Biochar Amendment in Combination with Endophytic Bacteria Stimulates Photosynthetic Activity and Antioxidant Enzymes to Improve Soybean Yield Under Drought Stress

Abstract

The beneficial effects of biochar (BC) and plant growth-promoting bacteria (PGPR) to increase crop yields under harsh environments have been widely reported. However, the knowledge on the synergistic effects of BC and PGPR to induce drought tolerance in oilseeds is scant. In the present study, the effects of cotton sticks derived BC together with PGPR strains (Paraburkholderia phytofirmans and Bacillus sp.) were examined in water-stressed soybean plants. Initially, the BC application rates (1% and 2%) for soybean were optimized in a pilot experiment (experiment I), and the most effective level (1%) was selected for further studies together with PGPR in the second experiment. The soybean plants were raised in pots under semi-controlled conditions and were subjected to drought stress (25–30% water holding capacity) at pod formation stage. In comparison with control, the drought-mediated decrease in photosynthetic pigments and gas exchange characteristics was markedly lower in BC and PGPR-treated plants. However, the maximum increase in photosynthetic (12–30%) and the enzymatic antioxidant activities (5–20%) was recorded in plants treated with BC + P. phytofirmans, whereas no further significant increase was observed in plants treated with combined BC and Bacillus sp. under water deficit conditions. Similarly, the combined BC and P. phytofirmans application considerably increased the grain yield (14%) under drought stress conditions. We conclude that the combined application of BC + P. phytofirmans could be utilized as an effective strategy to improve soybean yield in dry arid regions.

Salt stress amelioration and nutrient strengthening in spinach (Spinacia oleracea L.) via biochar amendment and zinc fortification: seed priming versus foliar application

“…The use of biochar has shown a significant improvement in the activities of antioxidant enzymes. The results are consistent with the research conducted by Nawaz et al 78 and Kumari and Malaviya et al 79 which showed that biochar can enhance the activities of antioxidant enzymes, hence strengthening the plant’s ability to defend against oxidative stress. Moreover, nanoparticles, as explored by Adrees et al 80 and Hussain et al 81 , have been shown to enhance the activities of antioxidant enzymes in wheat plants.…”

Seed Treatment with Sodium Nitroprusside Ensures a Long-Term Physiological and Protective Effect on Wheat under Salinity

“…Thus, treatment with 200 µM SNP reduces the negative impact of salinity on the content of photosynthetic pigments (Figures 4 and 7). It is known that an increase in the content of photosynthetic pigments lead to an increase in plant biomass and productivity [45][46][47]. This is supported by the data in Table 3.…”

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

“…PGPMs have shown particular promise in combination with biochar in agricultural applications [ 49 , 50 ]. Combining biochar with PGPMs has been demonstrated to be of benefit to plants under drought stress, such as French beans [ 51 ], cucumber [ 52 ], maize [ 53 ], soybeans [ 54 ], and a range of other crops [ 55 ]. Prior research has also been conducted on the combination of biochar with compost [ 56 , 57 ], compost tea [ 58 ], and sewage sludge [ 10 ], which facilitate broad-spectrum microbial inoculation of biochar.…”