Cerium enhances germination and shoot growth, and alters mineral nutrient concentration in rice

Abstract

Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth.

Review of Rare Earth Elements as Fertilizers and Feed Additives: A Knowledge Gap Analysis

“…ROS levels declined after treatment with 0.05 mM La 3+ , and antioxidant metabolism was enhanced. Similar results were found by exposing rice or duckweed to Ce, with an evident shift from stimulating to inhibitory effects by increasing Ce concentrations (Ramírez-Olvera et al 2018;Zicari et al 2018). While the effects of Ce may be species-specific, as measured in eight different plant species, soil properties also can significantly influence the severity of Ce phytotoxicity (Moreira et al 2019).…”

Effects of Ceria Nanoparticles and CeCl3 on Plant Growth, Biological and Physiological Parameters, and Nutritional Value of Soil Grown Common Bean (Phaseolus vulgaris)

“…Many studies have shown that the Ce 3+ ions promote photosynthesis at low doses but become toxic at higher doses. [ 52–58 ] It has been postulated that Ce 3+ may directly influence photosynthesis by replacing the central Mg 2+ from chlorophyll a and forming Ce‐pheophytin a or play an indirect role in chlorophyll formation because Ce 3+ may function as catalysts. [ 58 ]…”

“…The results of previous studies show that at appropriate concentrations, Ce 3+ ions exert a beneficial effect on the growth and development of many plant species, whereas at high concentrations, Ce 3+ ions cause negative effects. [ 55,58,62 ] Fertilizers containing rare earth (with predominant proportion La and Ce) nitrates or chlorides had been used in agriculture to enhance yield of crops and improve the quality of crops in China. [ 52,53 ] However, knowledge on how these elements impact on physiological processes of plants is still fairly limited.…”

Cerium Oxide Nanoparticles Affect Heavy Metals Uptake by Pea in a Divergent Way than Their Ionic and Bulk Counterparts

“…,Tassi et al (2017),Zhang et al (2017),Salehi et al (2018) andRamírez-Olvera et al (2018), respectively. However, to our knowledge, this is the first experimental work on the heavy metal uptake by pea originated by emerging nanopollutants.…”