PGPR and PGPF Mediated Seed Bio-priming for Improving Seed Germination and Early Seedling Growth in Acer oblongum (Himalayan Maple)

Abstract

Background: Acer oblongum (Himalayan maple) is an ecologically and socio-economically important Himalayan tree species. Poor natural regeneration and inconsistent seed germination in its natural habitats constrain its propagation, conservation, and nursery-scale multiplication. Aim: The present study aimed to evaluate the effects of plant growth-promoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF), used as seed bio-priming agents, on germination percentage and early seedling vigour of A. oblongum under in vitro conditions. Study Design: The study was conducted using a completely randomised design (CRD) to evaluate the effects of microbial treatments on germination percentage, mean germination time, germination value, peak value, germination index, root length, shoot length, and total seedling length. In vitro analyses were performed using the selected PGPR and PGPF isolates. The experiment comprised seven treatments: an untreated control, P. gessardii, P. mosselii, P. fluorescens, B. subtilis, a bacterial consortium, and Trichoderma spp. Bio-primed seeds were incubated in a germinator, and germination was monitored daily throughout the experimental period. Results: Microbial treatments significantly affected germination parameters and early seedling performance. The highest germination percentage was observed in seeds treated with Trichoderma (38.40%), followed by Pseudomonas mosselii (34.40%), compared with the control (28.00%). Root length, shoot length, collar diameter, and seed vigour index were highest in seeds treated with Trichoderma, followed by the consortium, compared with the control. Conclusion: Among the tested treatments, Trichoderma spp. was the most effective and produced the highest germination percentage, germination value, peak value, germination index, root length, shoot length, total seedling length, and seed vigour index in Acer oblongum.