UV-B-Priming Combined with the Soil Application of MWCNT Enhances Rice Growth Performance Under Salt Stress

Soil salinization poses a serious threat to sustainable ecological agricultural development. Most crops are susceptible to salt stress during the growth phase of seed germination and seedling emergence. Seed priming could activate the pre-germination metabolic processes, thereby improving seed germination and seedling growth under abiotic stress conditions. Moreover, multi-walled carbon nanotube (MWCNT), as an important class of carbon nanotubes, has been applied to promote plant growth by enhancing antioxidant defense systems and photosynthetic performance during the seedling stage. In this way, it is worth exploring the combination of pre-germination and post-germination treatments to reduce the damage of salt stress to crops. Therefore, in this study, rice seeds were firstly exposed to UV-B tube in a UV irradiation box for priming treatment (90 min). After emergence, the seedlings were transplanted into pots containing 150 mg L-1 MWCNT and 200 mM NaCl to evaluate the positive effects of nanomaterial on the growth of rice. The results demonstrated that after 28 days of salt stress exposure, the combination of UV-B priming and MWCNT significantly improved the growth performance of rice and minimized the adverse effects of salt stress, as compared with the single UV-B priming or MWCNT treatment, increasing biomass accumulation and the contents of osmoregulation substances, modulating antioxidant enzyme system, improving photosynthetic performance. This study suggested that the integration of seed priming with UV-B and soil application of MWCNT enhanced antioxidant capacity, which might increase photosynthesis and biomass accumulation, thereby improving the salt tolerance of rice.