Clinton C. Shock

The effect of timed water stress on quality, total solids and reducing sugar content of potatoes

Potato (Solanum tuberosum L.) solids and reducing sugars were examined before, just after, and two weeks after transient water stress to gain an understanding of tuber changes that occur directly associated with water stress. Russet Burbank and A082260-8 potatoes were grown on Owyhee silt loam at the Malheur Experiment Station, Ontario, Oregon. Potatoes were subjected to a single episode of transient water stress by omitting furrow irrigation in either late June, July, or in early August of 1988 and 1989 to examine variety differences in the short term effects of water stress on changes in solids and reducing sugars in tuber stem ends. Irrigation was managed to maintain soil water potential above -65 kPa at 20 cm depth during tuber initiation through bulking except during transient stress when the soil water potential reached -82 to -110 kPa. Tuber samples were taken from plots and minimally stressed check treatments before stress, at the peak of stress, two weeks after the transient stress period, and after harvest. Tubers were sectioned longitudinally and the percent solids and reducing sugars were determined for samples from the tuber stem end, center, and apical end. Longitudinal tuber strips were fried after harvest to determine fry color. Tuber stem-end fry color did not darken in A082260-8 potatoes subjected to water stress. The line A082260-8 had higher stem-end solids and lower stem-end reducing sugars than Russet Burbank. Neither variety responded to transient water stress or recovery from transient stress with an immediate increase in reducing sugars in any tuber part. Reducing sugars were elevated in harvested tubers, particularly in the stem-ends of Russet Burbank potatoes subjected to water stress. Increases in tuber reducing sugars related to transient water stress were not found during the stress period or immediately after stress, but were present in harvested tubers.CompendioSe examinaron los sólidos y los azúcares reductores de la papa (Solanum tuberosum L.), antes, inmediatamente después y dos semanas después de un breve estrés al agua para determinar los cambios que ocurren en los tubérculos, directamente asociados con el estrés al agua. Papas Russet Burbank y A082260-8 se cultivaron en suelo franco-limoso de Owyhee en la Estación Experimental Malheur, Ontario, Oregón. Las papas fueron expuestas a un solo periodo de breve estrés al agua, omitiendo el riego por surco ya fuese al final de junio, julio o a comienzos de agosto de 1988 y 1989, para determinar las diferencias varietales en los efectos del corto periodo de estrés al agua sobre los sólidos y azúcares reductores en el extremo basal del tubérculo. La irrigación fué suministrada para mantener el potencial de agua del suelo por encima de -65 kPa a 20 cm de profundidad durante el inicio de la tuberización y durante todo el periodo de desarrollo de los tubérculos, excepto durante el breve estrés, en que el potencial de agua del suelo alcanzó de -82 a -100 kPa.Se tomaron de las parcelas, y de los tratamientos testigo con estrés mínimo, muestras de tubérculos antes del estrés, al momento de máximo estrés, dos semanas después del breve periodo de estrés y después de la cosecha.Los tubérculos fueron seccionados longitudinalmente y se determinó el porcentaje de sólidos y de azúcares reductores en muestras tomadas del extremo basal, centro y extremo apical de los mismos. Se frieron rebanadas longitudinales de papas después de la cosecha para determinar el color de la fritura. El color de las porciones basales, después de fritas, no se oscureció en las papas A082260-8 expuestas al estrés al agua. La línea A0822608 tuvo en el extremo basal más sólidos y menos azúcares reductores que Russet Burbank. Ninguna de las variedades respondió al breve estrés al agua o se recobraron del mismo con un aumento inmediato de azúcares reductores en alguna parte del tubérculo. Los azúcares reductores fueron abundantes en los tubérculos cosechados, particularmente en los extremos basales de las papas Russet Burbank expuestas al estrés al agua. Durante el periodo de estrés, o inmediatamente después, no se encontraron incrementos de azúcares reductores en los tubérculos en relation con el breve estrés al agua, pero sí se observaron en los tubérculos cosechados.

