IMBIBICIÓN, VIABILIDAD Y VIGOR DE SEMILLAS DE CUATRO ESPECIES DE Opuntia CON GRADO DISTINTO DE DOMESTICACIÓN.

Seed germination is influenced by imbibition capacity, viability and seed vigor; these characteristics could help to explain the few successful germination rate of the genus Opuntia. The aim of this study was to evaluate the imbibition, viability, and vigor of the seeds of nine variants of O. streptacantha, O. hyptiacantha, O. megacantha and O. ficus-indica and its relation to seed biomass and time of collect. The hypothesis was that the imbibition, viability, and vigor of the Opuntia seeds are low and independent of the species and time of harvest. Imbibition was quantified as moisture gain over the original seeds weight. Viability and vigor of the embryos were determined by the tetrazolium test. The experimental design was completely random, with nine treatments (or accessions) and a variable number of repetitions. The results were analyzed with ANOVA, means comparison with the Tukey (p≤0.05) and Pearson correlation tests. The nine variants showed accelerated seed imbibition during the first 8 h. The maximum mean imbibition remained constant at 29 %, for 50-68 h, except for one O. megacantha variant and one O. ficus-indica, both from the Estado de México, which imbibed 60 %. The maximum imbibition was not directly related (p>0.05) with seed biomass of the wild species O. streptacantha; in contrast, in the nearly wild O. hyptiacantha, the fairly domesticated O. megacantha, and the highly domesticated O. ficus-indica, there was a positive and significant correlation (r=0.731 to 0.947). On average, the four species showed 97.6 % seed viability and 94 % vigor, with no significant (p≤0.05) differences. The seeds of the four species reach maximum imbibition within hours, its viability and vigor are significantly high and independent of the species and harvest time. The imbibition ability of the Opuntia seeds is modified by the domestication process. [ABSTRACT FROM AUTHOR]