**6.2 Combined effects of biochar and plant growth-promoting bacterial endophytes on alleviating salt stress in maize**

Employing the salt tolerant PGPR to enhance crop productivity has been a sustainable and efficient method [119–122]. Researchers have documented that PGPR produced the exopolysaccharide (EPSs) that prevent the uptake of Na + ions by sequestering these ions [123, 124]. Studies demonstrated that few PGPR have an important enzyme, ACC- deaminase, which can reduce ethylene production by metabolizing ACC into ammonia. ACC is the precursor of ethylene and a-ketobutyrate [125–127]. Unlike PGPR, plant growth-promoting bacterial endophytes colonize the internal tissues of plants without causing any harm to the plants [128]. It can lead to several physiological modifications that contribute to plant growth and development [129–131]. These, plant growth-promoting bacterial endophytes may promote plant growth by adopting the similar mechanisms as observed in PGPR [132]. Thus, it is proved that plant growth-promoting bacterial endophytes are more effective in promoting plant growth even under severe stresses as compared to PGPR. Different researchers have demonstrated that for reducing soil salinity addition of biochar along with endophytic bacteria is an efficient and environment friendly approach [133].

For enhancing crop growth and yield, use of biochar is cost effective and eco-friendly option to boost water and nutrient-holding capacity of soil [134–137]. Application of biochar has positive effects on physicochemical properties of soil. Moreover, Biochar can also improve a variety of soil microbes by providing them a favorable habitat and nourishment [138]. Thus, it is an excellent solution for recycling organic waste and solution to environmental pollution.

There are three important mechanisms underlying biochar-mediated reduction of salt stress in plants. These include:


### **7. Conclusion**

Reclamation of saline soils is mainly achieved by employing various physicochemical processes. However, these processes are not sustainable and considered inefficient in the case of high salt concentration. PGPR contain a vital enzyme, 1-aminocyclopropane-1-carboxylate deaminase that can decrease salinity induced ethylene production. Silicon and elemental sulfur can also be applied to reduce the negative effects of soil salinity on plants. The organic matter such as press mud usually contains about 70% lime, 15–20% organic matter and 23% sugar. This organic

**125**

**Author details**

Pakistan

Sajid Rashid Ahmad\*, Sana Ashraf\* and Humaira Nawaz

provided the original work is properly cited.

College of Earth and Environmental Sciences, University of the Punjab, Lahore,

\*Address all correspondence to: sajidpu@yahoo.com and sana.cees@pu.edu.pk

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Interactive Effect of Organic and Inorganic Amendments along with Plant Growth Promoting…*

matter is highly soluble and readily available to the microbial activity and soil. Due to microbial activity more carbon dioxide is produced that may increase the solubility of lime and hence reclaim the saline soils. Hence, the combine application of organic amendments (like press mud), inorganic amendments (like silicon and elemental sulfur) and PGPR can ameliorate the saline soil in an environmentally

*DOI: http://dx.doi.org/10.5772/intechopen.99063*

The authors declare no conflict of interest.

sustainable way.

**Conflicts of interest**

*Interactive Effect of Organic and Inorganic Amendments along with Plant Growth Promoting… DOI: http://dx.doi.org/10.5772/intechopen.99063*

matter is highly soluble and readily available to the microbial activity and soil. Due to microbial activity more carbon dioxide is produced that may increase the solubility of lime and hence reclaim the saline soils. Hence, the combine application of organic amendments (like press mud), inorganic amendments (like silicon and elemental sulfur) and PGPR can ameliorate the saline soil in an environmentally sustainable way.
