Boulder: A round white multipurpose potato variety

Amer J of Potato Res (2003) 80:345-352 345

Boulder: A Round White Multipurpose Potato Variety

D. S. D o u c h e s 1., J. C o o m b s 1, K. J a s t r z e b s k P , R. H a m m e r s c h m i d t 2,

W. W. Kirk 2, C. L o n g ~, R. W. C h a s e 1, a n d S. S n a p p 1

Department of Crop and Soil Sciences, Michigan State University, E. Lansing, MI 48824. 2Department of Plant Pathology, Michigan State University, E. Lansing, M] 48824.

*Corresponding author: Tel: 517-353-3145; Fax: 517-353-5174; Email: [email protected]

ABSTRACT

Boulder is a round whi te se lec t ion with medium spe-

cific gravi ty tha t can be used in both the t ab les tock and

chip-processing markets . The tubers will chip process

out-of- the-f ie ld and f rom 10 C storage. The t ube r s o f

Boulder are large in size wi th a low incidence o f i n t e rna l

defects . Boulder was t e s t e d in Michigan S ta te Univers i ty

tr ials , the Nor th Cent ra l Regional tr ials, on-farm t r ia ls

in Michigan and o the r out -of -s ta te rep l ica ted agronomic

tr ials . Under i r r iga ted condi t ions in Michigan, the yield

is s imi lar to or b e t t e r than Atlant ic , but specific grav i ty

is less. Boulder has a ful l -season vine ma tu r i ty t h a t is

s imi lar to Snowden, but the tubers size early. Based

upon our tr ials , an in-row spacing o f less than 25.4 cm to

reduce the percen tage o f overs ize tubers is recom-

mended. In s imula ted bru ise tes ts , Boulder had less

b l a c k s p o t b ru i s ing t h a n A t l an t i c , bu t was m o r e

b lackspot suscept ible than Onaway. Based upon five

years o f tr ials , Boulder has res i s tance to scab tha t is

g r ea t e r than Atlant ic , but less than Onaway.

RESUMEN

Boulder es una selecci6n r edondeada con c~iscara o

pie l b lanca y de gravedad especif ica mediana, que puede

se r u t i l izada t an to para uso de mesa y para herv i r como

tambi~n para mercado de p rocesamien to de hojuelas .

Los tub~rculos pueden ser p rocesados en hojue las direc-

t a m e n t e del campo o d e l a lmacenamien to a 10 C. Los

tub~rculos de Boulder son de tamafio grande con una

baja incidencia de defec tos in ternos . Boulder rue evalu-

Accepted for publication 21 July 2003. ADDITIONAL KEY WORDS: Solanum tuberosum.

ada en ensayos de la Univers idad de Michigan, ensayos

de la regi6n no r t e central , ensayos en flncas de agricul-

t o re s y o t ros ensayos repl icados rea l izados fuera del

estado, pa ra carac ter i s t icas agron6micas. Bajo condi-

ciones de i r igaci6n en Michigan, el r end imien to es simi-

lar o me jo r al de la var iedad Atlant ic , pe ro la gravedad

especif ica es menor. Boulder t i ene madur4z de la vid de

t emporada comple ta muy s imilar a la var iedad Snowden,

pe ro de tuber izac i6n y l lenado de tub~rculos temprana.

Basado en nues t ros ensayos, r ecomendamos sembrar los

tub~rculos a menos de 25.4 cm en t re p lan tas en el surco

o camell6n para reduc i r el po rcen ta j e de tub~rculos

demasiado grandes. En la p rueba de magul ladura simu-

lada, Boulder t en ia menos mancha en la piel al mag~fllar

que At lant ic y e ra m~s suscept ible a mancha en la piel

que Onaway. Basado en cinco afios de ensayos, Boulder

es m~s res i s t en te a la sarna de la papa que Atlantic, pero

menos res i s t en te que Onaway.

