soil (P<0.05). At the jointing stage, P₈₀ application increased the photosynthetic C content of the rice by 70%, but the root dry weight decreased 31%. Compared with P₀, the total C content of the aboveground rice was increased 0.31 g·pot^-1 by P₈₀. The ratio of rice roots to shoots decreased with the P₈₀ treatment. Moreover, P₈₀ application led to an increase in the photosynthetic microbial biomass in the non-rhizosphere soil C (¹³C-MBC) of 0.03 mg·kg^-1, but still decreased its allocation in the rhizosphere soil. The allocation of photosynthetic C to the particulate organic matter fraction (POC) and mineral fraction (MOC) in the non-rhizosphere soil showed no significant differences between P₀ and P₈₀. Additionally, the P₈₀ fertilization treatment significantly lowered the content of POC in the rhizosphere soil. In summary, P application increased the allocation of photosynthetic C in the soil-rice system, but reduced the accumulation of photosynthetic C in the soil. This research provided a theoretical basis and data supporting the rational application of P fertilizer, and was also of great significance as a study of the transportation and allocation of photosynthetic C and its sequestration potential response to the application of P to the rice soil.