Impact of early-season water deficits on Russet Burbank plant development, tuber yield and quality

Russet Burbank potatoes grown on Owyhee silt loam were subjected to early-season moisture stress by delaying initiation of furrow irrigation up to seven weeks after planting. A range of water stress treatments from 4 to 7 weeks after planting resulted in reduced plant size, tuber number and total tuber weight per plant 8 1/2 weeks after planting. Early-season water stress resulting from delayed irrigation onset was associated with improved tuber quality at harvest. Plants water stressed before tuber initiation had fewer tubers with dark stem-end fry colors, reduced percentage of US No. 2 potatoes, and increased percentage and size of US No. 1 potatoes. Increasing duration of soil water potential below -60 kPa early in the season was associated with declining total yield in 1985 but not in 1986. To obtain optimum yield and processing quality, the first irrigation should be no sooner than full plant emergence.CompendioPlantas de papa Russet Burbank que crecían en suelo franco de aluvión de Owyhee fueron sometidas a estrés por humedad al comienzo de la estación, retardando el inicio de la irrigatión por surcos hasta siete semanas después de la siembra. Un rango de tratamientos con estrés por deficiencia de agua de 4 a 7 semanas después de la siembra, causó una reductión en el tamaño de la planta, el número de tubérculos y el peso total de tubérculos por planta a las 8 1/2 semanas después de la siembra. El estrés por deficiencia de agua al comienzo de la estación, résultante del retardo en la irrigación, estuvo asociado con mejoras en la calidad de los tubérculos en la cosecha. Las plantas sometidas a estrés por agua antes del inicio de la tuberización, produjeron unos pocos tubérculos con coloración oscura poco notoria en el extremo de los tallos, reducción del porcentaje de papas de grado US Nro.2, e incremento en el porcentaje y tamaño de papas de grado US Nro.1. El incremento de la duratión del potential de agua del suelo por debajo de -60 kPa, al comienzo del periodo de crecimiento, fue asociado con la declinatión del rendimiento total en 1985 pero no en 1986. Para obtener un rendimiento óptimo y calidad de procesamiento, la primera irrigatión no debe hacerse antes de la emergencia total de las plantas.

Effects of transitory water stress on potato tuber stem-end reducing sugar and fry color

Potatoes grown for processing in irrigated regions of the Pacific North-west sometimes develop undesirably high concentrations of reducing sugars in tuber stem ends due to hot weather and water stress during tuber development. Such tubers usually produce french fries with dark stem ends or sugar ends. In order to better quantify the relationship between water stress and stem-end sugar levels for Russet Burbank, single episodes of transitory water stress were established by delaying irrigations until soil water potentials ranging from -32 to -107 kPa were reached during early tuber bulking. To determine when the increase in reducing sugars occurred, tubers were sampled before transitory stress, at maximum stress, after stress was relieved with sprinkler irrigation, and post harvest. Reducing sugar concentrations did not increase in tuber stem ends until two weeks or longer after the plant water stress was relieved. Increased reducing sugar concentrations were positively associated with decreased soil water potential (drier soil). Tubers were sliced and fried at harvest and six weeks post-harvest. Decreasing soil water potential (drier soil) was associated with progressively darker fry colors at harvest and post harvest. Significant darkening in the average stem-end fry color light reflectance of tubers at harvest as observed at -80 kPa in 1988 and -69 kPa in 1989. The effect of imposed water stress on tuber stem-end reducing sugar concentrations was most pronounced post harvest.

