The castor bean (Ricinus communis L.) has great importance for the economy of the semi-arid region of the northeast of Brazil, responsible for 80% of the national production, but during 1970 and 2000, the net production of this oil crop was reduced. Existence of some 90 different types of seeds used in the cultivation of this Euforbiaceae was also verified. Due to this problem, the Processing and Storage of Agricultural Products Laboratory of DEAg/UFCG, has tried to develop cryoconservation technique for two varieties of Ricinus communis, in order to obtain a secured storage for an indefinite time. The experimental delineation was a completely randomized, with the data obtained on the 7th and 14th day after sowing, in a factorial scheme 2 x 3 x 2 x 2 (2 varieties x 3 cryoconservation periods x 2 cryoconservation temperatures x 2 types of conditioning) with eight repetitions of twenty-five seeds each. The data obtained were submitted to an variance analysis and the means were compared by the Tukey's, test at 5% of probability. From the results obtained it can be concluded that: the maximum level of humidity for the cryoconservation of the seeds of the two varieties of Ricinus communis (nordestina and pernambucana) is between 4 and 10% on wet basis; the best results of physiological quality were obtained after 30 days of cryoconservation and may either be cryoconserved in the vapor (-176 ºC) or by immersion (-196 ºC) in liquid nitrogen; for storage of seeds, canister of aluminum proved to be better than that of PVC.
maximum level of humidity; Ricinus commumis L.; liquid nitrogen
