Abstract
BackgroundCadmium (Cd) is amongst the most toxic heavy metals that severely affects crop growth, whereas application of nanoparticles (NPs) to negate the toxic effects of heavy metals could be an effective management approach. In the present study, the seeds of two fragrant rice varieties i.e., Yuxiangyouzhan and Xiangyaxiangzhan under normal and Cd stress conditions i.e., 0 and 100 mg L− 1 applied with four levels of ZnO NPs i.e., 0, 25, 50, and 100 mg L− 1.ResultsSeed priming with ZnO NPs had no significant effect on the seed germination (p > 0.05) however, it substantially improved the seedling growth and other related physiological attributes under the Cd stress. The mean fresh weight of the shoot, and whole seedling was increased by 16.92–27.88% and by 16.92–27.88% after ZnO NPs application. The root fresh weight, root-shoot length was also substantially improved under ZnO NPs treatment. Moreover, application of ZnO NPs induced modulations in physiological and biochemical attributes e.g., the superoxide dismutase (SOD) activity in root and shoot, the peroxidase (POD) activity and metallothionein contents in root were increased under low levels of ZnO NPs. The α-amylase and total amylase activity were improved by ZnO NPs application under Cd Stress. Besides, modulation in Zn concentration and ZnO NPs uptake in the seedling were detected. The metabolomic analysis indicated that various pathways such as alanine, aspartate and glutamate metabolism, phenylpropanoid biosynthesis, and taurine and hypotaurine metabolism were possibly important for rice response to ZnO NPs and Cd.ConclusionOverall, application of ZnO NPs substantially improved the early growth and related physio-biochemical attributes in rice. Our findings provide new insights regarding the effects of ZnO NPs on seed germination, and early growth of rice, and its potential applications in developing crop resilience against Cd contaminated soils.
Highlights
Cadmium (Cd) is amongst the most toxic heavy metals that severely affects crop growth, whereas application of nanoparticles (NPs) to negate the toxic effects of heavy metals could be an effective management approach
The concentrations of ZnO NPs and Cd used in this study were based on previous reports [28, 29, 36, 37], which suggested that low dose of ZnO NPs (0–100 mg L −1) may have positive effect of plant growth whilst the Cd treatment with 100 mg L −1 could lead to germination and growth inhibition
The germination and seed vigor index Statistically significant differences (p < 0.05) were noted across varieties (V), and Cd treatments, while differential doses of ZnO NPs treatments did not induce any significant difference in seed germination in both rice varieties
Summary
Cadmium (Cd) is amongst the most toxic heavy metals that severely affects crop growth, whereas application of nanoparticles (NPs) to negate the toxic effects of heavy metals could be an effective management approach. Rice is the staple food for more than four billion people globally and it is cultivated worldwide across different climatic conditions. Cadmium (Cd) is recognized as the most toxic heavy metal, and its concentration in arable lands has increased due to excessive use of agro-chemical and anthropogenic activities [1,2,3]. Dietary intake of plant-derived foods that are rich in toxic metals especially As and Cd poses serious threats to consumers’ health [6]. Rice accounts for ~ 50% of the total Cd intake in people consuming rice as staple food [7]. Minimization of the transfer of Cd from the environment and/or rhizosphere to other plant parts rice grains is important
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