Nitrogen is an essential macronutrient required for plant growth. In this study, the relationships between plant growth, photosynthetic capability, chlorophyll fluorescence characteristics and nitrogen forms in response to low-nitrogen stress were studied in tomato grafted with different nitrogen-use-efficiency tomato seedlings. Using tomato plants grafted with different rootstocks, we found that, under low-nitrogen stress, plant growth, chlorophyll contents, net photosynthetic rate (Pn), maximal photochemical efficiency (F_v/F_m), the total nitrogen (TN) concentration, and nitrate reductase (NR) activity were significantly inhibited but that the ammonium-nitrogen (NH₄⁺-N) content in the roots significantly increased. High-nitrogen-use-efficiency tomato grafted plants exhibited significantly enhanced plant growth but reduced Pn, F_v/F_m, TN content and NR activity under low-nitrogen conditions compared to the grafted seedlings of the low-nitrogen-use-efficiency genotype. In addition, tomato plants grafted onto high-nitrogen efficient rootstock presented reduced damage caused by excessive accumulation of NH₄⁺-N in the roots under low-nitrogen stress. Our results indicate that tomato plants grafted onto high-nitrogen efficient rootstock presented enhanced absorption and utilization of nitrogen and maintained growth by promoting the use efficiency of light energy under low-nitrogen stress.

氮是植物生长所需的必需常量营养素。本研究在嫁接不同氮利用效率番茄幼苗的番茄中研究了植物生长、光合能力、叶绿素荧光特性和响应低氮胁迫的氮形态之间的关系。利用嫁接不同砧木的番茄植株，我们发现在低氮胁迫下，植株生长、叶绿素含量、净光合速率（Pn）、最大光化学效率（F _v / F _m）、总氮（TN）浓度、和硝酸还原酶 (NR) 活性受到显着抑制，但氨氮 (NH ₄ ⁺-N) 根中的含量显着增加。与低氮利用效率基因型的嫁接苗相比，高氮利用效率番茄嫁接植株在低氮条件下表现出显着增强的植株生长，但降低了Pn、F _v / F _m、TN含量和NR活性. 此外，嫁接在高氮高效砧木上的番茄植株在低氮胁迫下减少了根部NH ₄ ⁺ -N过度积累造成的损害。我们的研究结果表明，嫁接在高氮高效砧木上的番茄植株在低氮胁迫下通过提高光能的利用效率来增强氮的吸收和利用并保持生长。