Effects of low-temperature stress during rice heading stage on carbon and nitrogen allocation in paddy eco-system of northeastern China

Tao Sun ¹ Junmei Ruan ² Tiehua Cao ³ Li Yao ¹ Zichao Zhao ¹ Jun Zhang ⁴ Jiarui Li ⁴ Aixing Deng ⁴ Haotian Chen ⁴ Xinhao Gao ¹ Zhenwei Song ^4*

• ¹ Institute of Agricultural Resources and Environment, Shandong Academy of Agricultural Sciences, Ji’nan, China
• ² Meizhou Academy of Agriculture and Forestry Sciences, Meizhou, China
• ³ Jilin Academy of Agricultural Sciences (CAAS), Changchun, Jilin Province, China
• ⁴ Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China

In high-latitude area, climate change has brought about recurrent chilling stress that adversely impacts the sustainable production of rice and alters the distribution of carbon (C)and nitrogen (N) in paddy ecosystems.Yet, a comprehensive understanding of how the paddy ecosystem's C and N allocation responds to lowtemperature stress during critical growth stages remains elusive. Hereby, a rice pot experiment of two varieties combined with 13 C and 15 N isotope labelling method was conducted to evaluate how lowtemperature stress at heading stage affects rice yield, and above-and below-ground C and N partitioning.The results revealed that low-temperature stress significantly reduced rice grain yield of JN809 (sensitive to low-temperature stress) and J88 (tolerant to low-temperature stress) varieties by 27.6% and 21.4%, respectively, This stress tendency increased C and N accumulation in rice stems and leaves, while concurrently decreasing C and N accumulation in panicles. Specifically, under low-temperature stress, the 13 C isotope content in stems and leaves was found to be 14.0% and 19.0% higher than in the control treatment, while the 13 C and 15 N isotope contents in their panicles were 29.3% and 22.5% lower, respectively. The lowtemperature tolerant variety (J88) demonstrated a reduced effect of low-temperature stress on rice yield and C, N allocation due to efficient resource reallocation and stress tolerance mechanisms. The findings of this study provide a foundation for developing rice breeding and cultivation techniques that can enhance rice resilience and adaptability to climate change. Additionally, it informs strategies to optimize C and N sequestration practices in rice fields, ensuring high yields and efficient resource utilization.