Irrigation best management practices for potato

Application of the principle of best management practices (BMPs) for potato irrigation maximizes economic use of resources while minimizing environmental disturbances. Potato is a shallow-rooted crop that responds negatively to variations in water supply. Reported research confirms the detrimental effects of small errors in irrigation management on potato production profitability. Potato water use has been thoroughly documented in the literature. Newer irrigation application and control technology is available to growers. Irrigation BMPs for scheduling irrigation by crop evapotranspiration (ETc) and soil water tension (SWT) are presented and discussed. In most cases only refinements of existing potato irrigation systems are needed; growers need to acquire some way to measure ETc or soil water, or preferably both, along with record keeping to track irrigation, ETc, and soil water. An increased increment of management applied to potato irrigation can return greater profits to potato growers while enhancing the sustainability of production by avoiding environmental degradation.ResumenLa aplicación de prácticas de un mejor manejo (BMPs) del riego para el cultivo de papa, maximiza el uso económico de recursos mientras que minimiza las alteraciones del medio ambiente. La papa es un cultivo de raíices poco profundas que responde negativamente a la variación en el abastecimiento de agua. Informes de investigación confirman el efecto nocivo de pequeños errores en el manejo del riego sobre la producción de papa. El uso de agua por el cultivo de papa ha sido ampliamente documentado en la literatura. La más reciente tecnología de aplicación y control del riego está disponible para los que cultivan papa. Se presentan y discuten las BMPs para programar el riego por evapotranspiración del cultivo (ETc) y tensión de agua del suelo (SWT). En la mayoría de los casos sólo se necesita un afinamiento de los sistemas de riego ya existentes; los que cultivan papa necesitan tener la forma de medir la ETc o el agua del suelo o preferiblemente ambos, junto con los registros para rastrear el agua de riego, ETc y agua del suelo. Un mayor incremento en el manejo del riego en la papa puede rendir mayores beneficios, a la vez que la sostenibilidad de la producción mejora evitando la degradación del medio ambiente.

Compositional and enzymatic changes associated with the sugar-end defect in Russet Burbank potatoes.

This study was initiated to determine the starchsugar composition and the activities of relevant enzymes of carbohydrate metabolism in Russet Burbank (cv.) potatoes exhibiting the sugar-end defect. The frequency of sugar-end tubers was increased by applying a single, transient, moisture-deficit stress period following tuberization. The following properties were unique to sugar-end tubers compared to normal tuber tissue. (1) Starch and total solids decreased markedly while glucose content increased 15-fold, (2) The concentration of Suc was markedly lower, (3) Pi was slightly but significantly increased, (4) The activities of UGPase and Susy decreased nearly 3 and 2-fold, respectively, (5) The activity of AGPase decreased 50%, (6) The ratio of STPLase to AGPase shifted over 3-fold in favor of starch mobilization, (7) Basal AcInv activity (assayed in the presence of inhibitor) increased 7-fold during storage, (8) Tuber Glc concentration showed a better correlation to basal Aclnv activity than to total Aclnv activity (inhibitor destroyed), (9) Kinetic analysis suggested that the level and/or effectiveness of the Aclnv inhibitor was decreased in the sugar-end tuber tissue. These results are discussed in relation to metabolic changes which occur in converting a starch storing tuber to one primarily involved with starch mobilization.

Review Of The Sugar End Disorder In Potato (Solanum tuberosum, L.)

