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Quechua farmers have cultivated mashua (Tropaeolum tuberosum Ruiz & Pavon) and other tuber crops for thousands of years. The practice of trading seed tubers may have contributed to dispersal of viral diseases, such as the tropaeolum mosaic virus (TropMV). We surveyed 17 accessions of mashua collected from Quechua farmers in the provinces of Cuzco and Ayacucho, Peru. Most cross-reacted with the TropMV antibody and showed viral disease symptoms. Significant differences were observed between accessions from Cuzco and Ayacucho, with respect to virus infection and tuber yield under greenhouse conditions. Of the accessions from Cuzco, 87% displayed viral symptoms, while only 22% from Ayacucho showed symptoms. Fewer tubers from Cuzco generated mature plants. In turn, those mature plants produced lower tuber yields. The practice of trading seed tubers may be advantageous for promoting crop diversity but can be harmful when diseased seed tubers are being traded. A program to generate and distribute virus-free seed tubers among Andean farmers would contribute to higher crop yields while preserving local customs and crop diversity.
Asparagus is a vegetable of great economic importance. It is a dioecius and perennial species mainly propagated by seeds, which makes difficult the breeding work as far as results are concerned. New biotechnological techniques such as tissue culture have been used in order to shorten the release of new cultivars. On the order hand, this process depends mainly on the rooting phase, which, for this species, is to some extent difficult. The aim of this work was to verify the influence of spear number on asparagus rooting. Two genotypes were studied: Clone M14 and cv. Deco, which is a hybrid (M14 × G27). These genotypes were tested with one, two, three, and four spears in a medium containing in mg/L: NAA (0.1); kinetin (2.0); ancymidol (0.5). Sucrose was added to 30 g/L and agar at 6.0 g/L. The pH was adjusted to 5.9. The evaluations were performed 30 days later. Four-spear asparagus rooted better than the others; it was also observed longer roots for this treatment. Clone M14 rooted better than cv. Deco. These results show the importance of the starting explants to improve the in vitro rooting in asparagus.