Exploratory studies for cryopreservation of Coffea arabica L. seeds

Abstract

Cryopreservation is a viable option for conservation of coffee germplasm. However, for this technique to be completely successful, it is of fundamental importance to carry out studies that ensure maintenance of cell integrity before and after immersion in liquid nitrogen (LN). Therefore, the aim in this study was to investigate the water content, cooling rate, and final temperature most suitable for cryopreservation of Coffea arabica L. seeds. The seeds were dried by silica gel to water contents of 5, 10, 15, 20, 30 and 40 % wb, subjected to slow cooling treatments at speeds of -1, -3 and -5 °C min.-1 to final temperatures of -40, -50 and -60 °C and then directly immersed in LN. After storage, seeds were rewarmed at 40 °C for two minutes. The survival rate and viability of the seeds and embryos were evaluated by the tetrazolium and germination tests. Results of the tetrazolium test indicate that embryos excised from cryopreserved seeds are less sensitive to cryopreservation than whole seeds are. The water content of 20% wb and the use of zygotic embryos led to the highest survival rate of the coffee seeds, depending on the cooling rate and the final temperature of precooling.