Processing quality has become increasingly important to the potato industry. A serious defect in product quality is the physiological disorder known as sugar ends, also referred to as dark ends, jelly ends, translucent ends, and/or glassy ends. Symptoms of the most common type of sugar end include relatively low starch and high sugar content in the basal end of the tuber. Tubers with the sugar end disorder produce French fries that are dark on one end, making the fries unacceptable to consumers. Sugar end potatoes cause time and profit losses at the processing plant and may require blending of loads to meet product specifications, along with the need to change processing protocols. Sugar end can be costly to growers if the tubers have insufficient quality and the crop is rejected for processing. Conditions conducive to the development of sugar ends include high soil temperatures, transitory soil moisture deficits, and insufficient or excess nitrogen fertilization. Tubers are most sensitive to these stresses during early bulking. Historically, several theories have been proposed concerning the mechanism of sugar end development. Research shows that stressed plants produce adequate amounts of assimilate to support continued tuber growth, but accumulate large amounts of sucrose in the basal tissues of the tuber immediately following stress. Accumulated evidence suggests that heat stress and water deficit induce changes in the activities of certain key carbohydrate metabolizing enzymes shifting the tuber from a starch synthesizing function to one of starch mobilization. Genetic resistance to sugar end development is known and the identified traits are highly heritable. This review summarizes sugar end investigations to-date, and presents a list of research-based crop management recommendations that assist potato producers in minimizing the potential for sugar end development in the field.ResumenLa calidad de procesamiento de papa se ha vuelto cada vez más importante para la industria. Un defecto serio en la calidad del producto es el desorden fisiológico conocido como punta azucarada, referido también como punta oscura, punta translúcida y/o punta vítrea. Los síntomas de los tipos más comunes de punta azucarada incluyen bajo contenido relativo de almidón y alto contenido de azúcar en el extremo basal del tubérculo. Los tubérculos con punta azucarada producen papas fritas que tienen un extremo oscuro, haciendo la fritura inaceptable para los consumidores. Las papas con extremo azucarado causan pérdida de tiempo y ganancias a la planta procesadora y puede requerir la mezcla de lotes de papa para satisfacer las especificaciones del producto, además de de la necesidad de cambiar los protocolos de procesamiento. La punta azucarada puede ser costosa para los productores si los tubérculos son de calidad insuficiente y el cultivo es rechazado para procesamiento. Las condiciones que conducen al desarrollo de este desorden incluyen altas temperaturas del suelo, deficiencia transitoria de agua e insuficiencia o exceso de fertilización nitrogenada. Los tubérculos son más sensibles al estrés durante su formación temprana. Históricamente, varias teorías han sido propuestas con relación al mecanismo de desarrollo de punta azucarada. La investigación demuestra que las plantas estresadas producen cantidades adecuadas nutrientes para favorecer el crecimiento continuo del tubérculo, pero que se acumula gran cantidad de sacarosa en el tejido de la base del tubérculo inmediatamente después del estrés. La evidencia acumulada sugiere que el estrés del calor y la deficiencia de agua inducen a cambios en las actividades de ciertos carbohidratos clave que metabolizan enzimas, cambiando así la función de síntesis de almidón del tubérculo por una de movilización del mismo. La resistencia genética al desarrollo de la punta azucarada es conocida y las características identificadas son altamente heredables. Esta revisión resume las investigaciones que se han hecho sobre punta azucarada hasta la fecha y presenta una lista de la investigación basada en recomendaciones de manejo del cultivo que ayude a los productores de papa a minimizar el potencial de desarrollo de punta azucarada en el campo.

Defender: A High-Yielding, Processing Potato Cultivar with Foliar and Tuber Resistance to Late Blight

