Plant growth promoting Rhizobacteria: Increase of vegetative and roots biomass in Portulacaria afra

Abstract

In this study, the ability of PGPRs to improve the growth and rooting of Portulacaria afra in pots was evaluated. Portulacaria afra is an interesting plant from a medicinal and ornamental point of view, but it shows some difficulties in the early stages of cultivation. The two experimental groups in cultivation were: i) group without beneficial micro-organisms (CTRL) (peat 60% + pumice 30% + chabazite 10%), irrigated with water and substrate previously fertilized; ii) group with beneficial micro-organisms (PGPR) (peat 60% + pumice 30% + chabazite 10%), irrigated with water and substrate previously fertilized, (1,5g TNC Bactorr S13 per litre of soil). The microorganisms in TNC S13 Bactorr were: Bacillus amyloliquefaciens, B. brevis, B. cirulans, B. coagulans, B. firmus, B. halodenitrificans, B. laterosporus, B. licheniformis, B. megaterium, B. mycoides, B. pasteuri, B. polymixa, B. subtilis (1.3 x 1011 cfu/Kg). All plants treated with Plant Growth Promoting Rhizobacteria (PGPR) showed a significant increase in the agronomic parameters analysed compared to the untreated control (CTRL), both in Portulacaria afra and in Portulacaria afra variegated. The results show that microorganisms are able to improve the absorption of water and nutrients by increasing the agronomic and physiological characteristics of plants. Very interesting aspects to improve agronomic quality, especially for those who cultivate plants from particular environments and that are poorly adapted to our climates and cultivation methods.