BACKGROUND

Boulder is a new round white potato variety (Solanum

tuberosum L.) developed at Michigan State University that can

be grown for either the tablestock or chip-processing markets.

Boulder was evaluated as seedling number MSF373-8. It is a

selection from a cross made in 1993 between the moderately

scab-resistant breeding line MS702-80 and chip-processing

breeding line NY88 from Cornell University for the purpose of

breeding scab-resistant chip-processing varieties. The pedi-

gree of Boulder is described in Figure 1. The name Boulder

was chosen to describe the set of large tubers with low inci-

dence of internal defects.

Boulder is a round white chip-processing variety with a

small set of large, bright-skinned tubers (Figure 2). The tubers

have a low level of internal defects. The primary strength of

346 AMERICAN JOURNAL OF POTATO RESEARCH Vol. 80

this variety is its high yield potential combined with a small set

of large A-size tubers across many environments. In addition

to trials in Michigan (breeding program research and on-farm

grower trials), Boulder was tested In the North Central

Regional trials.

~ A t l a n t i c

- M S 7 0 2 - 8 0

t _ _ W i s c h i p

B o u l d e r

(MSF373-8)

FIGURE 1. Ped igree o f B o u l d e r

N Y 8 8

- N Y 7 4

t - QlSS-3

- B 6 5 9 5 - 5

- N Y 4 8

- K 3 4 9 - 7

- 6t lS9

The seedling generation was grown in 1994, followed by

two years of selection and seed multiplication at the Lake City

Experiment Station, Lake City, MI. Seed increase was located

at the Lake City Experiment Station. Since 1998, Boulder has

been tested in replicated agronomic trials at the Montcalm

Research Farm, Entrican, MI, and in the scab nursery at the

Michigan State University Soils Farm, East Lansing, MI. In

2000 it was entered into grower on-farm trials in Michigan and

the North Central Regional Trial. In 2001 Boulder was placed

into commercial seed production.

V A R I E T A L D E S C R I P T I O N

Plant Vine and Foliage Growth habit: Medium to tall height, semi-erect with a

balance between stems and foliage visible. Stems: Antho-

cyanin medium, wings are medium. Leaves: Medium-green

(Royal Horticulture Society [R.H.S.] Color Chart value 137A)

with medium dense, short pubescence; open leaf silhouette;

petiole anthocyanin coloration is weak; leaf stipules are

medium sized. Terminal leaflets: Medium ovate with acumi-

nate tip and cordate base, with slight leaflet margin waviness.

IMmary leaflets: Five pairs per leaf, narrowly ovate, with

acuminate tip and cordate base. Secondary and tertiary

leaflets: four pairs. Vine maturity: full season (145 days).

Inflorescence Twenty to 30 with an average of 24 per plant; mean of 18

florets per inflorescence. Corolla: Semi-stellate in shape with a

violet color (R.H.S. Color Chart value 84C). Calyx: Antho-

cyanin coloration medium. Anthers: Narrow cone shape with

a yellow-orange color (R.H.S. Color Chart value I?A). Stigma:

Capitate and green (R.H.S. Color Chart value 147B). Fertility:

Pollen shed is abundant and female fertility is average. Fruit

set in the field is low.

FIGURE 2. Tuber s a m p l e o f B o u l d e r f r o m a f i e ld t r ia l a t the Michigan S t a t e U n i v e r s i t y M o n t c a l m R e s e a r c h Farm, Entr ican , Michigan.

Tubers Shape: Round. The average tuber length x width x thick-

ness is 91 mm x 78 mm x 61 mm with an average weight of 316

g. Skin: Bright and smooth with a tan color (R.H.S. Color Chart

value 162A). Eyes: Intermediate eye depth, evenly distributed

with an average 9 eyes/tuber; eyebrows have a slight promi-

nence. Flesh: Cream (R.H.S. Color Chart value llD). Dor-

mancy: Medium, comparable to Atlantic. The light sprouts are

characterized by a strong anthocyanin base (Figure 3).

