Criopreservação de sementes e produção de mudas de Coffea arabica L.

Abstract

For the C. arabica L. species, crops are entirely started from seedling production from seed sowing. Thus, the quality of coffee seeds is of paramount importance, and various factors contribute to the physiological performance of seeds during storage, which is still one of the top technological demands of coffee production. Cryopreservation is a technique that has been widely researched for intermediate and recalcitrant species, and for C. arabica L. seeds, a safe storage protocol has been established with high survival rates after 24 hours of immersion in liquid nitrogen. In this context, four studies were conducted, the first investigating the effects of one year of cryostorage on the physiological quality and isoenzymatic systems of seeds from different cultivars of C. arabica L., aiming to support seedling production at any time of the year. Cryostorage of C. arabica L. seeds for up to one year maintains the physiological quality of the seeds. The activity of catalase, peroxidase, and esterase enzymes in C. arabica L. undergoes changes during cryostorage, but with little association with the physiological performance of seeds. In the second study, seedling production of C. arabica L. was evaluated from seed sowing in all months of the year, in two different environments, nursery and greenhouse, and with three cultivars. The use of cryopreserved seeds allows to produce C. arabica L. seedlings at any time of the year, with the greenhouse providing better seedling performance compared to those produced in the nursery. Sowing of cryopreserved seeds from January to march requires more time for seedling formation, which also shows physiological performance below that of those started from May to July. Seedlings produced with cryopreserved seeds during all months of the year show equal or better performance than those produced with freshly harvested seeds not immersed in liquid nitrogen. In the third study, the physiological aspects of C. arabica L. seedlings produced for nine months of the year in the nursery and greenhouse from seeds stored in liquid nitrogen were evaluated. The levels of chlorophyll a, b, total and stomatal conductance undergo minor modifications related to the sowing time of cryopreserved seeds, regardless of the seedling production location. Sowing of cryopreserved seeds in February and March shows lower physiological performance of seedlings than those sowed in other months studied. In the last study, the survival of C. arabica L. seeds after removal from liquid nitrogen and rewarming was investigated. After cryopreservation, seeds kept under ambient conditions undergo continuous reduction in physiological quality, and germination is maintained within the standards for commercialization for a maximum period of up to two days under ambient conditions. Catalase, esterase, and peroxidase enzymes are indicators of quality for C. arabica L. seeds after cryostorage.