ABSTRACT
Molecular identification and effect of salt-tolerant plant growth-promoting rhizobacteria on the biochemical aspect and growth of rice

Sayma Serine Chompa1, Ali Tan Kee Zuan1*, Adibah Mohd Amin1, Tan Geok Hun1, Amir Hamzah Ahmad Ghazali2, Buraq Musa Sadeq1, Amaily Akter1, Md Ekhlasur Rahman1, 3, and Harun Or Rashid4
 
Soil salinization, a rising issue globally, is a negative effect of the ever-changing climate, which has drawn attention to, and exacerbated problems related to soil degradation and the decline in wetland rice (Oryza sativa L.) production, leading to an unstable national economy. The use of rhizosphere inhabiting microorganisms (plant growth-promoting rhizobacteria, PGPR) is a viable method for boosting agricultural production on saline soils and reduce salt stress in rice crops. The objective of this study was to support the development of rice under salt stress by using a consortium of bacterial strains. ‘Pokkali’ rice plants inoculated with single Bacillus tequilensis and B. aryabhattai isolates were compared with consortium and non-inoculated plants while salinity was increased and by irrigation with tap water (control), 30 mM (5 dS m-1) and 60 mM (10 dS m-1) NaCl. The present study exhibited that inoculation of a mixed inoculum at 5 dS m-1 resulted in significantly higher dry weight of the shoots and roots of seedlings (9.29 and 1.24 g, respectively) which was due to the increased SPAD value, proline content (7.55 µmol g-1 FW), and antioxidant enzyme activity in the inoculated plants. The higher accumulation of osmoprotectants such as proline supported Na+ ion reduction and antioxidant enzymes such as ascorbate peroxidase and reduced polyphenol oxidase content protect against higher cellular damage, eventually leading to increase plant growth performance in saline soil. This study demonstrates some positive effects of the locally isolated salt tolerant consortium PGPR strains on the growth of rice plants under salt stress conditions.
Keywords: Antioxidants, Bacillus tequilensis, Bacillus aryabhattai, Oryza sativa, osmoprotectants, PGPR, plant growth, rice, salinity.
1Universiti Putra Malaysia, Faculty of Agriculture, Serdang 43400, Selangor, Malaysia.
2Universiti Sains Malaysia, School of Biological Sciences, Gelugor 11800, Penang, Malaysia.
3Soil Resource Development Institute, Divisional Laboratory, Krishi Khamar Sarak, Farmgate, Dhaka-1215, Bangladesh.
4Universiti Putra Malaysia, Department of Modern Language & Communications, Serdang 43400, Selangor, Malaysia.
*Corresponding author (tkz@upm.edu.my).