Effect of cryopreservation on pollen viability, fertility and morphology of different Psidium species

Cryopreservation of pollen is a complementary conservation strategy and can be used for conserve the diversity in the genus Psidium. The present study aims to cryopreserve the pollen of Psidium species to overcome asynchronous flowering. The pollen of different Psidium species were germinated in vitro in an optimized medium of germination. In vitro/in vivo pollen viability assessment and SEM analysis were carried out to determine the changes after cryopreservation. The in vitro pollen viability was determined at monthly intervals starting from fresh pollen until six months of cryopreservation. The in vivo fertility tests were carried out by pollination using both fresh and cryopreserved pollen. The cryopreserved pollen showed in vitro germination ranging from 1.78% (in P. molle) to 81.67% (in "H 12-5") compared to fresh pollen (2.16% in P. molle to 86.08% in P. guineense). In vivo fertility was tested by controlled pollination using six-month-old cryopreserved pollen and it resulted in fruit setting ranged between 3.33% (P. cattleianum var. cattleianum) and 27.66% (P. chinensis) as compared to fresh pollen between 4.0% (P. cattleianum var. cattleianum) and 30.66% (P. chinensis). Seed set and germination was also recorded in all the crosses attempted using cryopreserved pollen. These in vitro and in vivo results indicated that cryopreservation is an effective technique for breeding and conserving the haploid gene pool in cryo genebank. Scanning Electron Microscopic studies of pollen revealed no significant variation in shape and size after cryopreservation when compared to fresh pollen.