2003 D O U C H E S e t al.: BO U L D E R 347

AGRONOMIC PRODUCTION

Field expe r imen t s we re c o n d u c t e d at the Mon tca lm

Resea rch Fa rm in Entr ican, MI, to measu re to ta l and mar-

kemble yields, to de t e rmine t u b e r size distr ibution, specif ic

gravity, and to evaluate b l ackspo t bruising, tube r appearance ,

and ix~cidence of ex terna l and in terna l defects. Boulder ' s agro-

nomic pe r fo rmance has b e e n t e s t ed for five years at the Mont-

ca lm Resea rch Farm, two years in the Nor th Central Regional

trials, and th ree years in on-farm trials in Michigan. Five years

of ear ly ha rves t (97-104 days) and full s ea son (122-144 days)

ag ronomic da ta at the Michigan State Universi ty Mon tca lm

Resea rch Fa rm for Boulder in compar i son to Atlant ic a n d

Onaway are summar ized in Tables 1 and 2, respectively. The

yield of marke tab le tube r s for Boulder was equivalent to or

b e t t e r t han Atlantic (process ing check variety) and Onaway

( t ab les tock c h e c k variety) in b o t h early and late harves ts .

Based u p o n our trials (da ta no t shown) , we r e c o m m e n d a n in-

r ow spac ing of less t han 25.4 c m to reduce the pe rcen t age of

oversize tubers .

FIGURE 3. Light sprouts o f Boulder.

TABLE 1--Early harvest agronomic performance trials at the Michigan State University Montcalm Research Farm, Entrican, Michigan.

Potato mt ha -1 Percent of Total I Specific Chip Tuber Quality (%)3 Cultivar US#1 Total US#1 Bs As OV PO Gravity Score -~ HH VD IBS BC

1998 (98 days to harvest) Boulder 48 51 95 2 43 52 3 1.071 1.0 8 0 0 0 Atlantic 39 44 89 9 81 8 2 1.081 1.0 15 0 0 0 Onaway 33 39 85 11 81 4 4 1.063 3 10 3 0 LSD005 7 7 0.003

2000 (104 days to harvest) Boulder 52 56 92 2 52 40 5 1.075 1.5 15 0 0 0 Atlantic 46 52 89 8 75 14 3 1.084 1.0 43 0 3 0 LSD006 6 6 0.004

2001 (98 days to harvest) Boulder 36 39 92 5 73 19 3 1.074 20 0 0 0 Onaway 50 54 93 6 89 4 1 1.071 0 0 0 0 LSDoo 5 7 7 0.007

2002 (97 days to harvest) Boulder 27 28 97 1 66 32 2 1.068 1.5 0 0 0 0 Atlantic 30 33 90 8 85 5 3 1.079 1.0 30 0 0 0 LSD~05 4 4 0.002

1Size distribution: B: <5.1 cm, A: 5.1-8.3 cm, OV: >8.3 cm, PO: Pickouts 2Snack Food Association Chip Score Ratings 1-5; 1 = Excellent; 5 = Poor, _>2.5 = Unacceptable. ~'uber quality: HH: Hollow Heart, VD: Vascular Discoloration; IBS: Internal Brown Spot; BC: Brown Center. Percentage of 40 oversize (>8.3 cm) tubers cut. Mean comparisons were done using Fishers Least Significant Difference (c¢ = 0.05). The plots were 7 m in length and spacing between plants was 30.5 cm. Inter-row spacing was 86.4 cm. Total nitrogen fertilization during the season was 200 kg/Ha. The Montcalm site is a McBride sandy loan soil with supplemental overhead irrigation.


TABLE 2--FuU season agronomic performance trials at the Michigan State University Montcalm Research Farm,

Entrican, Michigan.

