F. L. Haynes

The heritability of resistance to early blight in diploid potatoes (Solanum tuberosum subsp. phureja and stenotonum)

The heritability of resistance to early blight caused byAlternaria solani (Ell. & Martin) Son was estimated for field grown, diploid potatoes at Fletcher, North Carolina in 1981. Fourteen breeding lines, selected from a random mated hybrid population ofSolanum tuberosum, subsp.phureja andstenotomum, were used. Resistance was measured as the slope obtained by regressing the logit of the disease proportion Y, measured as % defoliation, on time. A wide range of resistance was found. Narrow-sense heritability, as determined by offspring-midparent regression, on an individual plant basis, was calculated to be 0.825.

PHOTOPERIOD EFFECTS ON 2N POLLEN PRODUCTION, RESPONSE TO ANTHER CULTURE, AND NET PHOTOSYNTHESIS OF A DIPLANDROUS CLONE OF SOLANUM PHUREJA

Flow-cytometric analysis of pollen samples obtained fromSolanum phureja, clone PP5, grown under 10, 14, and 18 hour photoperiods at the Southeastern Plant Environment Laboratories of North Carolina State University yielded two populations of pollen based on size parameters. These populations corresponded to pollen separation based on propidium iodide staining of DNA. Anther culture response from plants grown under 14 and 18 hour photoperiods for 8, 10, 12, and 14 weeks was greatest from 8 week old plants grown under a 14 hour photoperiod. Net photosynthesis was significantly higher for plants grown under a 10 hour photoperiod than for plants grown under either a 14, or 18 hour photoperiod. A significant positive correlation was found between net photosynthesis and tuber yield. Results suggest that vegetative growth is increased under short photoperiods, floral development is favored under long photoperiods, and androgenesis is greatest from young plants grown under an intermediate photoperiod.CompendioEn el análisis del flujo citométrico de muestras de polen obtenidas deSolanum phureja, clon PP5, que se mantenía bajo fotoperiodos de 10, 14 y 18 horas, en los Laboratorios para el Ambiente Vegetal del Sureste, de la Universidad Estatal de Carolina del Norte, se obtuvieron dos poblaciones de polen de acuerdo a parámetros relativos al tamaño. Estas poblaciones correspondieron a una separación de polen basada en la tinción del DNA con yoduro de propidium. La respuesta de los cultivos de anteras de plantas que crecían bajo fotoperíodos de 14 y 18 horas por 8, 10, 12, y 14 semanas fue mucho mayor que la de cultivos provenientes de plantas de 8 semanas creciendo bajo un fotoperiodos de 14 horas. La fotosíntesis neta fue significativamente más alta para plantas creciendo bajo un fotoperíodos de 10 horas que para plantas creciendo bajo fotoperíodos de 14 o 18 horas. Se encontró una correlatión positiva significativa entre la fotosíntesis neta y el rendimiento en tubérculos. Los resultados sugieren que el crecimiento vegetativo es incrementado bajo fotoperíodos cortos, el desarrollo de las flores es favorecido bajo fotoperíodos largos, y la androgenesis es mucho mayor en plantas jóvenes creciendo bajo un fotoperíodo moderado.

Stability of high specific gravity genotypes of potatoes under high temperatures

An initial population of PHU-STN hybrid diploid potatoes was screened in 1978 at the Mountain Horticultural Crops Research Station, Fletcher, N.C. for high specific gravity and tuber production. Sixty clones were selected for testing under high temperatures at two North Carolina coastal locations. Twenty-seven clones maintained a relatively high specific gravity and acceptable tuber production under these high temperatures. The other 33 either were low in specific gravity or produced few, if any, tubers. Specific gravity was lower at the two coastal locations than at the Mountain Horticultural Crops Research Station.The 27 relatively stable, high specific gravity clones were retested in 1980 along with seven additional clones included for the first time. Severe high temperatures resulted in low survival rates and low specific gravity. However, eight clones maintained a relatively high specific gravity in relation to the rest of the population.ResumenUna población inicial compuesta por híbridos diploides de Phureja-Stenotonum, fue tamizada en 1978 en la Estación Experimental de la Montaña, de Cultivos Horticulturales de Fletcher, Carolina del Norte; para obtener alto contenido de peso específico y producción de tubérculos. Sesenta clones se seleccionaron bajo condiciones de temperatura alta en dos localidades costaneras de Carolina del Norte. Veintisiete de ellos mantuvieron relativamente un alto peso específico y una producción de tubérculos aceptable bajo dichas condiciones. Los 33 clones restantes tuvieron bajo peso específico o escasa o ninguna producción. El peso específico fue más bajo en las dos localidades costaneras que en la Estación Experimental de la Montaña.Veintisiete clones, relativamente estables en peso específico, fueron evaluados una vez más en 1980, junto con siete clones adicionales incluídos por primera vez. La incidencia de temperaturas altas muy severas, dieron lugar a proporciones bajas de sobrevivencia y a bajo peso específico, sin embargo, ocho clones mantuvieron relativamente un alto peso específico en relatión al resto de la población.

