assessment of genetic diversity in potato germplasm

Crop Improv. 33(1):78-8(2006)

ASSESSMENT OF GENETIC DIVERSITY IN POTATO GERMPLASM FOR SPRING SEASON CROP 1

S K SANDHU1* AND J GOPAL2 Central Potato Research Station, Jalandhar - 144 003 (Punjab) 2 Central Potato Research Institute, Shimla - 171 001 (HP)

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ABSTRACT One hundred ninety three germplasm accessions of potato (Solanum tuberosum ssp. tuberosum) germplasm, from eight countries, were evaluated for nine characters under long day (14-15 hrs) and high temperature (max.19.0-40°C and min. 7.0-25°C) conditions of spring crop. Experiment was laid out in a augmented incomplete block design with four potato varieties as checks. Significant variability was observed for majority of the characters among checks as well as test genotypes. Non-hierarchical Euclidean cluster analysis followed by principal component analysis led to the classification of 193 accessions into nine wellcharacterized groups. The maximum Euclidean distance was between cluster V and VIII followed by ill and VIII. The cluster VIII was deemed good for selecting elite accessions as the genotypes gathered in this cluster were not only diverse from each other but also had the highest mean values for plant height (57.5 cm), inter-node length (3.42 cm), number of leaves/plant (112), average tuber weight (27.3 g) and tuber yield per plant (380 g). Six accessions, viz., CP1367,1438,1513,1551,1558 and 1588 were identified as genetically diverse and agronomically superior and thus recommended for exploitation in potato breeding programme for spring season. Index Words :

Solanum tubersum, genetic divergence, cluster analysis, intra and inter cluster distances

Potato is the fourth most i m p o r t a n t food crop in India as well as in w o r l d after w h e a t , rice and maize. In the plains of India, potato is mainly grown d u r i n g a u t u m n from O c t o b e r t o J a n u a r y u n d e r short day conditions. However, a s e c o n d crop is also grown during s p r i n g s e a s o n e x c l u s i v e l y for w a r e p o t a t o e s , f r o m J a n u a r y t o May, t h e a r e a under this c r o p is m u c h less in c o m p a r i s o n to autumn. This is mainly d u e to non-availability of high yielding potato v a r i e t i e s for s p r i n g s e a s o n . The present investigation w a s a i m e d at identifying potato germplasm under spring conditions. Genetic divergence based on m o r p h o l o g i c a l characters can be u s e d as an i n d i r e c t p a r a m e t e r of m o d e r a t e effectiveness in selecting parents to produce

heterotic high y e i d l i n g p r o g e n i e s , if parents are evaluated under c o n d i t i o n s in which crosses are likely to be e v a l u a t e d (Gopal and Minocha, 1997). K e e p i n g this in view, 193 a c c e s s i o n s of potato g e r m p l a s m were e v a l u a t e d in spring season and c h a r a c t e r i z e d into genetically diverse groups. MATERIAL AND METHODS The mateial c o m p r i s e d of 193 potato germplasm (Solanum

tuberosum

spp.

tuberosum)

accessions

(clones/varieties/cultivars) along with four check cultivars viz., Kufri C h a n d r a m u k h i , Kufri Sutlej, Kufri Jyoti and Kufri B a d s h a h . Each accessions was planted in a single 2 . 4 m long row with intra

"Present address: Departmant of Plant Breeding, Genetics & Biotechnology, PAU, Ludhiana




June, 2006]

Genetic Diversity in Potato

and inter row s p a c i n g of 2 0 c m a n d 60 c m , respectively. The r e c o m m e n d e d package of practices were followed. Data were recorded for nine c h a r a c t e r s viz., t u b e r y i e l d / p l a n t , a v e r a g e t u b e r w e i g h t , t u b e r n u m b e r / p l a n t , plant h e i g h t , number of n o d e s , i n t e r - n o d e l e n g t h , n u m b e r of stems, number of leaves and leaf let index. Foliage c h a r a c t e r s w e r e r e c o r d e d on 85 d a y s of c r o p m a t u r i t y on five c o m p e t i t i v e p l a n t s of e a c h genotype and tuber traits at 90 days of harvest on plot basis. Data were statistically a n a l y z e d to find adjusted mean values (Federer and Raghavarao, 1 9 7 5 ) w h i c h i n t u r n w e r e u s e d for p r i n c i p a l component analysis to transform the inter d e p e n d e n t v a r i a b l e s into a set of i n d e p e n d e n t variables (Mardia, 1971; Hottling, 1933). The principal conponent s c o r e s were used to c o m p u t e Euclidean d i s t a n c e s b a s e d o n n o n - h i e r a r c h i c a l cluster analysis (Beale, 1969; Spark, 1973) statistical software SPARI. A n a l y s i s was based on mean data of two years. RESULTS A N D DISCUSSION The analysis of variance (Table 1) showed that the block effects were in general non-significant for all the characters, w h e r e a s t r e a t m e n t effects were