Potato mt ha 1 Percent of Total 1 Specific Chip Tuber Quality (%)~ Cultivar US#1 Total US#1 Bs As OV PO Gravity Score 2 HH VD IBS BC

1998 (133 days to harvest) Boulder 52 54 96 2 37 59 2 1.073 1.0 10 3 0 0 Atlantic 45 50 91 8 77 13 1 1.081 1.0 13 3 0 0 Onaway 30 38 80 18 79 1 2 1.060 3.0 0 10 0 0 LSD0.05 7 7 0.003

1999 (122 days to harvest) Boulder 45 48 95 5 73 22 1 1.083 1.5 0 0 0 0 Atlantic 35 42 83 14 79 4 4 1.089 1.0 5 0 0 0 Onaway 27 38 72 25 72 0 2 1.064 4.0 0 15 0 0 LSD0.05 5 5 0.002


2000 (146 days to harvest) Boulder 58 62 94 2 37 57 4 1.076 1.5 23 0 0 0 Atlantic 47 54 87 7 59 27 6 1.086 1.0 20 0 5 3 LSD00 ~ 9 8 0.003

2001 (128 days to harvest) Boulder 44 48 93 4 54 39 3 1.072 1.0 8 0 0 3 Atlantic 38 43 87 11 73 14 2 1.080 1.5 23 5 28 20 LSD00~ 9 8 0.002

2001 (14t days to harvest) Boulder 52 55 94 3 59 34 4 1.072 13 0 0 3 Onaway 43 47 91 7 86 5 3 1.063 0 20 0 0 LSD005 6 6 0.003


1Size distribution: B: <5.1 cm, A= 5.1-8.3 cm, OV: >8.3 cm, PO: Pickouts -~Snack Food Association Chip Score Ratings 1-5; i = Excellent; 5 = Poor; >2.5 = Unacceptable. ~uber quality: HI-I: Hollow Heart, VD: Vascular Discoloration; IBS: Internal Brown Spot; BC: Brown Center. Percentage of 40 oversize (>8.3 cm) tubers cut. Mean comparisons were done using Fisher's Least Significant Difference (c¢ = 0.05). The plots were 7 m in length and spacing between plants was 30.5 cm. Inter-row spacing was 86.4 cm. Total nitrogen fertilization during the sea- ._ son was 200 kg/Ha. The Montcalm site is a McBride sandy loan soil with supplemental overhead irrigation.

Under our trial conditions, the oversized tubers of Atiantic

have a tendency to express hol low heart. Despite the high per-

centage of oversize tubers (22% -69°A), Boulder is less suscepti-

ble to this condit ion (late harvest trials). In the five years of

trials, low percentages of hol low hear t were observed (0%-23%)

in oversized tubers, whereas hollow heart in Atlantic ranged

f rom 5%-45%. Incidence of vascular discoloration, internal

b rown spot and b rown center in Boulder is also very low,

meanwhile Atlantic is susceptible to internal b rown spot, and

b rown cen te r (Tables 1 and 2). 2hber specific gravity of Boul-

der grown under irrigation in Michigan trials was lower than

Atlantic, but higher than Onaway. In the North Central Regional

trials wi th irrigation, Boulder's yield per formance was similar

to Atlantic (Table 3). Unlike Michigan, specific gravity of Boul-

der in the North Central Regional trials was above the 1.080

threshold for chip-processing, but significantly lower than

2003 D O U C H E S e t al.: BOULDER 349

TABLE 3---Yield and specific gravity of Boulder from eight irrigated locations in the North

Central Regional Potato Trials.

