Optimised fertilisation with zeolitites containing Plant Growth Promoting Rhizobacteria (PGPR) in Ranunculus asiaticus

Abstract

In this study, the possibility of optimizing the use of fertilizers on Ranunculus asiaticus by adding chabazite with Plant Growth Promoting Rhizobacteria (PGPR) to the substrate was evaluated. The five experimental groups in cultivation were: i) group without zeolites (CTRL), irrigated with water and substrate previously fertilized; ii) group with natural chabazite (CN) and 100% fertilised substrate; iii) group with chabazite enriched with PGPR (CM) and 100% fertilised substrate; iv) group with natural chabazite (CN2) and 50% fertilised substrate; v) group with chabazite enriched with PGPR (CM2) and 50% fertilised substrate. All plants treated with chabazite (CN and CN2) and chabazite enriched with PGPR (CM and CM2) showed a significant increase in the agronomic characteristics analysed compared to the untreated control (CTRL). The results show that the microorganisms are able to improve the performance of zeolitite, probably increasing the efficiency of nutrient and water absorption by the roots. This is also evident when evaluating physiological parameters where the photosynthesis rate and chlorophyll content are significantly better in (CM) and (CM2) than in (CN) and (CN2). Zeolites can act as a "home" for microorganisms, as is normally the case in nature with clays. In fact, under conditions of water stress, microorganisms take refuge inside the clay particles until the environmental conditions are suitable again to colonize the soil. Zeolites are able to actively interact with the organic components present in the soil or brought with fertilization, and have the ability to make more available the mineral and nutritional components present within their crystalline lattice, according to the needs of the plant.