Thermal Evaluation Of Microbial Consortia For Drought Tolerance In Lettuce

Increased water scarcity represents a significant threat to global lettuce production, reducing crop quality and yield. While producers often resort to overfertilization to mitigate water stress, biological alternatives such as microbial inoculants offer a more sustainable approach. This study evaluated the effectiveness of a 67-strain microbial consortium and a Trichoderma harzianum isolate in enhancing water stress tolerance in Romaine lettuce (Lactuca sativa var. Paspartu) under controlled conditions. Nine treatments were established, combining microbial inoculation with three irrigation levels (50%, 75%, and 100% of evapotranspiration). Crop water status was monitored using infrared thermography to calculate the Crop Water Stress Index (CWSI) from fluctuations in canopy temperature (Tc). The statistical analysis (ANOVA) of the CWSI showed no globally significant differences between treatments (F = 0.67, p = 0.778); however, distinct numerical trends were observed during peak thermal stress events. Under severe water deficit (50% irrigation), plants inoculated with the microbial consortium maintained lower CWSI values (averaging 0.38) compared to non-inoculated controls, which reached maximum stress thresholds (CWSI = 1.0). Furthermore, microbial treatments demonstrated a faster thermal recovery following acute stress periods. These results suggest that while global variance is high, microbial consortia function as physiological buffers that enhance transpiration efficiency. Infrared thermography proved to be a precise, non-destructive tool for early detection of water stress. This study highlights the potential of beneficial microorganisms to improve crop resilience and provides a standardized protocol for thermal evaluation in horticultural research.