Tuber Quality 1 Potato mt ha ~ Percent Specific Percent (%) Cultivar US#1 Total US#1 Gravity Mat 2 HH VD IBS BC

2000 Boulder 38 44 86 1.085 3.7 3 4 0 0 Atlantic 40 47 88 1.090 3.3 8 4 2 0 LSD00~ NS NS 0.005 0.3

2001 Boulder 43 50 84 1.083 3.8 4 1 0 1 Atlantic 39 48 83 1.091 3.1 16 2 6 3 LSD0.05 NS NS 0.004 NS

1Tuber quality: HH: Hollow Heart, VD: Vascular Discoloration; IBS: Internal Brown Spot; BC: Brown Center. Percentage tuber internal defects. 2Vine maturity: 1 = early; 5 = late. Average of six irrigated locations. Mean comparisons were done using Fishers Least Significant Difference (a = 0.05).

TABLE 4---Chip processing quality of Boulder in

comparison to Atlantic from 2001 North Central

Regional Trials from the USDA-ARS Potato

Research Worksite at East Grand Forks, MN.

OTF ~ OTF Specific Location Agtron 2 Visual 3 Gravity

BOULDER Alberta, Canada 48 3 1.091 Manitoba, Canada 48 3 1.096 Michigan, USA 65 1 1.095 Minnesota, USA 61 1 1.091 North Dakota, USA 58 2 1.156 Nebraska, USA 61 1 1.087 Ohio, USA 60 1 1.086 Ontario, Canada 64 1 1.086 Wisconsin, USA 69 3 1.099 MEAN 59 1.8 1.099

ATLANTIC Alberta, Canada 56 2 1.103 Manitoba, Canada 56 2 1.106 Michigan, USA 63 1 1.101 Minnesota, USA 57 2 1.086 North Dakota, USA 55 2 1.081 Nebraska, USA 60 1 1.090 Ohio, USA 63 1 1.097 Ontario, Canada 64 1 1.098 Wisconsin, USA 52 3 1.088 MEAN 58 1.7 1.094

LSD005 NS NS NS

~OTF: Out of the field 2Agtron values provided by USDA-ARS Potato Research Worksite at East Grand Forks, MN. 3Visual Rating using the Snack Food Association Chip Score Ratings 1-5; 1 = Excellent; 1..5-2.0 = Acceptable, 2.5-5.0 = Unacceptable. Mean comparisons were done using Fisher's Least Significant Difference (c~=0.05).

At lant ic (Tables 3 and 4). In b o t h years, t he v ine matur i ty for

Boulder was l a t e r t h a n Atlantic. Bou lde r w a s inc luded in on-

f a rm tr ials in Michigan f rom 2000 to 2002. Table 5 summa-

r izes the a g r o n o m i c p e r f o r m a n c e of s e v e n locat ions . Boulder

h a d a yield s imi la r to Onaway in the t a b l e s t o c k t r ia ls and to

Atlant ic in the p r o c e s s i n g trials, bu t Bou lde r had f rom 35% to

60°/5 overs ize tubers . Boulder was also eva lua ted in Nor th

Carol ina a n d F lor ida in 2001. The to ta l a n d m a r k e t a b l e yield

of Boulder was s imi lar to Atlant ic in t he se loca t ions (da ta no t

shown) .

Tuber Quality

Ctfip-processing quality of Bou lde r was a s se s sed on

tubers f rom Montca lm Research Fa rm trials, the Nor th Central

Regional trials, and in the Michigan Po ta to Indus t ry Demon-

s t ra t ion Storage. Boulder p roduces a large pe rcen tage of over-

size tube r s a t 30.5 cm in-row spacing, t hus t ighter spacing

should be u sed in commerc ia l product ion. Tables 1 and 2 also

compare Boulder to Atlant ic f rom 1998 to 2002 f rom the Mont-

ca lm Research Fa rm trials; ch ip-process ing out of the field in

b o t h early and late ha rves t s was accep tab le for Boulder and

Atlantic. Chip-process ing in the Nor th Centra l Regional trials

is summar ized in Table 4. On average, the Agtron and visual

chip color were accep tab le to industry. Tuber samples were

also s tored at the Michigan Pota to Indus t ry Commiss ion Com-

mercial Demons t r a t ion Storage in Montcalm, MI, for a 50 F

target s torage tempera ture . Table 6 shows the SFA chip scores

and mon th ly s torage t e m p e r a t u r e s f rom N o v e m b e r 2000

th rough June 2001. In this study, the chip color of Boulder was

350 AMERICAN JOURNAL O F POTATO R E S E A R C H Vol. 80

TABLE 5---Agronomic performance of Boulder from Michigan on-farm trials.

