G. R. Johnston

Glycoalkaloid content of B5141-6 potatoes.

A cross-Canada survey of B5141-63 potatoes grown at 12 locations showed a distinct bitter off-flavour found to be due to the presence of unusually high total glycoalkaloid content (TGA), mostly in excess of 20 mg per 100 gm of fresh weight. Samples of check varieties commonly grown in the selected locations, Kennebec, Irish Cobbler and Netted Gem, showed comparably low, normal TGA levels.As there is strong evidence that the high TGA levels in B5141-6 tubers are reached before detachment from the mother plant, it is assumed that the ability of B5141-6 to produce or accumulate such high levels is strongly inherited. To date, high TGA levels were found to be only due to the effects of post-harvest environment (6, 7). The implications of the TGA potential are discussed in relation to the existing potato improvement programmes and the need for a routine screening test for new introductions.ResumenEn un estudio en el Canadá, papas B5141-6 cultivadas en 12 localidades mostraron un marcado amargor debido a la presencia de alto contenido de glicoalcaloide (TGA), generalmente con un exceso de 20 mg por 100 g de peso fresco. Muestras de variedades testigos comunmente cultivadas en las localidades seleccionadas, Kennebec, Irish Cobbler y Netted Gem, mostraron comparativamente bajos (normal) niveles de TGA.Como hay bastante evidencia de que los altos niveles de TGA en tubérculos B5141-6 son alcanzados antes de su separación de la planta madre, se sospecha que la habilidad de B5141-6 para producir o acumular alto nivel de TGA es heredada. Hasta la fecha, se ha encontrado que los altos niveles de TGA se deben sólamente a los efectos del ambiente después de la cosecha. Las implicaciones del potencial de TGA se discuten en relación con los programas de mejoramiento existentes y la necesidad de una prueba para la selección rutinaria de la nuevas introducciones.

Yield potential and genotype-environment interactions of tetraploid-diploid (4x-2x) potato hybrids

Six advanced selections of a population of 4x-2x hybrids were tested and compared with six well-adapted Group Tuberosum cultivars under field conditions at four locations in Canada over two years.Three 4x-2x hybrids produced a total and a marketable yield which was equal to or higher than that of most cultivars over eight environments. For marketable yield considerable differences existed between genotypes in the amount of variation occurring over the eight environments. Both groups of genotypes contained clones with low and high variation for marketable yield.Analysis of genotype-environment (GE) interactions for marketable yield indicated that all genotypes differed from each other in their responses to the environmental effects. However, there was no clear distinction between the group of 4x-2x hybrids and the group of cultivars for the GE interaction patterns. It appears that the heterosis of the 4x-2x hybrids is the result of a broadening of the genetic base of Group Tuberosum breeding stocks by the incorporation of germ plasm from the primitive diploid South American cultivars. Development of improved diploid parents is necessary in order to achieve the full potential of the 4x-2x hybridization method.ResumenSeis selecciones avanzadas de una población de híbridos 4x - 2x se evaluaron y compararon con seis cultivares del Gp. Tuberosum adaptados bajo condiciones de campo durante dos años en cuatro localidades de Canadá.Tres hibridos 4x - 2x dieron rendimientos totales y comerciales iguales o mayores que la mayoría de los cultivares sobre los ochos ambientes. Se encontraron diferencias genotípicas marcadas para el rendimiento comercial con respecto a la variación ambiental. Ambos grupos de genotipos tuvieron clones con alta y baja variación con respecto a su rendimiento comercial.El análisis sobre interacción genotipo-ambiente (GE) para el rendimiento comercial indicó que todos los genotipos tienen respuesta diferencial a los efectos ambientales. Sin embargo, no hubo clara distinción entre los híbridos del grupo 4x -2x el grupo de cultivares con respecto a su interacción con el ambiente (GE). Es de esperar que la heterosis de los híbridos 4x -2x sea el resultado de la amplicación de la base genética del Grupo Tuberosum debido a la incorporación de germoplasma proveniente de cultivares primitivos diploides de Sudamérica. Es necesario el mejoramiento de los progenitores diploides para alcanzar el máximo potencial del método de hibridación 4x - 2x.

Reliability of potato selection in the first clonal generation

Studies were carried out over a seven-year period to determine the reliability of selection at the single hill stage; two clonal replicates of 200 unselected first clonal generation seedlings, and 10 established cultivars were used as test materials.Duplicate selections of clones were made in relatively few instances; consequently, the reliability of selection at the single hill stage is highly questionable. Several modifications in procedure are proposed including the application of negative selection pressure, using replication where possible, discarding only the obviously poor clones, and modifying the criteria used as a basis for selection and limiting the number of hills per clone grown the second year.

