Enhancing acclimatization of in vitro raised potato seedlings via biological hardening

Potato is an autotetraploid tuber crop of global significance, widely propagated through tubers. However, conventional propagation methods face challenges such as low multiplication rates and disease susceptibility. Micropropagation via tissue culture enables large-scale production of disease-free plantlets, but high mortality during acclimatization remains a major limitation due to physiological and structural deficiencies. Biological hardening, involving beneficial microorganisms presents a promising strategy to enhance plantlet survival by improving rhizogenesis, nutrient availability, and stress tolerance. In this study, various biological hardening agents like Bacillus subtilis, Pseudomonas flourescens and Trichoderma viride with or without glycerol (0.5%), were tested to identify the optimal combination for maximizing survival rates during acclimatization. Out of all the treatment combinations application of Trichoderma viride along with glycerol (0.5%) gave highest plantlet survival (73.33%) after 3 weeks of acclimatization and all the treatments were found superior to the untreated control. Whereas, maximum increase in plant height was obtained when Bacillus subtilis + Pseudomonas flourescens (consortia) was applied with glycerol (0.5%). The results highlight the effectiveness of microbial inoculation in reducing stress, enhancing growth, and improving the establishment of tissue-cultured potato plantlets. This study underscores the potential of biological hardening as a sustainable approach for improving micropropagation efficiency and large-scale seed tuber production.