Seed functional traits, tetrazolium viability optimization, and storage behaviour of three native bignoniaceae tree species

Abstract

Seed functional traits strongly influence hydration behaviour, viability expression, germination performance, and storage responses in tropical tree species, yet comparative information for many native Bignoniaceae taxa remains limited. This study evaluated seed morphology, imbibition kinetics, tetrazolium (TZ) viability optimization, germination behaviour, and short-term storage responses of three native Indian Bignoniaceae trees— Dolichandrone falcata , Radermachera xylocarpa , and Stereospermum chelonoides . We hypothesized that differences in seed structural traits would influence hydration dynamics, TZ staining behaviour, and post-storage viability responses. Morphometric analysis revealed clear interspecific differences in seed size and structure, with R. xylocarpa producing the largest membranous seeds, D. falcata exhibiting intermediate-sized corky seeds, and S. chelonoides producing comparatively smaller seeds. Distinct imbibition patterns were observed among species, including rapid triphasic hydration in R. xylocarpa , moderate permeability in D. falcata , and prolonged gradual hydration in S. chelonoides . Species-specific variation in seed structural traits significantly influenced hydration kinetics, tetrazolium staining behaviour, and germination responses, indicating strong trait–function relationships relevant to seed functional ecology and viability diagnostics. TZ concentration, staining duration, and their interaction significantly affected viability estimates ( p < 0.001), with maximum viability recorded in S. chelonoides (up to 99.38%). Regression-based interpretation further suggested that seed coat structure and hydration dynamics strongly influence viability expression and germination performance. Seeds tolerated desiccation to approximately 5% moisture content and maintained viability after storage at − 20 °C for three months, indicating preliminary orthodox storage behaviour under short-term low-temperature storage conditions. The findings demonstrate that uniform seed testing protocols may be unsuitable even among related taxa and highlight the importance of integrating seed structural traits with physiological assessment for improving viability testing, nursery propagation, and ex situ conservation strategies.