The potato cultivar Defender is high-yielding, white-skinned, and notable for having foliar and tuber resistance to late blight infection caused byPhytophthora infestans (Mont.) de Bary. It was released in 2004 by the USDA-ARS and the agricultural experiment stations of Idaho, Oregon, and Washington. Defender is suitable for processing into french fries and other frozen potato products directly from the field or from storage. Defender also may be used for fresh markets in regions such as California, where cultivars with long tubers and white skin are traditionally grown. Resistances to late blight and other potato diseases make Defender an ideal candidate for organic potato production. Defender consistently produced greater total and U.S. No. 1 yields than ‘Russet Burbank’ in Idaho trials. In early harvest trials conducted in the western U.S., average total yields of Defender were 17% and 23% greater than yields for ‘Ranger Russet’ and ‘Shepody’, respectively. In full-season trials conducted in the western U.S., Defender averaged 10% and 15% higher yields than Ranger Russet and Russet Burbank, respectively. Specific gravity of Defender is consistently high, with values comparable to those of Ranger Russet; tuber ascorbic acid (Vitamin C) levels are also high. In addition to late blight, Defender also is resistant to tuber early blight (Alternaria solani, (Ellis & G. Martin), L.R. Jones & Grout), potato virus X, and net necrosis; it has moderate levels of resistance to Verticillium wilt (Verticillium dahliae, Kleb), pink rot, foliar early blight, corky ringspot, and Erwinia soft rot. Defender is susceptible to scab (common and powdery) and potato leafroll virus; it has moderate susceptibility to dry rot (Fusarium spp.) and potato virus Y. Susceptibilities to internal necrosis, tuber greening, and blackspot bruise also have been noted, but may be minimized through cultural and harvest practices.ResumenDefender es un cultivar de papa de alto rendimiento, piel blanca y excelente por su resistencia al tizón tardío causado porPhytophthora infestans (Mont.) de Bary, tanto a la infección foliar como a la de los tubérculos. Ha sido liberada el 2004 por USDA-ARS y las Estaciones Experimentales Agrícolas de Idaho, Oregon y Washington. Defender es apropiado para el procesamiento de papa frita y otros productos congelados de papa, directamente del campo o del almacén. Defender puede también ser usado en regiones como California, donde se cultivan tradicionalmente variedades de tubérculos alargados y piel blanca. La resistencia al tizón tardío y otras enfermedades de la papa hace de Defender un candidato ideal para la producción orgánica. Defender tuvo consistentemente un mayor rendimiento de tubérculos de grado “US No. 1” que Russet Burbank en pruebas en Idaho. En ensayos de cosecha temprana realizados en el oeste de EUA, el promedio de rendimiento total de Defender fue de 17 y 23% mayor que el de las variedades Ranger Russet y Shepody respectivamente. En ensayos de ciclo completo realizadas en el oeste, Defender tuvo rendimientos 10 y 15% mayores que Ranger Russet y Russet Burbank respectivamente. El peso específico de Defender es consistentemente alto, con valores comparables a los de Ranger Russet y los niveles de ácido ascórbico (Vitamina C) son también altos. Además de ser resistente al tizón tardío, Defender es también resistente al tizón temprano (Alternaria solani (Ellis & G. Martín) L. R. Jones & Grout), Virus X de la papa y necrosis en red. Tiene niveles moderados de resistencia a marchitez por Verticillium (Verticillium dahliae Kleb.), pudrición rosada, tizón foliar temprano, mancha corchosa en anillo y pudrición blanda causada por Erwinia. Defender es susceptible a la sarna (común y polvorienta) y al virus del enrollamiento; tiene moderada susceptibilidad a la pudrición seca (Fusarium spp.) y al virus Y de la papa. También se ha notado susceptibilidad a necrosis interna, verdeamiento del tubérculo y mancha negra, pero estas pueden minimizarse a través de prácticas culturales.

A Review of Urban Water Body Challenges and Approaches: (1) Rehabilitation and Remediation

AbstractWe review how urbanization alters aquatic ecosystems, as well as actions that managers can take to remediate urban waters. Urbanization affects streams by fundamentally altering longitudinal and lateral processes that in turn alter hydrology, habitat, and water chemistry; these effects create physical and chemical stressors that in turn affect the biota. Urban streams often suffer from multiple stressor effects that have collectively been termed an “urban stream syndrome,” in which no single factor dominates degraded conditions. Resource managers have multiple ways of combating the urban stream syndrome. These approaches range from whole-watershed protection to reach-scale habitat rehabilitation, but the prescription must be matched to the scale of the factors that are causing the problem, and results will likely not be immediate because of lengthy recovery times. Although pristine or reference conditions are far from attainable, urban stream rehabilitation is a worthy goal because appropriate act...

