College of Resources, Hunan Agricultural University, Changsha, 410128, People's Republic of China.
Yiyang City Academy of Agricultural Sciences, Yiyang, 413046, People's Republic of China.
Planta. 2024 Jan 29;259(2):46. doi: 10.1007/s00425-023-04327-5.
Foliar NAA increases photosynthate supplied by enhancing photosynthesis, to strengthen root activity and provide a large sink for root carbohydrate accumulation, which is beneficial to acquire more nitrogen. The improvement of grain yield is an effective component in the food security. Auxin acts as a well-known plant hormone, plays an important role in maize growth and nutrient uptake. In this study, with maize variety Zhengdan 958 (ZD958) as material, the effects of auxin on nitrogen (N) uptake and assimilation of seedling maize were studied by hydroponic experiments. With water as the control, naphthalene acetic acid (NAA, 0.1 mmol/L) and aminoethoxyvinylglycine (AVG, 0.1 mmol/L, an auxin synthesis inhibitor) were used for foliar spraying. The results showed that NAA significantly improved photosynthetic rate and plant biomass by 58.6% and 91.7%, respectively, while the effect of AVG was opposite to that of NAA. At the same time, key enzymes activities related N assimilation in NAA leaves were significantly increased, and the activities of nitrate reductase (NR), glutamine synthetase (GS) and glutamate synthase (GOGAT) were increased by 32.3%, 22.9%, and 16.2% in new leaves. Furthermore, NAA treatment promoted underground growth. When compared with control, total root length, root surface area, root tip number, branch number and root activity were significantly increased by 37.8%, 22.2%, 35.1%, 28.8% and 21.2%. Root growth is beneficial to N capture in maize. Ultimately, the total N accumulation of NAA treatment was significantly increased by 74.5%, as compared to the control. In conclusion, NAA foliar spraying increased endogenous IAA content, and enhanced the activity of N assimilation-related enzymes and photosynthesis rate, in order to build a large sink for carbohydrate accumulation. In addition, NAA strengthened root activity and regulated root morphology and architecture, which facilitated further N uptake and plant growth.
叶片喷施 NAA 可通过增强光合作用来增加光合产物供应，从而增强根系活力并为根碳水化合物积累提供一个大的库，这有利于获得更多的氮。提高谷物产量是粮食安全的有效组成部分。生长素作为一种众所周知的植物激素，在玉米生长和养分吸收中发挥着重要作用。在这项研究中，以玉米品种郑单 958（ZD958）为材料，通过水培实验研究了生长素对幼苗玉米氮吸收和同化的影响。以水为对照，用萘乙酸（NAA，0.1mmol/L）和氨基乙氧基乙烯基甘氨酸（AVG，0.1mmol/L，生长素合成抑制剂）进行叶片喷施。结果表明，NAA 分别显著提高了光合速率和植物生物量 58.6%和 91.7%，而 AVG 的作用则与 NAA 相反。同时，叶片中与氮同化相关的关键酶活性显著增加，新叶中硝酸还原酶（NR）、谷氨酰胺合成酶（GS）和谷氨酸合酶（GOGAT）的活性分别提高了 32.3%、22.9%和 16.2%。此外，NAA 处理促进了地下生长。与对照相比，总根长、根表面积、根尖数、分枝数和根活力分别显著增加了 37.8%、22.2%、35.1%、28.8%和 21.2%。根的生长有利于玉米对氮的吸收。最终，与对照相比，NAA 处理的总氮积累量显著增加了 74.5%。综上所述，叶片喷施 NAA 可增加内源性 IAA 含量，增强与氮同化相关的酶活性和光合作用速率，从而为碳水化合物积累建立一个大的库。此外，NAA 增强了根系活力，调节了根系形态和结构，从而促进了进一步的氮吸收和植物生长。