Potato mt ha -~ Percent of Total ~ Specific Cultivar US#1 Total US#1 Bs As OV PO Gravity

2000 Processing Trials (Four locations) Boulder 61 64 95 4 37 58 1 1.078 Atlantic 50 54 93 6 74 19 1 1.091 LSD0.06 NS NS 6 0.003

2000 Tablestock Trials (Three locations) Boulder 67 69 97 3 37 60 0 1.075 Onaway 50 54 89 7 65 23 5 1.071 LSD0~ NS NS NS NS

2001 Tablestock Trials (Two locations) Boulder 59 62 96 2 49 46 3 1.075 Onaway 53 58 91 7 75 16 2 1.068 LSD0.05 NS NS NS NS

2002 Processing Trials (Four locations) Boulder 39 41 96 3 61 35 1 1.073 Atlantic 35 41 84 16 81 3 0 1.072 LSD0. ~ NS NS 20 NS

2002 Tablestock Trials (Thi-ee locations) Boulder 39 40 97 3 55 42 0 1.073 Onaway 39 43 91 6 78 13 3 1.064 LSD005 NS NS NS NS

~Size Distribution: B: <5.1 cm, A: 5.1-8.3 cm, OV: >8.3 cm, PO: Pickouts Mean comparisons were done using Fisher's Least Significant Difference (a = 0.05).

TABLE 6---Chip Color Values (SFA scale*) from Michigan Potato Industry Commission Demonstration Storage, Montcalm Research Farm, Entrican, Michigan.

Sample Dates: 11/3/2000 12/6/2000 1115/2001 2/9/2001 3/1/2001 4/2/2001 5/4/2001 6/1/2001 6/15/2001

Potato Bin Temperature (C (F)): Line: 14 (58) 11 (51) 12 (53) 12 (53) 12 (54) 10 (50) 11 (51) 12 (53) 13 (55)

Boulder 1.5 1.5 2.0 1.0 1.5 1.5 1.5 1.5 2.0 Atlantic 1.5 1.5 1.5 1.5 1.5 1.5 1.0 2.0 2.0

tSnack Food Association Chip Score Ratings 1-5; 1 = Excellent; 1.5-2.0 = Acceptable, 2.5-5.0 = Unacceptable. Chip scores were from two-slice samples from five tubers of each line collected at each sample date. Tubers placed in storage October.

accep tab le t h roughou t the s torage season and c o m p a r a b l e to

Atlantic.

To evaluate b l ackspo t bruise, t ube r samples f rom Boul-

der, Atlantic, and Onaway were col lected for a s imula ted

b ru i se tes t a t the t ime of grading a t the Montca lm Resea rch

Farm. The da ta f rom 2000 to 2002 are s h o w n in Table 7. The

bru ise da ta are r ep r e s en t ed in two ways: pe rcen tage of bruise-

f ree po ta toes and average n u m b e r of bruises pe r tuber. Bruis-

ing levels of grea te r t h a n 1.5 b ru i ses pe r tube r and less t h a n

20°,6 bruise free are classif ied as very sensi t ive to bru is ing dur-

ing handling. The b l ackspo t bru ise reac t ion of At lant ic is clas-

sifted to be susceptible . Onaway had less b lackspo t bruis ing

t han Boulder and Atlantic was m o r e suscept ib le to b lackspo t

than Boulder. Each year an addi t ional sample of tubers t ha t

are no t pu t t h rough the s imula ted bru ise tes t ( check sample)

are also eva lua ted for b lackspo t bruising. The inc idence of

b lackspo t bru is ing in the check sample was low for Boulder

(Table 7).

