Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture/Microelement Research Center/College of Resources and Environment, Huazhong Agricultural University, Shizishan Street 1, Wuhan, 430070, China.
Department of Crop Sciences, Institute of Applied Plant Nutrition (IAPN), Georg-August-University Göttingen, Carl-Sprengel-Weg 1, 37075, Göttingen, Germany.
BMC Plant Biol. 2019 Jul 10;19(1):302. doi: 10.1186/s12870-019-1894-8.
Nitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. Studying the interactive effects of N and K on regulating N allocation and photosynthesis (P) of rice leaves will be of great significance for further increasing leaf P, photosynthetic N use efficiency (PNUE) and grain yield. We measured the gas exchange of rice leaves in a field experiment and tested different kinds of leaf N based on N morphology and function, and calculated the interactive effects of N and K on N allocation and the PNUE.
Compared with N0 (0 kg N ha) and K0 (0 kg KO ha) treatments, the P was increased by 17.1 and 12.2% with the supply of N and K. Compared with N0K0 (0 kg N and 0 kg KO ha), N0K120 (0 kg N and 120 kg KO ha) and N0K180 (0 kg N and 180 kg KO ha), N supply increased the absolute content of photosynthetic N (N) by 15.1, 15.5 and 10.5% on average, and the storage N (N) was increased by 32.7, 64.9 and 72.7% on average. The relative content of N was decreased by 5.6, 12.1 and 14.5%, while that of N was increased by 8.7, 27.8 and 33.8%. Supply of K promoted the transformation of N to N despite the leaf N content (N) was indeed decreased. Compared with N0K0, N180K0 (180 kg N and 0 kg KO ha) and N270K0 (270 kg N and 0 kg KO ha), K supply increased the relative content of N by 17.7, 8.8 and 7.3%, and decreased the relative content of N by 24.2, 11.4 and 8.7% respectively.
This study indicated the mechanism that K supply decreased the N but increased the N content and then increased leaf P and PNUE from a new viewpoint of leaf N allocation. The supply of K promoted the transformation of N to N and increased the PNUE. The decreased N mainly resulted from the decrease of non-protein N. Combined use of N and K could optimize leaf N allocation and maintain a high leaf N content and PNUE.
氮（N）和钾（K）是调节叶片光合作用的两种重要矿质营养元素。研究 N 和 K 对调节水稻叶片氮分配和光合作用（P）的相互作用，对于进一步提高叶片 P、光合 N 利用效率（PNUE）和籽粒产量具有重要意义。本研究通过田间试验测定了水稻叶片的气体交换，并基于 N 形态和功能对不同种类的叶片 N 进行了测试，计算了 N 和 K 对氮分配和 PNUE 的相互作用。
与 N0（0kgNha）和 K0（0kgKOha）处理相比，N 和 K 的供应分别使 P 增加了 17.1%和 12.2%。与 N0K0（0kgN 和 0kgKOha）相比，N0K120（0kgN 和 120kgKOha）和 N0K180（0kgN 和 180kgKOha），N 供应平均使光合 N（N）的绝对含量增加了 15.1%、15.5%和 10.5%，而储存 N（N）则平均增加了 32.7%、64.9%和 72.7%。N 的相对含量降低了 5.6%、12.1%和 14.5%，而 N 的相对含量增加了 8.7%、27.8%和 33.8%。尽管叶片 N 含量（N）确实减少，但 K 的供应促进了 N 向 N 的转化。与 N0K0 相比，K 供应使 N180K0（180kgN 和 0kgKOha）和 N270K0（270kgN 和 0kgKOha）的 N 相对含量分别增加了 17.7%、8.8%和 7.3%，N 相对含量分别降低了 24.2%、11.4%和 8.7%。
本研究从叶片氮分配的新视角表明，K 供应降低 N 但增加 N 含量，从而提高叶片 P 和 PNUE 的机制。K 的供应促进了 N 向 N 的转化，提高了 PNUE。减少的 N 主要是由于非蛋白 N 的减少。N 和 K 的联合使用可以优化叶片氮分配，维持高叶片氮含量和 PNUE。
