Can Biostimulants and Phytohormones Improve Early Growth, Biomass Allocation, and Photosynthesis in Miscanthus Plug Plants?

ABSTRACT Seed‐based propagation of Miscanthus offers scalable potential for expanding bioenergy production; however, early establishment remains a major limitation due to poor plug vigour and variable field performance. This study evaluated the influence of selected biostimulants and phytohormones on germination, growth, biomass allocation, and photosynthetic efficiency in three Miscanthus seed‐based hybrids (GNT3, GNT14, and GNT43) grown under controlled glasshouse conditions. Five treatments were applied—Liquid Ice, MicroPull, indole‐3‐acetic acid (IAA), 1‐naphthaleneacetic acid (NAA), and an untreated control—during the plug phase. ANOVA revealed strong hybrid‐dependent responses. Liquid Ice and IAA significantly enhanced stem elongation, total biomass, and photosynthetic capacity (rETR max , I k ), while also shifting biomass allocation toward above‐ground structures. MicroPull, in contrast, delayed germination and reduced photosynthetic parameters in certain hybrids, though it improved initial quantum yield (α) at low light intensities. Enhanced root and bud development under Liquid Ice and NAA treatments suggests improved plug vigour and potential for stronger field establishment. The observed morphological and physiological modifications indicate that targeted PGR use can simultaneously enhance early growth, resource allocation, and photosynthetic performance in Miscanthus . Additionally, the findings highlight the importance of hybrid‐specific optimization of PGR regimes to improve plug quality and establishment success, advancing the scalability of seed‐based Miscanthus systems for sustainable bioenergy production and net‐zero carbon targets.