Microbial Inoculation Enhances Growth and Physiological Traits of Tissue Cultured Panicum turgidum Forssk. Plantlets During Acclimatization

Panicum turgidum is an important keystone forage grass crucial for ecosystem stability in arid and semi-arid rangelands of Asia and Africa. This study aimed to investigate the use of beneficial bioinoculants for enhancing the growth and acclimatization of micropropagated desert grass under controlled environmental conditions. Tissue-cultured plants were transferred to pots with a sand–soil mixture (1:1, v/v) and kept in a temperature and light-controlled environment (25 ± 2 °C, 100 µmol m−2·s−1, and 16/8 light/dark photoperiod) for 10 weeks. We used a factorial approach to investigate the effects of the arbuscular mycorrhizal fungus (AMF) Rhizophagus fasciculatus, Trichoderma harzianum, and Bacillus subtilis on transplanted desert grass plants. Two AMF levels control (AMF, 5%; w/w) or without AMF (NAMF); and three microbial inoculation treatments (T. harzianum, B. subtilis, and a combination of T. harzianum + B. subtilis) were employed. Microscopic investigation indicated the extent of AMF colonization in the roots of micropropagated P. turgidum plantlets during acclimatization. Growth parameters with shoots and roots, chlorophyll and carotenoid content, and nitrogen uptake were all improved in bioinoculants-treated plants. Under non-AMF conditions, co-inoculation with T. harzianum and B. subtilis resulted in the highest biomass and root traits, whereas under AMF conditions, T. harzianum alone or with AMF was generally most effective. In the plants treated with the combination of inoculants, heatmap correlation, principal component analysis, and hierarchical clustering demonstrated positive association between growth and physiological traits and the absorption of mineral nutrients, although these associations varied among treatment combinations. These findings highlight the potential of beneficial bioinoculants to improve the growth and acclimatization of micropropagated desert grass plants, providing a foundation for tailored bioinoculant compositions towards the rehabilitation of degraded grazing lands.