Elisa Salas

Traditional Processing of Black and White Chuño in the Peruvian Andes: Regional Variants and Effect on the Mineral Content of Native Potato Cultivars

Traditional Processing of Black and WhiteChuñoin the Peruvian Andes: Regional Variants and Effect on the Mineral Content of Native Potato Cultivars. Farmers in the high Andes of central to southern Peru and Bolivia typically freeze-dry potatoes to obtain chuño. Processing of so-called black chuño follows tending, treading, freezing, and drying. The making of white chuño is generally more complex and involves exposure of tubers to water. Regional variants exist for each of these processes, yet their influence on the nutritional composition of native potato cultivars is little known. Tubers belonging to four distinct cultivars and produced in a replicated trial under uniform conditions were processed into four types of chuño following standard traditional procedures (farmer-managed). These regional variants were documented, and the dry matter, iron, zinc, calcium, potassium, phosphorus, magnesium, and sodium content of the four resulting different types of boiled chuño determined at the International Potato Center’s Quality and Nutrition Laboratory (Lima, Peru). Content values were compared with those of boiled (unprocessed) tubers from the same experiment. Regional variants of processing are to a large extent determined by tradition, environmental condition, and market demand. The zinc, potassium, phosphorus, and magnesium content of all types of chuño decreases in comparison with unprocessed tubers. Concentrations of these same minerals decrease more drastically for white as compared to black chuño. The effect of the four regional variants of freeze-drying on the dry matter, iron, calcium, and sodium content of chuño differs by process and/or cultivar.Procesamiento tradicional dechuñonegro y blanco en los Andes Peruanos: Variantes regionales y efecto sobre el contenido de minerales en cultivares nativos de papa. Los agricultores de la zona Alto Andina del centro al sur del Perú y Bolivia someten a la papa a un proceso de congelado-secado para obtener chuño. El procesamiento del chuño negro involucra tender, pisar, congelar y secar. Por lo general la elaboración del chuño blanco es más compleja y requiere que los tubérculos se remojen en agua. Existen variantes regionales para cada uno de los procesos. Sin embargo, la influencia de estas sobre la composición nutricional de cultivares nativos es poco conocida. Tubérculos de cuatro cultivares distintos y producidos en un ensayo replicado bajo condiciones uniformes fueron procesados en cuatro ‘tipos’ de chuño siguiendo procedimientos tradicionales estándar (manejo de agricultor). Se documentaron las variantes regionales y se determinó el contenido de materia seca, hierro, zinc, calcio, potasio, fósforo, magnesio y sodio de los cuatro diferentes ‘tipos’ de chuño en el Laboratorio de Calidad y Nutrición del Centro Internacional de la Papa (Lima, Perú). Se compararon los valores de contenido del chuño con los de tubérculos hervidos (sin procesar) provenientes del mismo experimento. Los variantes regionales de procesamiento se determinan principalmente por tradición, condición ambiental y demanda de mercado. El contenido de zinc, potasio, fósforo y magnesio de todos los tipos de chuño disminuyó en comparación con tubérculos sin procesar. Las concentraciones de estos minerales disminuyó más drásticamente para chuño blanco comparado con chuño negro. El efecto de los cuatro variantes de congelado-secado sobre el contenido de materia seca, hierro, calcio y sodio del chuño varió dependiendo del proceso y/o cultivar.

Tuber shape and eye depth variation in a diploid family of Andean potatoes

BackgroundTuber appearance is highly variable in the Andean cultivated potato germplasm. The diploid backcross mapping population ‘DMDD’ derived from the recently sequenced genome ‘DM’ represents a sample of the allelic variation for tuber shape and eye depth present in the Andean landraces. Here we evaluate the utility of morphological descriptors for tuber shape for identification of genetic loci responsible for the shape and eye depth variation.ResultsSubjective morphological descriptors and objective tuber length and width measurements were used for assessment of variation in tuber shape and eye depth. Phenotypic data obtained from three trials and male–female based genetic maps were used for quantitative trait locus (QTL) identification. Seven morphological tuber shapes were identified within the population. A continuous distribution of phenotypes was found using the ratio of tuber length to tuber width and a QTL was identified in the paternal map on chromosome 10. Using toPt-437059, the marker at the peak of this QTL, the seven tuber shapes were classified into two groups: cylindrical and non-cylindrical. In the first group, shapes classified as ‘compressed’, ‘round’, ‘oblong’, and ‘long-oblong’ mainly carried a marker allele originating from the male parent. The tubers in this group had deeper eyes, for which a strong QTL was found at the same location on chromosome 10 of the paternal map. The non-cylindrical tubers classified as ‘obovoid’, ‘elliptic’, and ‘elongated’ were in the second group, mostly lacking the marker allele originating from the male parent. The main QTL for shape and eye depth were located in the same genomic region as the previously mapped dominant genes for round tuber shape and eye depth. A number of candidate genes underlying the significant QTL markers for tuber shape and eye depth were identified.ConclusionsUtilization of a molecular marker at the shape and eye depth QTL enabled the reclassification of the variation in general tuber shape to two main groups. Quantitative measurement of the length and width at different parts of the tuber is recommended to accompany the morphological descriptor classification to correctly capture the shape variation.

Extreme salinity as a challenge to grow potatoes under Mars-like soil conditions: targeting promising genotypes.

One of the future challenges to produce food in a Mars environment will be the optimization of resources through the potential use of the Martian substratum for growing crops as a part of bioregenerative food systems. In vitro plantlets from 65 potato genotypes were rooted in peat-pellets substratum and transplanted in pots filled with Mars-like soil from La Joya desert in Southern Peru. The Mars-like soil was characterized by extreme salinity (an electric conductivity of 19.3 and 52.6 dS m −1 under 1 : 1 and saturation extract of the soil solution, respectively) and plants grown in it were under sub-optimum physiological status indicated by average maximum stomatal conductance 2 O m −2 s −1 even after irrigation. 40% of the genotypes survived and yielded (0.3–5.2 g tuber plant −1 ) where CIP.397099.4, CIP.396311.1 and CIP.390478.9 were targeted as promising materials with 9.3, 8.9 and 5.8% of fresh tuber yield in relation to the control conditions. A combination of appropriate genotypes and soil management will be crucial to withstand extreme salinity, a problem also important in agriculture on Earth that requires more detailed follow-up studies.