Development of probabilistic tools to assist in the establishment and management of cryopreserved plant germplasm collections.

A simple method, based on the binomial distribution, is proposed to calculate the probability of recovering at least one (or any other fixed number of) plant(s) from a cryobank sample using four given parameters: the percentage of plant recovery observed from a control sample, pobs, the number of propagules used for this control, n1, the number of propagules in the cryobank sample, n2, a chosen risk for the calculation of a confidence interval for the observed plant recovery, alpha. Using this method, it is possible to assess the number of propagules which should be rewarmed immediately after freezing in order to estimate the plant recovery percentage as a function of the total number of propagules available. It also allows the calculation of the minimum plant recovery percentage to ensure that the probability to recover at least one (or A, with A>1) plant(s) is higher than a fixed probability level, as a function of the control and the cryobank sample sizes. Reciprocally, once the plant recovery percentage has been estimated, it is possible to assess the minimum size of the cryobank sample to obtain a probability to recover at least one (or A, with A>1) plant(s) higher than some fixed level.