Impact of cryopreservation on pollen viability and morphological integrity of five Indian Crinum species.

Crinum species are ornamental plants of high horticultural value and medicinal importance, known for their bioactive alkaloids with neurological and anticancer properties. Sustainable use and genetic conservation of Crinum require reliable long-term germplasm conservation strategies, and pollen cryopreservation offers an effective approach by enabling year-round breeding and conservation independent of seasonal and geographic constraints. This study presents the first species-comparative evaluation of pollen germination behaviour and cryopreservation responses in five ecologically contrasting Indian Crinum species (C. asiaticum, C. latifolium, C. malabaricum, C. lorifolium and C. viviparum). In vitro pollen germination treatments with varying sucrose (1-10 %) and polyethylene glycol (PEG) concentrations were optimized, species-specific critical moisture contents were determined, and pollen viability was assessed before and after cryostorage at -196 °C for up to 180 days. Distinct, habitat-linked germination responses were observed: aquatic and semi-aquatic species achieved optimal germination (>91 %) only under PEG-mediated osmotic regulation, whereas terrestrial species performed best in sucrose-only treatments. Precise moisture content ranges (12-18 %) were identified as critical for maximizing post-cryopreservation viability, with small deviations resulting in marked germination loss. Cryopreserved pollen retained high functional competence, with minimal viability decline (<5 %) after 180 days, and scanning electron microscopy revealed only minor, non-critical ultrastructural changes. By linking pollen osmotic sensitivity, ecological adaptation, and cryotolerance within a single genus, this study advances pollen cryobiology beyond empirical optimization and provides biologically informed, species-specific protocols for pollen cryobanking. These findings strengthen the scientific basis for ex situ conservation, germplasm exchange, and breeding programmes targeting horticultural and medicinal improvement of Crinum species.