Recurrent selection for heat tolerance in diploid potatoes (solanum tuberosum subsp.phureja andstenotomum)

The response of diploid potatoes to growing seasons of high temperatures was studied at two locations in eastern North Carolina. The responses measured were survival, tuberization, and yield. One cycle of phenotypic recurrent selection for yield resulted in increases of 3% for survival, 15% for tuberization, and 27% for yield. Heritability of yield, estimated from selection response, was 0.07 for the combined locations. There was a small positive phenotypic correlation between the responses.ResumenLa repuesta de papa diploide a temporadas de cultivo con temperaturas altas fue estudiada en dos localidades en el oriente de Carolina del Norte. Las repuestas medidas fueron las de sobrevivencia, tuberización y rendimiento. Un ciclo de selección fenotipica récurrente para el rendimiento resultó en aumentos del orden de 3% en sobrevivencia, 15% en tuberización y 27% en rendimiento. La heredabilidad para rendimiento, estimada por la respuesta de las selecciones, fue 0,07 para la combinatión de ambas localidades. Hubo una pequeña correlatión fenotípica positiva entre las respuestas.

Potato embryo culture

SummaryImmature embryos of the potato were culturedin vitro, and grown to seedlings of a size that could be transplanted to soil in pots. Embryos excised and transplanted to culture medium seventeen days after pollination were grown successfully.Embryos may be cultured as early as fourteen days after pollination provided whole ovules are transplanted to the culture medium, and if the embryos are excised from the ovules and re-transplanted about ten days later.

Variability of flowering and 2n pollen production in diploid potatoes under high temperatures

Nine clones from a heat tolerant PHU-STN hybrid population were evaluated for flower production and percent normal, 2n and non-viable pollen under three temperature regimes at the Southeastern Plant Environmental Laboratories: 30/26, 26/22 and 22/18 C. No flowering was observed at 30/26 C. Flowering was irregular among seven of the clones at 26/22 C and 22/18 C. One clone produced numerous flowers at 26/22 C and 22/18 C. The plot of percent 2n pollen against time for this one clone under 22/18 C revealed a slope which was statistically different from zero but too small to be of practical value. The same plot of this clone under 26/22 C revealed a slope which was not statistically different from zero. Percent 2n pollen was statistically greater (at the 10% level of significance) in the 26/22 C chamber than the 22/18 C chamber.ResumenSe evaluaron nueve clones de una población híbrida PHU-STN tolerante al calor para producción de flores y porciento de polen normal, 2n y no-viable, bajo tres regímenes de temperatura (30/26, 26/22 y 22/18°C), en los Laboratorios de Ambiente Vegetal del Sureste. No se observó floración a 30/26°C. La floración fué irregular, en siete de los clones, a 26/22°C y a 22/18°C. Un clon produjo numerosas flores a 26/22°C y a 22/18°C. El gráfico del porcentaje de polen 2n, en relación al tiempo, para este clon, bajo 22/18°C, reveló una pendiente que era estadísticamente diferente a cero, pero demasiado pequena para ser de valor práctico. La misma comparación, pero bajo 26/22°C, mostró una pendiente que no era estadísticamente diferente a cero. El porciento de polen 2n fue estadísticamente mayor (al nivel del 10%) en la cámara a 26/22°C que en la de 22/18°C.

The effect of wet soil and carbon dioxide on potato chip color and sugar content

A large portion of tim early potato crop produced in the southern states is lnade into potato chips. At harvest the early white-skinned varieties such as Sebago, Cobbler, Katahdin and Plymouth usually produce a desirable light golden brown chip and, with lnoderately warm storage conditions, continue to do so (6). Sometimes potatoes producing lightcolored chips at harvest will produce dark undesirable chips after being held a few days. The variations in chip color at harvest as well as the differences in response of tubers after comparable holding conditions are serious problems for the chip nmnufacturers. Previous work (8) indicated that soil moisture affected chipping quality of potatoes. \Vet soil reduces aeration, and causes an acculnulation of carbon dioxide and a reduction of oxygen in the soil. Previous work has shown that carbon dioxide increases in tubers stored under moist conditions (10) and in those stored at atlnospheres high in carbon dioxide (3, 4). Total sugar content increased in tubers subjected to above normnal levels of carbon dioxide in storage, although very little change occurred in reducing sugars (1, 5, 11). Miyamoto et al (9) reported that tubers subjected to either wet air or 10 per cent carbon dioxide produced dark colored chips. These studies were undertaken to deterlnine the relation of soil mnoisture to the carbon dioxide and oxygen content of potatoes and to their quality for chip manufacture; additionally to determine whether high levels of carbon dioxide in storage produce ch[p color changes observed in potatoes with high carbon dioxide content caused by field conditions.

