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Article|27 Nov 2023|OPEN
Nitrogen–potassium balance improves leaf photosynthetic capacity by regulating leaf nitrogen allocation in apple
Xinxiang Xu1,2,3 , Xu Zhang3 , Wei Ni1,2 , Chunling Liu1,2 , Hanhan Qin1,2 , Yafei Guan1,2 and Jingquan Liu1,2 , Ziquan Feng1,2 , Yue Xing1,2 , Ge Tian1,2 , Zhanling Zhu1,2 , Shunfeng Ge1,2 , , Yuanmao Jiang,1,2 ,
1College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271018, Shandong, China
2Apple Technology Innovation Center of Shandong Province, Tai’an 271018, Shandong, China
3Yantai Academy of Agricultural Sciences, Institute of Pomology, Yan’tai 265500, Shandong, China
*Corresponding author. E-mail:,

Horticulture Research 11,
Article number: uhad253 (2024)
Views: 24

Received: 03 Aug 2023
Accepted: 15 Nov 2023
Published online: 27 Nov 2023


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 (BL), mesophyll limitation (MCL), and stomatal limitation (SL). By setting different N supplies, lowering N levels under low K conditions increased the proportion of water-soluble protein N (Nw) and sodium dodecyl sulfate-soluble proteins (Ns) 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 MCL and BL 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.