Summary
Urbanization and increasing population exert pressure to increase agricultural productivity to feed the increasing population. In order to increase food production, chemical fertilizers are extensively used in agriculture. Plant growth-promoting rhizobacteria (PGPRs) increase soil fertility and plant health. The present study was aimed to study the effect of five carbohydrates: sucrose, inulin, kappa-carrageenan, alginate and iota-carrageenan on growth of Ensifer fredii, Serratia proteamaculans and Pseudomonas fluorescens CHAO, and their role in plant growth promotion. The results presented in this study showed that inulin and kappa carrageenan improved the growth of the PGPRs (Ensifer fredii, Serratia proteamaculans and Pseudomonas fluorescens CHAO).
This project aims to explore the effect of different saccharides as substrates to selectively enhance the beneficial bacteria in the soil, and how those bacteria effect on plant growth. To do this, we set two experiments, Experiment 1 proofed that the population of PGPRs changes under the stimulation of carbohydrates. Finally, in order to detect the effect of carbohydrate on the enhancement of PGPRS in soil, experiment 2 further simulated the changes in the number of PGPRs under the premise of the soil surrounding.
The excessive use of chemical fertiliser poses threat to ecosystem including microbial diversity in the soil. The population of the PGPR mainly depends on the plant’s root exudates, having a clear effect in the recruitment of beneficial species of bacteria and fungi. Therefore, the potentiation of root exudates by the supplementation of the carbohydrates could enhance the colonization of PGPRs. In this study, the effects of inulin and kappa-carrageenan on the proliferation of PGPRs (Ensifer fredii, Serratia proteamaculans and Pseudomonas fluorescens CHAO) were particularly prominent. The application of bio-stimulants prepared from these carbohydrates provides an environmentally safe and sustainable method for the plant growth promotion by enriching the beneficial microbiota of the soil. The results presented here are promising but to realize the full potential of these carbohydrates in stimulating plant’s PGPR diversity, a more comprehensive research is required.