Yukon Gold: A new yellow-fleshed, medium-early, high quality table and French-fry cultivar

Yukon Gold is a medium-early, yellow-fleshed potato cultivar with very good boiling, baking, and French-frying quality. It is not suitable for chips. In Ontario its yield is similar to Russet Burbank’s. Plants are susceptible to virus Y and slightly susceptible to virus leafroll but are resistant to mild mosaic. Tubers are moderately susceptible to common scab,Streptomyces scabies.ResumenYukon Gold es una variedad temprana a intermedia, de carne amarilla con muy buenas cualidades para coción, horneado y papas fritas. No es adecuada para “chips”. Su rendimiento es similar a “Russet Burbank” en Ontario. Es susceptible a virus Y y ligeramente susceptible al virus del enrrollamiento pero resistente a mosaico moderado. Los tubérculos son de susceptibilidad moderada a la sarna común,Streptomyces scabies.

Rose Gold: A yellow fleshed, pink-red skinned, tablestock cultivar with short dormancy and full season maturity

Rose Gold is a pink-red skinned, bright yellow fleshed, tablestock potato cultivar. In Ontario trials, Rose Gold is later maturing than its half sibling Red Gold and is characterized by producing larger and fewer tubers per plant than Red Gold. Rose Gold rarely develops symptoms of virus diseases when grown for repeated generations under high virus disease pressure (PVY, PLRV, PVX). Tubers have a very short dormancy. Yields are similar to Yukon Gold on mineral soil and generally higher than Red Gold. Rose Gold has produced high marketable yields on muck soil.CompendioRose Gold es un cultivar de papa para consumo de piel rosado-rojiza y carne de color amarillo intenso. En ensayos llevados a cabo en Ontario, Rose Gold madura más tardíamente que su medio hermana Red Gold y se caracteriza por producir por planta un menor número de tubérculos de mayor tamaño que la misma.Rose Gold rara vez desarrolla sintomas de enfermededes viróticas cuando se le utiliza por repetidas generaciones bajo una presión alta de dichas enfermedades (PVY, PLRV, PVX). Los tubérculos tienen un período de reposo muy corto. Los rendimientos son similares a los de Yukon Gold en suelo mineral y generalmente son más altos que los de Red Gold. Rose Gold ha producido altos rendimientos comerciables en suelo Muck.

Effects of seed maturity, size and spacing on the yield of potatoes in Ontario

SummarySeveral years experiments have shown that, under Southern Ontario conditions the following results may be expected.1)Good-quality “A” size seed cut into 11/2 to 2 oz pieces produces total and marketable yields equal to those from whole “B” size seed.2)In 36-inch rows, seed spacing at 12 to 15 inches is best for the Netted Gem (Russet Burbank) variety if there is a perfect plant stand; spacing at 10 inches is satisfactory for Kennebec and Sebago.3)There is no advantage in planting immature seed potatoes and it is uneconomic to produce them because of losses during storage and the low yield obtained from early harvesting.4)The present maximum of 12 oz for “A” size seed is too large for economical use of seed.ResumenVarios años de experimentación indican que bajo las condiciones del sur de Ontario pueden esperarse los resultados siguientes.1)Semilla de buena calidad del tamaño “A” cortada en pedazos de 11/2 a 2 onzas da una producción total y comerciable igual a la obtenida con la semilla entera del tamaño “B.”2)En hileras están aparte 36 pulgadas, el mejor espaciado de planats para la variedad Netted Gem (Russet Burbank) era de 12 a 15 pulgadas, si todas los espacios estaban llenos. El espaciado de 10 pulgadas fué satisfactorio para Kennebec y Sebago.3)No hay ventaja en sembrar semilla de papa inmatura ni es económico producirla a causa de las pérdidas durante el almacenaje y el bajo rendimiento obtenido de una cosecha temprana.4)El tamaño máximo actual de 12 onzas para la semilla del tamaño “A” es demasiado grande para un uso económico de la semilla.

