Superiority of modified graphene oxide for enhancing the growth, yield, and antioxidant potential of pearl millet (Pennisetum glaucum L.) under salt stress

Abstract

Soil salinity is a serious global problem that affects the vegetative growth and photosynthesis rates of plants. Additionally, a high salinity facilitates the accumulation of free radicals and reactive oxygen species (ROS), which induces an increase in the malondialdehyde, hydrogen peroxide, and proline contents, and a decrease in the antioxidant activity of enzymes, such as superoxide dismutase and peroxidase, reducing the fodder yield. Owing to limited availability of forage crops, extensive efforts have been devoted to studying the pearl millet (Pennisetum glaucum L.) plant, which is employed as a protein-rich fodder crop in its green and dry forms. Therefore, a field experiment was conducted to explore the effect of graphene oxide, methionine, lysine, methionine@graphene oxide, and lysine@graphene oxide on the growth, biomass accumulation, photosynthetic pigment content, total protein content, oxidative stress, and antioxidant response of the pearl millet plant. Modified graphene oxide (20 mg L−1) was applied two times to the fresh leaves of pearl millet after 30 and 60 days of cultivation. The salt concentrations in the soil and water in the area under consideration were 3.16 d.Sm−1 and 10.29 d.Sm−1, respectively. The treatments induced a significant improvement in plant growth, biomass accumulation, total protein content, photosynthetic pigment content, and yield. Similarly, the generation of ROS was reduced in the plant cells/tissues compared to the case in the plants grown under saline conditions. The foliar application of both graphene oxide and its modified structures enhanced the salinity stress tolerance of pearl millet by modulating its morphological and biophysical traits. This study offers new possibilities for the application of modified materials in agriculture and provides a valuable basis for improving plant tolerance and adaptability to salinity stress.