Placement of soil moisture sensors in sprinkler irrigated potatoes

Potato (Solanum tuberosum L.) is particularly sensitive to soil water potential below −50 to −60 J kg−1 during tuber development. Soil water must also be carefully monitored to irrigate efficiently and to minimize nitrate leaching associated with over-irrigation. Water distribution in and below potato hills during and following sprinkler irrigation was monitored using granular matrix sensors (Watermark Model 200, Irrometer Co., Riverside, CA) placed in 0.10 m × 0.15 m cross-sectional grids down to 0.6-m depth below the soil surface. Each grid consisted of 26 sensors. Sensor electrical resistance had been calibrated to soil water potential. During one test, soil water potential was intentionally lowered to levels drier than ideal for potato to emphasize soil wetting and drying patterns. Over the 26 locations in the grids, the soil water potential averaged −33 J kg−1 over a six week period, with sprinkler irrigations evenly rewetting the upper 0.2 m of the hill. On average, the driest locations were the top of the hill, directly under the hill, and below the furrow with wheel track compaction. Ideal sensor locations for monitoring soil water status and scheduling irrigations are offset 0.15 m from the center of the hill and 0.1 to 0.2 m deep. Sensors installed in silt loam soil responded within four hours to wetting and within 12 hours to drying, the shortest increments of time measured.CompendioLa papa (Solanum tuberosum L.) durante el desarrollo de los tubérculos es particularmente sensible al potencial de agua del suelo por debajo de −50 a-60J kg1. El agua del suelo requiere también de un seguimiento cuidadoso, para irrigar eficientemente y minimizar la percolation de los nitratos asociada con la irrigación excesiva. Se hizo un seguimiento de la distributión del agua, en y por debajo de los surcos de papa, durante y después de la irrigación por aspersión, usando sensores de matrix granular (Watermark Model 200, Irrometer Co., Riverside, CA) colocados en mallas transversales de 0.10 m × 0.15 m, a 0.6 m debajo de la superficie del suelo. Cada malla consistía de 26 sensores. La resistencia eléctrica de los sensores había sido calibrada al potencial de agua del suelo. Durante una prueba, el potencial de agua del suelo fue reducido intencionalmente a niveles mas secos que el ideal para la papa, para enfatizar las formas de humedecimiento y secamiento del suelo. De los 26 puntos en las mallas, el potencial de agua del suelo promedió −33 J kg-1 en un periodo de seis semanas, con irrigaciones por aspersion que mojaban nueva y uniformemente los 0.2 m superiores del surco. En promedio, los puntos más secos fueron la parte superior del surco, la parte directamente bajo la cumbre del surco y la parte baja del surco compactada por el paso de las ruedas. La localización ideal de los sensores para efectuar el seguimiento de las condiciones de humedad del suelo y del programa de irrigaciones esta a 0.15 m del centro del surco y a 0.1 a 0.2 m de profundidad. Los sensores instalados en suelo migajon arcilloso respondieron al humedecimiento en cuatro horas y en 12 horas al secamiento, los incrementos más cortos de tiempo medidos.

Umatilla Russet: A full season long Russet for processing and fresh market use

Umatilla Russet, a moderately late maturing variety especially suitable for frozen French fry processing but also acceptable for tablestock use (boiling, and baking), was jointly released by the Agricultural Experiment Stations of Oregon, Idaho, and Washington and the U.S. Department of Agriculture in 1998. Umatilla Russet was evaluated in irrigated trials in Oregon from 1988 to 1997, and in western regional trials from 1989 to 1991. Total yields were similar to those of Russet Burbank, but Umatilla Russet produced higher marketable yields. In three years of regional trials at up to 13 locations in seven western states, Umatilla Russet averaged 40.5 Mg/ha compared with 32.4 Mg/ha for Russet. Burbank. Umatilla Russet fry color and specific gravity are consistently equal to or better than for Russet Burbank. Umatilla Russet is less susceptible toVerticillium wilt than Russet Norkotah, less susceptible to net necrosis than Russet Burbank, and resistant to PVX. It is susceptible to PLRV and expresses foliar symptoms of PVY more clearly than Russet Norkotah. Umatilla Russet is less susceptible to tuber infection and decay caused byPhytophthora infestans than Ranger Russet and Russet Norkotah. Umatilla Russet is less susceptible to hollow heart, brown center, growth cracks, and sugar ends, but more susceptible to blackspot and shatter bruise than Russet Burbank