Effect of Foliar Spraying of Gibberellins and Brassinolide on Cadmium Accumulation in Rice

Abstract

Cadmium (Cd) is one of the heavy metals that contaminate rice cultivation, and reducing Cd contamination in rice through agronomic measures is a hot research topic. In this study, foliar sprays of gibberellins (GA) and brassinolide (BR) were applied to rice under Cd stress in hydroponic and pot experiments. After foliar spraying of GR and BR, the biomass of rice plants grown in either hydroponics or soil culture was significantly higher or even exceeded that in the absence of Cd stress. In addition, photosynthetic parameters (maximum fluorescence values), root length and root surface area, and CAT, SOD and POD activities were significantly improved. The MDA content decreased in the shoots, suggesting that the application of GR and BA may have enhanced photosynthesis and antioxidant function to alleviate Cd stress. Furthermore, the BR and GA treatments decreased the Cd content of rice roots, shoots and grains as well as the Cd transfer coefficient. Cd chemical morphology analysis of rice roots and shoots showed that the proportion of soluble Cd (Ethanol-Cd and Water-Cd) decreased, whereas the proportion of NaCl-Cd increased. Analysis of the subcellular distribution of Cd in rice roots and above ground showed that the proportion of Cd in the cell wall increased after foliar spraying of GA and BR. The results indicate that after foliar application of GA and BR, more of the Cd in rice was transformed into immobile forms and was fixed in the cell wall, thus reducing the amount in the seeds. In summary, foliar sprays of GA and BR can reduce the toxic effects of Cd on rice plants and reduce the Cd content in rice grains, with GA being more effective.

Citric Acid Inhibits Cd Absorption and Transportation by Improving the Antagonism of Essential Elements in Rice Organs

“…Research has shown that the addition of organic acid supplements could decrease Cd content in vacuoles, and, through enhancing the isolation of Cd by root vacuoles, thus contribute to maintaining plant growth and reducing Cd content [ 17 ]. The foliar application of inhibitors could reduce the transport of Cd from rice roots and stem bases to other parts by altering grain quality and lowering rice Cd content [ 41 ]. Additionally, when faced with heavy metal stress, CA may protect plant cell-structure integrity and stability by restoring ion balance within the plant.…”

Novel Insights into Exogenous Phytohormones: Central Regulators in the Modulation of Physiological, Biochemical, and Molecular Responses in Rice under Metal(loid) Stress

“…The interaction of Fe with Br28 and Br24 changed the Cd and As contents to a more reduced level in rice grains, suggesting that the use of Br28 and Br24 in combination with Fe is an effective way of reducing Cd and As contents in grains of rice [94]. Foliar spraying of brassinolide on rice plants under Cd stress resulted in increased root length and root surface area, and CAT, SOD, and POD activities were significantly improved, and the Cd content of rice was decreased by transforming Cd into immobile forms and fixing in the cell wall [95]. The application of Br24 decreased the rice growth but applying IP (iron plaque) in combination with Br24 increased its growth.…”

The effect of several growth regulators and biostimulant on biochemical and physiological changes in acclimation of micropropagated Echinacea purpurea Moench. ‘Raspberry Truffle’

“…Exogenous application of 24-epiBL increased the activity of antioxidant enzymes such as CAT to overcome the toxic effects caused by Pb of Brassica juncea seedlings (Santos NeriSoares et al 2020). Rice growing in Cd stress whereas application of BR resulted in growing CAT activity(Li et al 2023). Application of PBs caused a slight improvement in antioxidant activities in maize and soybean plants(De Vasconcelos et al 2009).…”