The effect of mycorrhizal fungi and bacterial endosymbionts on the productivity of raspberry plants under water-stressed conditions

Abstract

Goal. A study investigating the impact of a multicomponent, multifunctional inoculation comprising mycorrhizal fungi (Trichoderma and Glomus species) and bacteria (Agrobacterium) on the growth and productivity of raspberry plants (Rubus idaeus L.) under abiotic stress conditions (drought).

Methods. The research was conducted in open ground conditions at the experimental site of the Institute of Agrobiology LLC in Vysoke village, Brusyliv district, Zhytomyr region, from 2023 to 2025. The experimental plantings were cultivated using the Ukrainian-bred raspberry variety ‘Vognik’. The research design involved combinatorial inoculation of the fungi Trichoderma spp. and Glomus sp. and the bacteria Agrobacterium radiobacter into the rhizosphere of the plants via fertigation, under different soil moisture conditions: sufficient (80 ± 5% field capacity (FC)), moderate drought (50% FC) and severe drought (30% FC). General scientific and special methods were employed, including field, laboratory and statistical methods. The fungal strains (Trichoderma viride eko/103, T. harzianum eko/101 and Glomus sp. eko/104) were obtained from the Institute of Agrobiology LLC’s culture collection, while the Agrobacterium radiobacter bacteria were isolated directly by the authors.

Results. Field trials involving the inoculation of raspberry plants with Trichoderma and Glomus fungi and Agrobacterium bacterial symbionts demonstrated improvements in the plants’ overall condition and increased their resistance to stress under soil drought conditions. This reduced the leaf surface temperature by 5.8—11.2%, promoted the activation of photosynthesis and increased the content of chlorophylls «a» and «b» by 16.6—60.8%. It also increased productivity, with the weight of fruit per bush increasing by 1.08—1.27 times and the weight of a single berry by 13.5—33.3%. The final crop yield increased by 8.8—16.6% under various conditions of moisture deficiency.

Conclusions. The combined inoculation of mycorrhizal fungal consortia and bacterial endosymbionts — Trichoderma  spp., Glomus sp. and Agrobacterium radiobacter — has a positive effect on the productivity parameters of Rubus idaeus L. raspberries compared to the control (untreated) group in conditions of moisture deficiency. This symbiotic effect of the three-way microbial consortium with the R. idaeus L. rhizosphere is due to the microorganisms’ synergistic action in a multicomponent system and their mutual influence. These findings are of practical importance for enhancing the efficiency of raspberry cultivation in open ground.