Exploring the use of Leucobacter komagatae as an eco-friendly bio-inoculant to enhance sugarcane (Saccharum officinarum) growth and yield under drought conditions.

Abstract

Drought occurrence owing to climate change is a major constraint to attain sustainable agriculture, severely limiting crop growth and productivity. Sugarcane (Saccharum spp. hybrids), a key crop in tropical and subtropical regions, is particularly susceptible to drought stress because of its extended growth duration and high-water requirements. In this study, previously identified four plant growth promoting Leucobacter komagatae (ASBD2, ASBD15, ASBD19 and ASBD30) were evaluated under greenhouse conditions (pot culture study) over two consecutive years (2023-24 and 2024-25). Of these four isolates, L. komagatae ASBD19 showed the strongest performance for several physiological and drought-response attributes, whereas ASBD2 and ASBD15 were more effective for biomass accumulation and nutrient acquisition, respectively. The ASBD 19 strain exhibited significantly enhanced germination rate (70% and 66% at 60 days after planting (DAP)), tillering ( 8 and 9 tillers/pot at 180 days), plant height (118 cm and 127 cm at 270 days), photosynthetic activity at grand growth stage (PAR incident on leaf surface 1150.7 µmol m-² s-¹ ; transpiration rate 3.85 mol m-² s-¹; photosynthetic rate 18.15 µmol m-² s-¹; and stomatal conductance 0.93 mol m-² s-¹), and increased cane length (165 cm and 168 cm) and cane weight (0.75 and 0.54 kg) at harvesting stage of the sugarcane compared to the control under drought stress. In conclusion, these findings suggest that the native L. komagatae strains have potential as sustainable bioinoculants for drought-prone sugarcane, with ASBD19 for maintaining physiological performance and drought adaptation, whereas ASBD2 and ASBD15 for improving nutrient acquisition and biomass production.