Red Gold: A yellow-fleshed, red-skinned potato cultivar with short dormancy and high tuber set

Red Gold is a midseason maturity potato with pink-red skin and a bright yellow flesh. It is characterized by having a high set per plant of medium-small sized tubers. Marketable yields in Ontario, Canada are similar to or slightly less than Conestoga, Yukon Gold, and Superior. Boiling, baking, and field chip quality are acceptable with medium specific gravities (1.070–1.080). Short tuber dormancy makes this variety well adapted for whole seed tuber production for fall export markets. Red Gold has performed well in trials in Uruguay. Red Gold is moderately resistant to scab, field resistant to virus Y and leafroll, and susceptible to mild mosaic.CompendioRed Gold es una papa de madurez a media temporada con piel rojorosada y carne amarilla brillante. Se caracteriza por tener una gran formación de tubérculos de tamaño medio a pequeño, por planta. Los rendimientos comerciables en Ontario, Canada, son similares o ligeramente menores a los de Conestoga, Yukon Gold, y Superior. La calidad a la cocción, horneado y fritura es aceptable, con gravedades de término medio (1,070–1,080). El corto período de reposos de los tubérculos hace que esta variedad se adapte bien para la producción con tubérculos-semillas enteros, para los mercados de exportación en otoño. La performance de Red Gold ha sido buena en los ensayos de producción para mercados de exportación en otoño. Red Gold se ha comportado bien en ensayos en el Uruguay. Red Gold es moderadamente resistente a la sarna común, tiene resistencia de campo at PVY y al PLRV, y es susceptible al mosaico leve de la papa.

The longevity of seeds of the common potato,Solanum tuberosum

One hundred true seeds of 101 genetically distinct varieties ofSolanum tuberosum which had been collected during the harvest years 1958–1978 were allowed to germinate on moist filter paper in sealed petri dishes stored at 12°C and provided with a 7 hour day. Little vigor is lost in seeds 10 years old and no varietal differences were evident. Germination in all populations commenced on the 5th or 6th day and was completed five days later. Seeds older than 10 years began germination more slowly and the populations took longer to achieve maximum germination. Varietal differences became evident in older seeds. True seed ofS. tuberosum can be stored without stringent conditions with the expectation of good germination for 15 years and some germination for 20 years.ResumenCien semillas botánicas de 101 variedades genéticamente distintas deSolanum tuberosum que habian sido coleccionadas durante los años 1958–1978 fueron germinadas en papel filtro húmedo en discos petri sellados, almacenadas a 12°C bajo siete horas de luz. Muy poco vigor se pierde en semillas de 10 años de edad y las diferencias varietales no fueron evidentes. La germinación en todas las poblaciones comenzó al 5° 6 6° día y fue completada cinco días después. Semillas de más de 10 años empezaron a germinar más lentamente y a las poblaciones les tomó más tiempo para alcanzar la germinación màxima. En las semillas más viejas las diferencias varietales se hicieron evidentes. La semilla botánica deS. tuberosum puede ser almacenada sin mayores condiciones especiales con una expectativa de buena germinación por 15 aflos y menor germinación por 20 años.

Determination of tuber sizing and accumulation of total solids contents of four potato varieties harvested at several dates

SummaryA determination of the tuber sizing and the accumulation of total solids content during the growing season of potato varieties is considered an important phase of the Ontario Regional Trials. Data on the above are reported for four varieties over a four-year period 1957–60. In all years, the total solids contents of the “early” varieties reached a maximum by mid-August. The maximum number and yield of Ontario No. 1 size tubers of these was also attained during this period or shortly after. In three out of four years the “late” varieties also reached a maximum solids content by mid-August, but the number and yield of Ontario No. 1 size tubers of the “lates” usually continued to increase into September. In the Guelph region of Ontario the period of greatest yield gains was from mid-July to mid-August for the earlies and from early August to early September for the lates. Following the peak period of total solids content, generally occurring in mid-August, a levelling off (sometimes a decline) in the solids content was most frequently noted. It is suggested that Ontario potatoes which are to be stored may be harvested earlier with little reduction in yield and no reduction in total solids. This is particularly important when the potatoes are to be processed.

Alternative sources of nitrogen and phosphorus in potato fertilizer

Urea and diammonium phosphate were compared with ammonium nitrate and triple superphosphate, in all combinations, as sources of N and P in fertilizer on two soil types important in potato production in Ontario. Greenhouse experiments with these soils and a peat:vermiculite:sand mixture gave very varied root and shoot development which followed no constant pattern. The same combinations of fertilizer in the field gave no differences in emergence, appearance, or senescence, but there was one yield difference and minor, inconsistent differences in specific gravity and cooking quality.ResumenUrea y fosfato diamónica fueron comparados con nitrato de amonio y superfosfato triple, en todas las combinaciones como fuente de N y P en dos tipos de suelo importantes en la productión de papa en Ontario. Experimentos de invernadero con esos suelos y una mexcla de musgo, vermiculita y arena dieron desarrollos variables de raíz y ápice no siguiendo un modelo constante. Las mismas combinaciones de fertilizante en el campo no dieron diferencias en emergencia, apariencia o senescencia pero hubo una diferencia en rendimiento y diferencias menores y no consistentes en gravedad especifica y calidad culinaria.