Blind tes t tas tes are conduc ted by the b reed ing p rog ram

every year. Tubers of the tes t var ie t ies a re baked, s teamed, and

mic rowave baked. Boulder sco red above average in the tas te

tes ts (da ta no t shown) for baked, s teamed, and mic rowaved

2003 D O U C H E S e t al.: BOULDER 351

TABLE 7--Black-spot bruise results of "A "size tuber samples.

Yea~. 2000 2000 2001 2001 2002 Trial: MSU Chip/Table North Central MSU Chip/Table North Central MSU Chip/Table

Avg. Bruises %Tubers Avg. Bruises %Tubers Avg. Bruises %Tubers Avg. Bruises %Tubers Avg. Bruises %Tubers Per Tuber Bruise-free Per Tuber Bruise-free Per Tuber Bruise-free Per Tuber Braise-free Per Tuber Bruise-free

Entry: Check Samples 1 Boulder 0.3 27 0.1 12 0.1 8 0.2 16 Atlantic 0.7 48 0.3 19 0.2 20 0.1 12 Onaway 0.4 24 0.0 0

Simulated Bruise 2 Boulder 0.6 50 0.6 50 0.6 36 0.4 32 0.9 48 Atlantic 1.1 59 1.2 72 1.1 80 0.4 32 1.4 76 Onaway 0.6 42 0.4 28 0.2 12

1Tuber samples were collected at harvest, graded, and held until evaluation. Samples were abrasive-peeled and scored. ~uber samples were collected at harvest, held at 10 C at least 12 h, and placed in a six-sided plywood drum and rotated ten times to produce simulated bruising. Samples were abrasive-peeled and scored. Tuber samples consisted of a 25 tuber composite sample from four replications.

TABLE 8----Scab ( S t r e p t o m y c e s s c a b i e s ) disease reaction

from the Scab Nursery at the Michigan State

University Soils Farm, East Lansing, MI.

Entry 19981 1999 ~ 20002 20012 20022

Boulder 2.3 1.7 2.1 1.3 2.5 Atlantic 3.3 3.0 3.3 1.8 2.7 Onaway 1.5 1.2 1.2 0.9 1.7

LSD0 ~ 1.8 0.4 0.7 NS NS

~(1-5) Scab Disease Rating: 1: trace to practically no infection; 2: low infection; 3: average susceptibility; 4: high susceptibility; 5: severe susceptibility. 2(0-5) Scab Disease Rating: 0: no infection; 1: low infection <5%; 2: moderate susceptibility; 3: intermediate; 4: high susceptibility; 5: severe susceptibility. Mean comparisons were done using Fisher's Least Significant Difference (a = 0.05).

wi th var ie t ies such as Super ior and Russet B u r b a n k hav ing

average scores. The cooked whi t e f lesh of Boulder has a good

a p p e a r a n c e and the tas te is s m o o t h and pleasant .

DISEASE RESISTANCE

Replicated field trials were conduc ted at the MSU Soils

Fa rm Scab Nursery in Eas t Lansing, MI, to assess res i s t ance to

c o m m o n and pi t ted scab (Streptomyces scabies). Table 8 com-

pa res Boulder to Atlantic and Onaway. Based u p o n five years

of trials, Boulder has res i s t ance to scab tha t is g rea te r t h a n

Atlantic, bu t less than Onaway.

Boulder was also evaluated for foliar suscept ibi l i ty to late

bl ight (Phytophthora infestans de Bary) and the tube r s for

Erwinia sof t ro t (Erwinia carotova) and Fusarium sam-

bucinum (Fusarium dry rot) response . Al though res i s tance

was no t observed, the infect ion level was s imilar to o the r vari-

eties. Boulder does express PLRV and mosa ic symptoms, bu t

it has no t b e e n formal ly tes ted for its level of susceptibility.