79

s i g n i f i c a n t for m a j o r i t y of t h e c h a r a c t e r s . Test accessions differed for all the characters except for leaflet index and tuber number per plant. There was c o n s i d e r a b l e genetic differences b e t w e e n check varieties. Range, mean and coefficient of variation c h a r a c t e r s are g i v e n in Table 2. T h e m a x i m u m variation was for number of leaves per plant (59.18%) followed by number of stems (53.125%) and tuber number per plant (52.80). The coefficient of variation for average tuber weight, plant height and tuber yield per plant was 49.4, 47.2 and 42.5%, respectively. Moderate coefficient of variability were obtained for number of nodes and internode length whereas it was t h e l o w e s t for l e a f l e t i n d e x . T h e p r e s e n c e o f considerable variability among the accessions for various c h a r a c t e r s i n d i c a t e d the wide scope for utilization of these a c c e s s i o n s in improvement of potato. Non-hierarchical Euclidean cluster analysis followed by principal c o m p o n e n t analysis, led to the classification of 193 a c c e s s i o n s into nine well characterized groups with 20 genotypes in cluster I, 27 in cluster II, 16 in III, 25 in IV, 32 in V, 18 in VI, 41 in VII, five in VIII and nine in cluster IX (Table 3). The intra-cluster d i s t a n c e ranged from (2.107). M a x i m u m inter-cluster distance was between V and

Table 1. Mean sum of squares for various characters in potato.

Blocks Treatments

d.f.

Plant height

No. of nodes

4

52.61

8.11

Internode length

No. of stems

No. of leaves

0.17

0.19

290

Leaflet index

Tuber yield/ plant

Tuber number/ plant

Average tuber weight

0.02

1425

44.18

3.82

0.06

10367

78

51.86

0.22**

10252

156*

34.97

196

271"

20.09*

0.36**

5.93*

876*

3

295"

10.4

0.34*

4.58

962"

Test accessions

192

212"

17.27*

0.32*

5.65*

656*

0.06

8122**

Check varieties Vs. test accessions

1

11496"

8.15**

63.03"

42644"

0.02

164992

2.04

266.89

0.03

1384.59

Check varieties

Error

12

42.25

591**

6.11

0.10

73.7 622

450.77

52.37" 4.64

13.07

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S.K. Sandhu, J. Gopal

[Vol.33 No.1




Table 2. Mean, range and coefficient of variation for various characters in potato Coefficient of variation (cv) %

Range

Characters

Mean

Tuber yield/plant (g)

211.72

33.0

Average tuber weight (g)

17.38

5.0

46.80

49.4

Tuber number/plant

13.71

4.40

58.4

52.8

Plant height (cm)

30.83

10.50

82.0

47.2

No. of nodes

12.57

5.0

26.0

33.0

492.0

4.26

42.5

23.5

Inter-node length (cm)

2.41

1.25

No. of stems

4.46

1.00

20.5

53.1

No. of leaves

43.29

5.00

155.60

59.2

Leaflet index

1.51

1.03

2.915

15.9

Table 3. Distribution of 193 potato accessions into different clusters Cluster

No. of

Accessions number (CP No.)

I

20

1123, 1151, 1172, 1205, 1235, 1239, 1243, 1382, 1385, 1399, 1400, 1404, 1408, 1440, 1455, 1518, 1544, 1545, 1547 and 1586

II

27

659, 1162, 1178, 1180, 1218, 1231, 1235, 1302, 1304, 1310, 1314, 1340, 1344, 1345, 1348, 1350, 1365, 1366, 1368, 1383, 1390, 1453, 1490, 1519, 1574, 1593 and 1602

III

16

721, 1143, 1213, 1378, 1380, 1408, 1475, 1476, 1524, 1576, 1582, 1591, 1595, 1597, 1598 and 1607

IV

25

1163, 12.7, 1339, 1352, 1395, 1401, 1402, 1418, 1420, 1457, 1466, 1472, 1473, 1474, 1482, 1483, 1485, 1486, 1497, 1513, 1546, 1558, 1564, 1566 and 1608

