Effect of actinobacterial metabolites on root growth of cereal crops in the context of environmentally safe technologies

Actinobacteria are promising producers of biologically active compounds capable of either stimulating or inhibiting plant growth. Understanding their interactions with agricultural crops is essential for developing safe biopreparations that reduce the reliance on chemical fertilizers and pesticides, thereby aligning with the principles of sustainable agriculture and soil conservation.

The aim of this study was to evaluate the effects of a soil-derived actinobacterial strain suspension and its extracted pigment on root formation in brewing barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.) under laboratory conditions.

Seeds were soaked in either the bacterial suspension or the pigment solution; distilled water served as the control. Root length was measured over 14 days.

The results showed that the actinobacterial suspension significantly inhibited root growth in both crops (barley: days 1-4; wheat: days 8-14) (Student's t-test, p < 0.05). In contrast, the pigment extracted from the same culture exhibited a mild but consistent stimulatory effect on barley, with root length reaching 141.7 ± 8.53 mm by day 8 versus 123.2 ± 17.47 mm in the control. For wheat, the pigment's effect was less stable: a slight early stimulation was followed by a moderate growth lag by day 14 (152.5 ± 22.93 mm vs. 165.7 ± 12.94 mm in the control), although these differences were not statistically significant (p > 0.05).

These findings demonstrate that a single microbial strain can produce metabolites with opposing biological activities. This opens up prospects for isolating environmentally benign growth promoters while also highlighting the need for species- and variety-specific approaches when formulating biopreparations. This study contributes to the development of green technologies in agroecosystems, reducing anthropogenic pressure on soils and supporting ecological sustainability in crop production.