White Pearl-A Chipping Potato Variety with High Level of Resistance to Cold Sweetening

American Journal of Potato Research, May/Jun 2006 by Groza, H I, Bowen, B D, Stevenson, W R, Sowokinos, J R, Et al

ABSTRACT

White Pearl is a chipping cultivar with high level of resistance to cold sweetening. The cold-chipping capacity of White Pearl is better than the current chipping cultivars, including Atlantic, Snowden and NorValley. White Pearl has low glucose content and good chip color when processed directly after a 7-month storage period at 3.3 to 5.5 C. White Pearl tubers are similar to Snowden with a round oval shape, light netting, shallow eyes, white flesh, small to medium size, uniform shape, and are practically free of external and internal defects. The yield and specific gravity of White Pearl are medium. White Pearl is similar to Snowden in susceptibility to early blight, pink rot and soft rot, but it is slightly more resistant to common scab. White Pearl vines are susceptible to late blight, but can be managed effectively with fungicides. White Pearl is more sensitive to blackspot bruise than Atlantic or Snowden at 7.2 C, but is more resistant at higher temperatures. White Pearl is sensitive to metribuzin (Sencor), but not rimsulfuron (Matrix) or sulfentrazone (Spartan).

RESUMEN

White Pearl es una variedad para fritura en hojuelas con nivel alto de resistencia al endulzamiento por efecto del fr�o. La capacidad de fritura despu�s de almacenado en fr�o de White Pearl es mejor que las variedades que com�nmente se usan para hojuelas incluyendo Atlantic, Snowden y NorValley. White Pearl tiene bajo contenido de glucosa y buen color de hojuelas cuando se procesa directamente despu�s de siete meses de almacenamiento a 3.3 a 5.5 C. Los tub�rculos de White Pearl son similares a los de Snowden, tienen forma redonda ovalada, ligeramente reticulados, ojos poco profundos, pulpa blanca, de tama�o peque�o a mediane, uniformes y est�n pr�cticamente libres de defectos internes y externes. White Pearl es de rendimiento y gravedad espec�fica media. Es similar a Snowden en susceptibilidad al tiz�n temprano, pudricion rosada y pudricion blanda, pero es ligeramente m�s resistente a la sarna com�n. El follaje de White Pearl es susceptible al tiz�n tard�o, pero esta enfermedad se puede manejar en forma efectiva con fungicidas. White Pearl es mas sensible a la mancha negra causada por magulladura que Atlantic o Snowden a 7.2 C, pero es m�s resistente a temperatures mayores. White Pearl es sensible al metribuzin (Sencor) pero no al rimsulfuron (Matrix) � a sulfentrazona (Spartan).

Accepted for publication 12 January 2006.

ADDITIONAL KEY WORDS: Solanum tuberosum, chipping, cold sweetening

INTRODUCTION

'White Pearl' (W1355-1) is a round white potato variety with good chipping potential due to its high level of resistance to cold sweetening. The cross and selection of White Pearl were conducted at the Rhinelander Agricultural Research Station, the University of Wisconsin-Madison. White Pearl was derived from a cross using 'Snowden' as a female and S440 as a male (Figure 1). Snowden was released by the University of Wisconsin-Madison and is a well-known variety for its coldsweetening resistance. The pedigree of Snowden includes wild species Solatium chacoense through 'Lenape'. S440 is a coldsweetening resistant breeding line. The pedigree of S440 includes wild species Solanum tarijense (Figure 1). The cross was made in 1991. White Pearl was in the seedling stage in 1992, single-hill plots in 1993, four-hill plots in 1994, eight-hill plots in 1995, first year of replicated trials at Hancock and Rhinelander in 1996, rapid multiplication field in 1997, second year of replicated trials in Hancock and Rhinelander in 1997, Wisconsin State trials in Hancock and Antigo in 1998, 2001, and 2002, North Central Regional Trials from 1998 to 2000, and the Snack Food Trial from 2001 to 2003. White Pearl was introduced into the Wisconsin seed Certification Program as W1355-1 in 2002.

VARIETY DESCRIPTION

Plant Vine and Foliage Characteristics

Haulm: semi-erect growth habit with intermediate stem type, medium to strong vines with a medium-sized uniform canopy (Figure 2). White Pearl has full-season maturity estimated at 130 days or 10 to 12 days later than Snowden. White Pearl is slow to emerge, result in delayed canopy closure of about 2 weeks later than Snowden or 'Russet Burbank'. Stems: two to four stems per plant that are branched with medium anthocyanin coloration and weak stem wings. Leaves: medium to dark green (7.5 GY 5/4 Munsell Color Chart) with sparse to medium short pubescence, a medium open silhouette, and small leaf stipule size. Terminal leaflets have a medium ovate shape with acuminate tip, cordate base shape and medium margin waviness. Leaves typically have three pairs of primary leaflets that are small to medium in size and are broadly ovate. Each leaf also has three pairs of secondary and tertiary leaflets. Petioles have weak anthocyanin coloration. Flowers: three to four inflorescences per plant. Each inflorescence has six to eight flowers per inflorescence that emerge from a long peduncle. The calyx has no anthocyanin coloration. The corolla is white with a pentagonal shape. The stigma is capitate and pale green in color (2.5 GY 8/8 Munsell). Anthers have a narrow cone shape and are yellow (2.5 Y 8/10 Munsell) with few pollen. Few berries are produced on each plant.