V

32

658, 1057, 1086, 1160, 1187, 1232, 1237, 1246, 1275, 1308, 1316, 1317, 1319, 1330, 1342, 1343, 1345, 1361, 1386, 1407, 1412, 1415, 1426, 1427, 1433, 1435, 1436, 1467, 1548 and 1612

VI

18

1215, 1338, 1355, 1373, 1428, 1441, 1451, 1463, 1477, 1480, 1527, 1529, 1539, 1563, 1589, 1592, 1596 and 1611

VII

41

1181, 1225, 1233, 1242, 1346, 1351, 1374, 1375, 1391, 1392, 1398, 1414, 1417, 1421, 1424, 1425, 1429, 1432, 1443, 1444, 1445, 1448, 1449, 1456, 1460, 1461, 1462, 1465, 1479, 1487, 1491, 1503, 1507, 1516, 1523, 1571, 1590, 1594, 1604, 1615 and 1616

VIII

5

1367, 1439, 1442, 1555 and 1588

IX

9

655, 1175, 1353, 1358, 1362, 1431, 1515, 1530 and 1538

June, 2006]

Genetic Diversity in Potato




VIII (7.771) followed by III and VII (&.734) (Table 4). Inter and intra cluster distances, which provided index of genetic diversity a m o n g and within the clusters respectively, revealed that i n t r a - c l u s t e r distances were of lower m a g n i t u d e as c o m p a r e d to inter-cluster d i s t a n c e s . It s u g g e s t e d that g e n o t y p e s of s a m e c l u s t e r had little d i v e r g e n c e from each other. Therefore, hybridization a m o n g t h e a c c e s s i o n s o f s a m e c l u s t e r w o u l d not b e desirable. The a c c e s s i o n s c o l l e c t e d from one region were scattered in all the clusters suggesting thereby that there is no parallelism between genetic and geographical diversity. T h e s e findings are in agreement with earlier studies (Gaur et al. 1978; Gopal, 1999). Cluster-wise mean values for important traits are given in Table 5. The cluster VIII was d e e m e d good for selecting elite a c c e s s i o n s as t h e g e n o t y p e s gathered in this cluster was not only diverse from others (as revealed by highest intercluster value) but also had the h i g h e s t m e a n v a l u e s for yield contributing traits, viz., plant height (57.5cm), internodal length (3.42cm), number of leaves/plant

Table 4.

Cluster number 1 2 3 4 5 6 7 8 9

81

(112), average tuber weight (27.3 g) and tuber yield per plant (380 g). The use of genetic distances b e t w e e n p a r e n t s in p r e d i c t i n g p r o g e n y m e a n s , heterosis and specific c o m b i n i n g ability for tuber y i e l d in p o t a t o is well d o c u m e n t e d ( G o p a l and Minocha, 1997). Exploiting the genotypes falling in this cluster in breeding programme is expected to give segregates with high genetic yield potential. Besides clustering of genotypes, promising accessions for tuber yield and its components were identified (Table 6). Five accessions, viz., CP 1215, 1442, 1557, 1563 a n d 1589 had average tuber number > 30. Such a c c e s s i o n s could be exploited for p r o d u c i n g baby p o t a t o e s and c a n n i n g . The tuber development in potato under spring conditions is a major problem as the temperature for tuber bulking prevails only for a short duration. Four a c c e s s i o n s , CP 1420, 1466, 1513 and 1546 with average tuber weight > 40g were considered a d a p t e d to spring s e a s o n for early tuberization. Genotypes with delayed tuberization are not fit for spring crop as this leads to preferential utilization of p h o t o s y n t h a t e s towards addition of foliage than

Estimates of average intra- and inter-cluster distances based on nonhierarchical Euclidean cluster analysis of 193 accessions of potato germplasm 1

2

3

4

5

6

7

8

9

2.203

2.469

2.650

3.770

2.256

3.723

2.280

7.195

5.954

1.193

2.684

2.907

2.118

2.939

3.984

6.258

5.096

1.464

2.760

2.107

4.338

2.373

7.734

6.189

1.962

3.974

3.438

2.514

5.676

4.434

1.594

3.994

2.221

7.771

6.215

2.265

2.653

4.391

4.275

1.610

6.239

4.764

2.023

4.764 2.340

Diagonal (bold face) values indicate average intracluster distances and under lines values indicate the highest (7.771) and the lowest (2.107) intercluster distances

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S.K. Sandhu, J. Gopal




Table 5. Performance of different clusters for yield contributing characters Plant height (cm)

