Variability within Opuntia ficus-indica Mill. cv. "Yellow fruit without spines" in Santiago del Estero, Argentina and individual plant selection for improved yield and fruit characteristics

As observed in farmers plantations near Santiago del Estero, Argentina, Opuntia ficus-indica var. 'Santiague (n) over tildeo' has low coefficients of variation for brix (5.9%), pH (1.4%), height (9.7%) and total number of cladodes (21%) but it has very high variability for all characters associated with yield i.e. cladodes with fruit (51%) and total fruit per plant (71%). In contrast an accession known to be propagated from the same plant had a coefficient of variation of only 6% for fruit production. This suggests that the "Santiagueno variety" may be a mixture of clones with the same fruit characteristics i.e. fruit color, pH and brix but different yield characteristics. We suggest that it is necessary to examine the variability in other varieties that have not resulted from formal research programs, and to begin a world wide sub-varietal characterization of unique clones that may only be distinguished by quantitative agronomic characters such as yield, percentage pulp, resistance biotic and abiotic factors. We also report on the identification of 7 "Santiagueno" clones with at least 17 kg of fruit per plant that are being multiplied for future plantations and being evaluated in replicated trials.