Nitrogen-potassium balance improves leaf photosynthetic capacity by regulating leaf nitrogen allocation in apple

Xinxiang Xu; Xu Zhang; Wei Ni; Chunling Liu; Hanhan Qin; Yafei Guan; Jingquan Liu; Ziquan Feng; Yue Xing; Ge Tian; Zhanling Zhu; Shunfeng Ge; Yuanmao Jiang

doi:10.1093/hr/uhad253

Nitrogen-potassium balance improves leaf photosynthetic capacity by regulating leaf nitrogen allocation in apple

Hortic Res. 2023 Nov 27;11(1):uhad253. doi: 10.1093/hr/uhad253. eCollection 2024 Jan.

Authors

Xinxiang Xu^{1

2

3}, Xu Zhang³, Wei Ni^{1

2}, Chunling Liu^{1

2}, Hanhan Qin^{1

2}, Yafei Guan^{1

2}, Jingquan Liu^{1

2}, Ziquan Feng^{1

2}, Yue Xing^{1

2}, Ge Tian^{1

2}, Zhanling Zhu^{1

2}, Shunfeng Ge^{1

2}, Yuanmao Jiang^{1

2}

Affiliations

¹ College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China.
² Apple Technology Innovation Center of Shandong Province, Tai'an 271018, Shandong, China.
³ Yantai Academy of Agricultural Sciences, Institute of Pomology, Yan'tai 265500, Shandong, China.

Abstract

Nitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. However, the influence of N and K interaction on photosynthesis is still not fully understood. Using a hydroponics approach, we studied the effects of different N and K conditions on the physiological characteristics, N allocation and photosynthetic capacity of apple rootstock M9T337. The results showed that high N and low K conditions significantly reduced K content in roots and leaves, resulting in N/K imbalance, and allocated more N in leaves to non-photosynthetic N. Low K conditions increased biochemical limitation (B_L), mesophyll limitation (M_CL), and stomatal limitation (S_L). By setting different N supplies, lowering N levels under low K conditions increased the proportion of water-soluble protein N (N_w) and sodium dodecyl sulfate-soluble proteins (N_s) by balancing N/K and increased the proportion of carboxylation N and electron transfer N. This increased the maximum carboxylation rate and mesophyll conductance, which reduced M_CL and B_L and alleviated the low K limitation of photosynthesis in apple rootstocks. In general, our results provide new insights into the regulation of photosynthetic capacity by N/K balance, which is conducive to the coordinated supply of N and K nutrients.