Cryopreservation of Seeds and Embryonic Axes of Several Citrus Species

Abstract

Citrus aurantifolia seeds can be successfully cryopreserved after desiccating them to a moisture content of 12.93% (50% viability) while seeds of C. halimii gave only 25% viability after cryopreservation with a moisture content of 9.5%. Seeds of C. hystrix however, are sensitive to desiccation as they failed to germinate when the moisture content was reduced to 27%, and thus did not survive cryopreservation. The embryonic axes of the three Citrus species gave higher percentage of survival after cryopreservation. 100% survival was obtained with C. aurantifolia and C. halimii embryonic axes with moisture contents of 9–11% and 16.6% respectively. With C. hystrix axes, the highest survival obtained was 60% at a moisture content of 11.04%. Cryopreservation methods i.e. encapsulation—dehydration, slow freezing and vitrification were further employed for the embryonic axes of C. hystrix; however, there was no improvement in the survival percentage obtained.