The effect of day and night temperatures on bud initiation and flowering in diploid potatoes

Eight clones from a diploid hybrid population ofSolanum tuberosum subsp.phureja andstenotomum were grown at the Southeastern Plant Environmental Laboratories under simulated long day conditions under six day/night temperature regimes: 22/18, 22/14, 22/10, 26/18, 26/14 and 26/10 C.Time to bud initiation was not significantly affected by daytime temperature (22 vs 26 C). However, decreasing night temperature significantly increased the time to bud initiation.At 10 C night temperatures bud abortion was 100%, bud initiation failed to occur, or the initiated buds failed to flower before the end of the experiment for all clones except one. Bud abortion and flowering were not significantly affected by temperature regime in the remaining four chambers (26/18, 26/14, 22/18 and 22/14 C). However, there were highly significant differences in bud abortion and flowering among clones at the different temperature regimes.CompendioSe sembraron ocho clones de una población de híbridos diploides de Solanum tuberosum subsp. phureja y stenotomum en Southeastern Plant Environmental Laboratories, bajo condiciones simuladas de día largo y seis regímenes de temperatura diurna/nocturna de: 22/18, 22/14, 22/10, 26/18, 26/14, y 26/10°C.El momenta de la iniciación de la yema no fué afectado significativamente por temperaturas diurnas (22 vs 26°C). Sin embargo, disminuyendo la temperatura nocturna aumentó significativamente el tiempo de iniciación de la yema.

Boone — A new variety of potato resistant to late blight and adapted to western north carolina

SummaryBoone (U.S.D.A. B 880-4) is a late-maturing, high-yielding variety. The tubers are medium oblong, very smooth and shallow-eyed. They do not sprout in storage until late in the spring. Boone is highly resistant to, if not immune from, the common race of the late blight fungus.

Coastal Chip: A chipping potato variety resistant to heat stress

Coastal Chip is a medium-late maturing potato chipping variety suitable for production in locations along the east coast of the United States where heat stress reduces internal quality of tubers. It yields as well as the variety Atlantic but is not as susceptible to heat necrosis. The specific gravity of Coastal Chip averages approximately 0.010 less than Atlantic at locations subject to heat stress. In the seed producing areas of Maine it’s specific gravity averages approximately 0.005 less than that of Atlantic. Tubers are round, netted-skinned, and have moderately deep stem and bud ends. Chips from Coastal Chip are slightly lighter in color than those produced by Atlantic. In mid-Atlantic states where heat stress adversely affects chip color Coastal Chip processes into chips for a slightly longer period of time after harvest than does Atlantic. Glycoalkaloid content of Coastal Chip averaged 7.9 mg/100 g fresh tissue. Sunburned (green) tubers of Coastal Chip develop purple streaks that remain following processing. Hills must be properly covered to reduce losses. Coastal Chip is resistant to race A of the golden nematode (Globodera rostochiensis) and potato virus A. It is tolerant to Verticillium wilt, more susceptible to common scab and Rhizoctonia than Atlantic and susceptible to potato virus X.CompendioCoastal Chip es una variedad de papa de maduracion semitardía, de buena calidad para fritura a la inglesa, apropiada para ser producida en lugares de la costa oriental de los Estados Unidos donde el estrés por calor reduce la calidad interna de los tubérculos. Rinde tanto como la variedad Atlantic, pero no es susceptible a la necrosis por calor. La gravedad específica de Coastal Chip promedia aproximadamente 0,010 menos que la de Atlantic en los lugares expuestos al estrés por calor. En las zonas productoras de semilla en Maine su gravedad específica promedia aproximadamente 0,005 menos que la de Atlantic. Sus tubérculos son redondos, con piel reticulada y tienen extremos basales y apicales moderadamente deprimidos. Las papas fritas de Coastal Chip son de color ligeramente más claro que aquellas producidas con Atlantic. En los estados centrales del Atlántico donde el estrés por calor afecta severamente el color de las papas fritas a la inglesa, el procesamiento de Coastal Chip, después de la cosecha, toma un tiempo ligeramente mayor de aquel registrado para Atlantic. El contenido de glicoalcaloides de Coastal Chip promedia 7,9 mg/100 g de tejido fresco. El verdeo de los tubérculos de Coastal Chip expuestos al sol desarrolla estrías de color purpura que permanecen aún después del procesamiento. Los montículos de papa deben ser cubiertos adecuadamente para reducir las pérdidas. Coastal Chip es resistente a la raza A del nematodo dorado (Gbbodera rostochiensis) y al virus A de la papa. Es tolerante a la marchitez porVerticillium, más susceptible a la sarna común y aRhizoctonia que Atlantic y susceptible al virus X de la papa.