No. of stems

No. of leaves

Tuber yield/ plant (g)

Tuber number/ plant

Average tuber weight (g)

I

19.04

4.66

27.36

178.50

12.69

14.57

II

29.18

4.23

32.75

191.76

13.19

15.73

III

19.36

2.90

26.63

190.22

26.54

7.33

IV

36.00

4.62

49.01

322.16

31.46

10.87

V

20.38

3.19

24.22

113.24

10.66

10.93

VI

34.84

6.45

68.99

289.64

11.27

25.81

VII

33.18

3.89

44.60

201.40

16.66

12.36

VIII

57.46

13.50

111.78

380.20

18.56

27.30

IX

42.17

8.50

40.62

223.27

13.50

17.03

Table 6. Promising accessions identified for different characters from potato germplasm Tuber yield/plant (g)

CP 1367 (400), CP 1438 (462), CP 1513 (332), CP 1551 (481), CP 1558 (398) and CP 1588 (384) Kufri Jyoti was 332, CD (0.05) 34.9 and CV 9.4%

Tuber weight (g)

CP 1420 (41.70), CP 1466 (43.80), CP 1513 (38.40) and CP 1546 (43.50) Kufri Jyoti was 27.8; CD (0.05) 10.9 and CV 6.4%.

Tuber number

CP 1215 (32.4), CP 1442 (33.20), CP 1557 (37.4), CP 1563 (31.2) and CP 1589 (34.6) Kufri Jyoti was 12; CD (0.05) 13.8 and CV 8.9%.

tubers due to non-availability of sink (Mehta et al. 1988). Since in potato, t u b e r yield is one of the most important traits, six elite g e n o t y p e s , viz. CP 1367, 1438, 1513, 1 5 5 1 , 1 5 5 8 a n d 1 5 5 8 w e r e i d e n t i f i e d from g e r m p l a s m s t o c k w h i c h y i e l d e d significantly higher t h a n the best c h e c k cultivar Kufri J y o t i (Table 5 ) . T h e s e a c c e s s i o n s w e r e grouped in diverse clusters (CP 1513 and CP 1558 in cluster IV and CP 1367, CP 1438, CP 1551 and CP 1588 in cluster VIII) and were horticulturally superior with acceptable tuber a p p e a r a n c e . T h e s e accessions can be a d v a n t a g e o u s l y used in breeding programmes aimed to breed varieties suitable for spring season. The evaluation of potato

g e r m p l a s m led to the identification of promising and p h e n o t y p i c a l l y diverse genotypes for spring season. T h e s e may serve as potential parents for exploitation in further breeding programme.

ACKNOWLEDGEMENT Assistance provided by Mr. G u r n a m Das, Technical Assistant-TII and Mr. Raj Kumar Technical Officer (statistics),

CPRS,

Jalanahar

is

gratefully

acknowledged.

REFERENCES Beale, E.M.L.H. (1969). Euclidean cluster analysis. Contributed paper to the 37th Session of the International Statistical Institute, U.K.

June, 2006]

Genetic Diversityin

Federer, W.T. and R a g h a v a r a o , D. (1975). On augmented designs. Biometrics 31: 191-208. Gaur, P.C., Gupta, P.K. and Kishore, H. (1978). Studies on genetic divergence in potato. Euphytica 27: 36168.

Gopal, J. (1999). In vitro versus in vivo genetic divergence in potato. Theor. Appl. Genet. 98: 299304. Gopal, J. and Minocha, J.L. (1997). Genetic divergence for cross prediction in potato. Euphytica 97: 269275.




Hottling, H. (1933). Analysis of a complex of statistical variables into principal components. Mordia Educational Psychology 24: 417-41.

Potato

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Marida, K.V. (1971). The effect of non-normality on some multivariate tests and robustness to non-normality in the linear model. Biometrika 58: 105-121. Mehta, A., Banerjee, V.N. and Kaley, D.M. (1988). Vegetative development of potato grown in autumn and spring in Punjab. Indian J. Plant Physiol. 31: 145-51. Sharma, B.D., Kaul, H.N. and Mukhtar Singh (1982). Growth analysis of potato varieties in spring plains. In: Potato in developing countries. Eds. Nagaich, B.B. Shekhawat, G.S., Gaur, P.C. and Verma, S.C. Indian Potato Assoc CPRI, Shimla, pp. 253-64. Spark, D.N. ( 1 9 7 3 ) . E u c l i d e a n cluster analysis. Algorithm Appl. Stat. 22: 126-30.