Mitigation of drought stress in chili plants (Capsicum annuum L.) using mango fruit waste biochar, fulvic acid and cobalt

Abstract

Drought stress can have negative impacts on crop productivity. It triggers the accumulation of reactive oxygen species, which causes oxidative stress. Limited water and nutrient uptake under drought stress also decreases plant growth. Using cobalt and fulvic acid with biochar in such scenarios can effectively promote plant growth. Cobalt (Co) is a component of various enzymes and co-enzymes. It can increase the concentration of flavonoids, total phenols, antioxidant enzymes (peroxidase, catalase, and polyphenol oxidase) and proline. Fulvic acid (FA), a constituent of soil organic matter, increases the accessibility of nutrients to plants. Biochar (BC) can enhance soil moisture retention, nutrient uptake, and plant productivity during drought stress. That's why the current study explored the influence of Co, FA and BC on chili plants under drought stress. This study involved 8 treatments, i.e., control, 4 g/L fulvic acid (4FA), 20 mg/L cobalt sulfate (20CoSO₄), 4FA + 20CoSO₄, 0.50%MFWBC (0.50 MFWBC), 4FA + 0.50MFWBC, 20CoSO₄ + 0.50MFWBC, 4FA + 20CoSO₄ + 0.50MFWBC. Results showed that 4 g/L FA + 20CoSO₄ with 0.50MFWBC caused an increase in chili plant height (23.29%), plant dry weight (28.85%), fruit length (20.17%), fruit girth (21.41%) and fruit yield (25.13%) compared to control. The effectiveness of 4 g/L FA + 20CoSO₄ with 0.50MFWBC was also confirmed by a significant increase in total chlorophyll contents, as well as nitrogen (N), phosphorus (P), and potassium (K) in leaves over control. In conclusion4g/L, FA + 20CoSO₄ with 0.50MFWBC can potentially improve the growth of chili cultivated in drought stress. It is suggested that 4 g/L FA + 20CoSO₄ with 0.50MFWBC be used to alleviate drought stress in chili plants.

Keywords: Activated carbon; Antioxidants; Chlorophyll content; Growth attributes; Nutrients concentration; Organic amendment; Osmotic stress.

Figure 1

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄) with and without mango fruit waste biochar (MFWBC) on plant height, plant dry weight, and no. of primary branches/plant of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.

Figure 2

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄) with and without mango fruit waste biochar (MFWBC) on fruit length, fruit girth, and fruit yield of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.

Figure 3

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄) with and without mango fruit waste biochar (MFWBC) on chlorophyll a, chlorophyll b, and total chlorophyll of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.

Figure 4

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄)with and without mango fruit waste biochar (MFWBC) on peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.

Figure 5

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄) with and without mango fruit waste biochar (MFWBC) on electrolyte leakage, proline, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) (D) of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.

Figure 6

Effect of 4 g/L fulvic acid (4FA) and 20 mg/L cobalt sulfate (20CoSO₄) with and without mango fruit waste biochar (MFWBC) on leaves N, leaves P, leaves K, and leaves Na of chili plants. The bars (n = 4 average) with ± S. denoted with distinct letters showed significant changes at p ≤ 0.05.