Observa t ions dur ing field seed increase or during agronomic

trials did no t indica te any unusua l suscept ibi l i ty to PVX, PVY,

and PLRV. No Verticill ium (VerticiUium dah / i ae ) wil t infect ion

of Boulder was obse rved in 2001 in Minneso ta Verticillium wilt

field trials (C. Thill, pe r s comm).

ELECTROPHORETIC PATTERNS

Leaf and t u b e r t issue was sampled f rom Boulder to con-

s t ruc t a n e lec t rophore t ic fmgerprint . The p rocedure s and

allelic des igna t ions used are accord ing to Douches and Lud-

lam (1991). The t rat tscr ipt for t en enzyme loci is descr ibed as:

Mdh-1Z131414, Mdh-22222z2 z, 6-Pgdh-3132323 ~, Idh-

11111~12, Pgi-13p1212, Got-13PP1 s, Got-23232525, Pgm- 1 1 2 3 2 2 3 3 1 1 1 2 1 1 1 1, Pgm-2 2 '2 2 , Dia-1 1 1 1. This e lec t rophore t ic data

is ma in ta ined as pa r t of a da tabase wi th over 200 l ines and vari-

eties. The e lec t rophore t i c f ingerpr int is un ique to Boulder.

CHEMISTRY

Total t u b e r glycoalkaloids (TGA) were m e a s u r e d on

tubers col lec ted at ha rves t f rom 2000 to 2002. These samples

were sen t to e i ther Dr. Ken Deahl at the USDA/ARS/PSI Veg-

e table Labora tory or to Brian Perkins at the Universi ty of


TABLE 9--Total glycoalkaloids 1 (mg/l O0 g FW) from

fall-harvested tubers.

Entry 20002 20013 20023 Mean

Boulder 3.0 6.9 6.8 5.6 Atlantic 11.4 6.1 7.7 8.4

1Solid phase/ion pairing extraction (C18) HPLC/PDA detection. -'Maine - Brian Perkins. 3USDA-ARS - Kenneth Deahl

Maine Food Safety Laboratory for analysis. For these TGA

analyses the extraction and rapid high-performance liquid

chromatographic (HPLC) determination method was used

(Carman et al. 1986). Table 9 summarizes the TGA data for

Boulder along with Atlantic for 2000 to 2002. In each year the

level of TGA was well within the acceptable range (below 20

mg TGA/100g fresh weight) for Boulder and Atlantic.

ACKNOWLEDGMENTS

The development and testing of Boulder was supported in

part by the Michigan Agricultural Experiment Station, Michi-

gan Potato Industry Commission, NCR-84 Potato Breeding and

Genetics Technical Committee, and the USDA Special Grant

for Potato Breeding/Variety Development. Lynn Frank, Kim

Felcher, and Jarred Driscoll provided technical support.

LITERATURE CITED

CmTnan AS, SS Shia, GM Ware, OJ Francis, and GP Kirschenheuter. 1986. Rapid high-performance liquid chromatographic determination of the potato glycoalkaloids (x-solanine and a-chaconine. J Agric Food Chem 34:279-282.

Douches DS, and K Ludlam. 1991. Electrophoretic characterization of North American potato varieties. Am Potato J 68:767-780.

SEED AVAILABILITY

Virus-free tissue culture plantlets of Boulder were sent to

Sklarczyk Seed Farm (8714 M32 East, Johannesburg, M149751,

phone 989-731-5452) and Krueger Seed Farm (2797 W. Hawkes

Hwy., Hawks, MI 49743, phone 989-734-7366). Small amounts

of seed for testing can be obtained from Dave Douches at

Michigan State University (517-355-6887, [email protected]).

Plant Variety Protection for Boulder is in application stage.

Documents

Boulder: A round white multipurpose potato variety