American Journal of Potato Research

, Volume 95, Issue 5, pp 526–538 | Cite as

Efficacy of Seed Aging and Gibberellin Treatments for Manipulating Apical Dominance, Tuber Set and Size Distribution of cv. Shepody

  • Cody J. Dean
  • Lisa O. Knowles
  • N. Richard KnowlesEmail author


The cultivar Shepody has excellent early processing qualities and produces above average tuber yields but sets relatively few tubers that often become excessively large relative to market demand. Optimizing tuber set and size of Shepody for seed and frozen processing markets currently entails adjusting in-row spacing and vine kill date. However, arresting tuber growth by vine killing for size control sacrifices yield potential. Aging seed by storing at 12, 22, and 32°C for 80-, 450-, and 900-degree days, or gibberellin (GA) treatments, were evaluated as more direct approaches for modulating stem number (apical dominance), tuber set, and size distribution relationships. Shepody proved to be inherently resistant to high temperature-induced age-priming treatments. In contrast to other cultivars studied previously, age-priming Shepody seed during storage had no effect on plant emergence and the resulting increases in stem number, tuber set, and associated decreases in average tuber weight were marginal. By contrast, GA applied as seed dip or spray effectively hastened plant emergence, reduced apical dominance, increased tuber set, and decreased average tuber size. The magnitude of these GA-induced effects depended on concentration and application technique (seed dip versus spray). For frozen processing, GA applied as a seed dip at 1 mg L-1 added an additional tuber per plant and decreased average tuber size by 15% without affecting U.S. No. 1 tuber yields and gross returns; however, 2 and 3 mg L-1 GA decreased U.S. No. 1 tuber yields and crop value by an average of 16 and 14%, respectively. Spray applications of 2–6 mg L-1 GA also reduced U.S. No. 1 tuber yield and frozen processing value. Conversely, the increase in tuber set (1.5 tubers plant-1) and associated 25% reduction in average tuber weight induced by 2 mg L-1 GA applied as either dip or spray increased gross crop values on a seed contract by 25 and 38%, respectively. The differential efficacies of dip versus spray applications of GA on tuber set and size distribution were likely attributable to differences in GA deposition on the seed. Applying low concentrations of GA to cut seed of Shepody as either a dip (1–2 mg L-1) or spray (2 mg L-1) effectively modulated tuber set and size to significantly increase gross returns for seed, and to better satisfy the needs of processors for more moderate size tubers.


Solanum tuberosumSeed physiological age Gibberellic acid Stem number Tuber number Crop value 


La variedad Shepody tiene excelentes cualidades para proceso temprano y produce rendimiento de tubérculos por encima del promedio, pero forma relativamente pocos tubérculos que a menudo son excesivamente grandes en relación a la demanda del mercado. La optimización de la formación y tamaño de Shepody para semilla y para mercados de procesamiento congelado actualmente implica ajustes en espaciamiento en el surco y en fechas de quema del follaje. No obstante, la disminución del crecimiento del tubérculo mediante la quema del follaje para controlar el tamaño sacrifica el rendimiento potencial. Se evaluaron tratamientos de envejecimiento de la semilla mediante el almacenamiento a 12, 22, y 32°C durante 80-, 450-, y 900- días grado, o con giberelina (GA) como enfoques más directos para modular las relaciones entre el número de tallos (dominancia apical), amarre de tubérculo y distribución de tamaños. Shepody demostró ser inherentemente resistente a los tratamientos de inducción de iniciación de envejecimiento por temperatura. En contraste con otras variedades estudiadas previamente, la semilla de Shepody con iniciación de envejecimiento durante el almacenamiento no tuvo efecto en la emergencia de la planta y en los aumentos resultantes en número de tallos y amarre de tubérculos, y fueron marginales las disminuciones asociadas en el peso promedio de tubérculo. En contraste, la aplicación de GA por inmersión de la semilla o como aspersión aceleró efectivamente la emergencia de la planta, redujo la dominancia apical, aumentó el amarre de tubérculo y disminuyó el promedio de su tamaño. La magnitud de estos efectos inducidos por el GA, dependieron de la concentración y técnica de aplicación (inmersión de semilla contra aspersión). Para procesamiento congelado, el GA aplicado en inmersión a 1 mg L–1 agregó un tubérculo adicional por planta y disminuyó el promedio del tamaño del tubérculo en un 15% sin afectar los rendimientos de tubérculo U. S. No. 1 y la recuperación bruta; no obstante, 2 y 3 mg L–1 de GA disminuyeron el rendimiento de tubérculos U. S. No. 1 y el valor del cultivo en un promedio de 16 y 14%, respectivamente. Las aplicaciones por aspersión de 2–6 mg L–1 de GA también redujeron el rendimiento de tubérculo U. S. No. 1 y el valor del procesamiento congelado. A la inversa, el aumento en el amarre de tubérculo (1.5 tubérculos por planta–1) y la asociación en la reducción del 25% en el promedio de peso de tubérculo inducida por 2 mg L–1 de GA aplicado ya fuera por inmersión o aspersión, incrementó los valores brutos del cultivo en un contrato de semilla en 25 y 38%, respectivamente. Las eficacias diferenciales de las aplicaciones de GA en inmersión contra la aspersión en el amarre de tubérculo y distribución del tamaño fueron atribuibles probablemente a las diferencias en la deposición del GA en la semilla. La aplicación de bajas concentraciones de GA a semilla cortada de Shepody ya fuera como inmersión (1–2 mg L–1) o en aspersión (2 mg L–1), moduló efectivamente el amarre y tamaño del tubérculo a aumento significativo de recuperación bruta para semilla, y para una mejor satisfacción de las necesidades de los procesadores respecto a tamaño más moderado de tubérculos.



Financial support was provided by the Washington State Potato Commission, Northwest Potato Research Consortium, and the USDA Specialty Crop Block Grant program.


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Copyright information

© The Potato Association of America 2018

Authors and Affiliations

  • Cody J. Dean
    • 1
  • Lisa O. Knowles
    • 1
  • N. Richard Knowles
    • 1
    Email author
  1. 1.Postharvest Physiology and Biochemistry Laboratory, Department of HorticultureWashington State UniversityPullmanUSA

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