Effects of a microbial plant biostimulant on soil microbial activity, photosynthetic performance, and grain productivity of winter wheat under greenhouse conditions

Year 2026, Volume: 15 Issue: 1, 90 - 101, 02.01.2026

Benedict Okorie , Katya Petkova Dimitrova Dobrinka Anastasova Balabanova

https://doi.org/10.18393/ejss.1833761

Abstract

Plant biostimulants are widely recognized as an eco-friendly alternative to chemical fertilizers due to their beneficial effects on soil health and plant growth. This study evaluated the effects of a microbial plant biostimulant on soil microbial activity, photosynthetic performance, and grain productivity of winter wheat grown under greenhouse conditions. Four treatments were tested: control (C), microbial plant biostimulant (MPB, 1 kg/ha), chemical fertilizer (CF, 100 kg/ha), and combined application (CF+MPB, CF dose reduced by 25%). The experiment used winter wheat variety KWS Lazuli and each treatment comprised six replications at completely randomized design. Studied parameters included soil chemical analysis, microbial metabolic activity, photosynthetic performance, and wheat grain productivity. The results showed that application of microbial plant biostimulant (MPB) did not affect soil chemical composition but increased soil dehydrogenase activity. Microbial plant biostimulant (MPB) also affected plant growth parameters and grain productivity. The combined application (CF+MPB) showed no synergistic effects and for net photosynthetic rate and grain productivity did not exceed the results obtained with the CF. However, the overall positive trend across studied parameters supports further research on the partial replacement of chemical fertilizers with microbial plant biostimulants under field conditions.

Keywords

Grain productivity , microbial biostimulant , soil microbial activity , photosynthetic performance , winter wheat

Supporting Institution

Agricultural University – Plovdiv

Project Number

Project 03/23

Thanks

This work was part of the MSc thesis for the Erasmus Mundus Masters in Soil Science and was financially supported by the Centre for Science Research, Technology Transfer, and Protection of Intellectual Property at the Agricultural University – Plovdiv, Project 03/23. Special thanks are extended to Professor Andon Vassilev for invaluable help and guidance during the experimental work. Gratitude is also expressed to Agredo EOOD, Bulgaria, for supplying microbial plant biostimulant used in the study.

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