Russet Burbank' has limited fertility and has not parented improved cultivars through traditional breeding efforts. This study showed that 'Russet Burbank' (NB clone) could be improved through selection of intraclones (somatic embryos derived from specific tuber tissues) based on field performance and/or processing characteristics. In 2005 and 2006, approx. 800 intraclones were regenerated from field-grown tubers or microtubers. Intraclones were micropropagated, acclimatized, and field-tested to identify the highest yielding lines. Each season, following storage, tubers of selected lines were tested for glucose content and French fry-processing quality. In 2007, the best intraclones from earlier seasons were increased through micropropagation and retested for yield and processing features. Approx. 2-9% of intraclones had similar yield to controls but superior processing features. Neither tuber source nor explant tissue type affected intraclone tuber yield, type, or processing characters. We recommend the incorporation of somatic embryogenesis into potato improvement programs for processing quality traits.Resumen "Russet Burbank" tiene fertilidad limitada y no ha sido progenitor que haya mejorado variedades a través de esfuerzos de mejoramiento tradicional. Este estudio demostró que "Ruset Burbank" (clon NB) pudo mejorarse por selección de intraclones (embriones somáticos derivados de tejidos específicos de tubérculo) con base en el comportamiento en el campo y/o en características de procesamiento. En 2005 y 2006, se regeneraron aproximadamente 800 intraclones de tubérculos cultivados en el campo o de microtubérculos. Los intraclones se micropropagaron, se aclimataron, y se probaron en el campo para identificar las líneas de rendimiento más alto. En cada ciclo de cultivo, después del almacenamiento, se probaron tubérculos de líneas selectas para el contenido de glucosa y de calidad de fritura para papas a la francesa. En 2007, los mejores intraclones de siembras previas se incrementaron por micropropagación y se volvieron a probar para rendimiento y características de procesamiento. Aproximadamente el 2-9% de intraclones tuvieron rendimiento similar al de los testigos pero mejores características de procesamiento. Ni la fuente del tubér-culo ni el tipo de tejido del explante (inóculo) afectaron el rendimiento de tubérculo de los intraclones, o el tipo o características del procesamiento. Recomendamos la incorporación de embriogénesis somática en los programas de mejoramiento de papa para las características de calidad en el procesamiento.

SummaryBoron (B) requirements differ widely among plant species and the concentration range between toxicity and deficiency is less for B than for any other nutrient. Excess B can adversely affect calcium (Ca) uptake and plant growth. Potato cvs Bintje and Norland plantlets were micropropagated on Murashige & Skoog (MS) nutrient medium, supplemented with 3 (MS control level) or 9 mM Ca, and a range of HsBO3 levels (0.025 to 0.300 mM B). Medium B levels of 0.100 and 0.300 mM decreased Ca cotitentin leaves and shoots of cv. Norlafid, but not Bintje. Medium B level of 0.025 mM, which is 25 % of the control MS level, enhanced Ca uptake in cv. Norland and did not compromise normal plantlet growth in either cultivar. This lower H~B03 level (0.025 mM B), and a B-free gelling agent such as Gelrite, could be used for mlcropropagation of potato and possibly other species susceptible to Ca deficiency disorders.

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Ca uptake by micropropagated ‘Norland’ potato plantlets was investigated in relation to cation and macroelement salt concentrations in modified Murashige and Skoog (1962) basal media. Increased Ca:specific cations, by lowering NH4, Mg, or K, had little effect on the Ca content of plantlets grown on these media. Increased Ca:total cation ratio, by raising Ca from 3 to 6 mM in the medium, promoted Ca content of micropropagated plantlets. At equivalent Ca:total cation ratio, macroelement dilution increased the osmotic potential of the medium, and had an even greater impact on plantlet shoot Ca content. Root pressure, which is sensitive to variations in salt concentration, was probably the primary Ca delivery method to developing tissues since transpiration was limited in vitro. In vitro systems appear ideal for studying some aspects of nutrient relationships of plants.