Nano-Priming with La 2 O 3 Improves Early Growth and Regulates Physio-Biochemical Mechanisms in Fragrant Rice Against Cadmium Toxicity

Purpose Cadmium (Cd) is amongst the most toxic heavy metals which severely affects the plant growth. Application of nanoparticles (NPs) could be helpful to negate the deleterious impacts of Cd stress in crop plants. Methods In this study, seed priming of two fragrant rice cultivars, i.e., Xiangyaxiangzhan and Yuxiangyouzhan, applied with four levels of Lanthanum oxide nanoparticles (La 2 O 3 NPs) i.e., 0, 50, 100, and 300 mg L –1 , grown under three Cd levels i.e., 0, 50, and 100 mg L −1 . Result Results revealed that the nano-priming with La 2 O 3 significantly improved the seed germination rate under the Cd stress. Nano-priming exhibited substantial improvements in the total fresh weight, shoot length, root length, leaf sheath length and prophyll leaf length under the Cd stress. Moreover, nano-priming with La 2 O 3 NPs substantially modulate the antioxidant activities i.e., superoxide dismutase, peroxidase, and catalase, and enhanced the α-amylase activity. Nano-priming further reduced the malondialdehyde, metallothionein, glutathione, proline, and soluble protein contents whilst enhanced the chlorophyll and carotenoids contents. Conclusions Seed priming with La 2 O 3 NPs substantially enhanced the early growth of rice seedlings by improving morphological attributes and modulating the physiological and biochemical responses under Cd toxicity. The insights gained from this study may be of assistance to understand the effects of La 2 O 3 NPs on early growth of rice, and its potential applications in enhancing the Cd tolerance of crops.