Calcium-Rich Biochar Stimulates Salt Resistance in Pearl Millet (Pennisetum glaucum L.) Plants by Improving Soil Quality and Enhancing the Antioxidant Defense

Kamal A M Abo-Elyousr; Magdi A A Mousa; Omer H M Ibrahim; Nouf Owdah Alshareef; Mamdouh A Eissa

doi:10.3390/plants11101301

Calcium-Rich Biochar Stimulates Salt Resistance in Pearl Millet (Pennisetum glaucum L.) Plants by Improving Soil Quality and Enhancing the Antioxidant Defense

Plants (Basel). 2022 May 13;11(10):1301. doi: 10.3390/plants11101301.

Authors

Kamal A M Abo-Elyousr¹, Magdi A A Mousa¹, Omer H M Ibrahim¹, Nouf Owdah Alshareef², Mamdouh A Eissa³

Affiliations

¹ Department of Arid Land Agriculture, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah 80208, Saudi Arabia.
² Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 80208, Saudi Arabia.
³ Department of Soils and Water, Faculty of Agriculture, Assiut University, Assiut 71526, Egypt.

Abstract

Shrimp waste is rich in organic compounds and essential plant nutrients, e.g., calcium (Ca), and converting these wastes to organic fertilizer is important for environmental preservation and to achieve sustainable agricultural management. In the current study, Ca-rich biochar was prepared from shrimp wastes (SWB) by pyrolysis at 300 °C. We hypothesized that the Ca-rich biochar will help in solving the problem of plant growth in saline soil by reducing sodium (Na) uptake and mitigating oxidative stress. The current study aimed to investigate the effect of SWB on the quality of saline sandy soil and the mechanism of salt resistance in pearl millet (Pennisetum glaucum L.). Pearl millet plants were planted in saline sandy soil (10 dS m^-1) in wooden boxes (1.3 × 0.8 m size and 0.4 m height), and 5 doses (0, 1.0, 1.5, 2.0, and 2.5% (w/w)) of SWB were added. SWB application increased the soil quality and nutrient uptake by pearl millet plants. The highest rate of SWB increased the soil microbial biomass carbon and the activity of dehydrogenase enzyme by 43 and 47% compared to the control soil. SWB application reduced the uptake of sodium (Na⁺) and chloride (Cl^-) and increased the K/Na ratio in the leaf tissues. SWB addition significantly increased the activity of antioxidant enzymes, e.g., ascorbate peroxidase (APX), polyphenol oxidase (PPO), and pyrogallol peroxidases (PPX). The application of 2.5% SWB to the saline soil increased the soluble carbohydrates and proline in plant leaves by 75 and 60%, respectively, and reduced the malondialdehyde (MDA) by 32% compared to the control. SWB enhanced the antioxidant defense and mitigated oxidative stress by improving the synthesis of osmoprotectants, e.g., soluble carbohydrates and proline. Sandy saline soils in arid and semiarid areas suffer greatly from low organic matter contents, which reduces the soil quality and increases the risk of salt during plant growth. The high organic matter and calcium content (30%) in the shrimp waste-derived biochar improved the quality of the saline sandy soil, reduced the uptake of toxic salts, and increased the quality of the forage material. The addition of recycled shrimp waste to saline low-fertility soils improves soil productivity and is safe for soil health.

Keywords: Pennistum glaucum; antioxidant enzymes; leaf biochemical; nutritive value; sandy soils.

Grants and funding

This research was funded by the Deputyship for Research & Innovation, Ministry of Education in Saudi Arabia for funding this research work through the project number “IFPHI-348-155-2020”.