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N.S. Debremismak mariam. 2840. 103 FBColl-166/99 ... N.S. Gebelwash mariam. 2980 ..... Katule B.K., Thombare M.V., Dumbre A.D. and Pawar B.B.. 1992.
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Genetic Resources and Crop Evolution (2005) 52: 551–561 DOI 10.1007/s10722-003-6022-8

Extent and pattern of genetic diversity for morpho-agronomic traits in Ethiopian highland pulse landraces II. Faba bean (Vicia faba L.) Gemechu Keneni1,*, Mussa Jarso1, Tezera Wolabu2 and Getnet Dino1 1

Holetta Agricultural Research Center, P. O. Box 2003, Addis Ababa, Ethiopia; 2Kulumsa Agricultural Research Center, P.O. Box 489, Asella, Ethiopia; *Author for correspondence

Received 26 August 2002; accepted in revised form 19 September 2003

Key words: Cluster and distance analyses, Faba bean, Genetic diversity, Geographic origin, Germplasm, Landrace, Vicia faba

Abstract A field experiment was conducted in 2001 at Holetta and Kulumsa, Ethiopia, to study genetic diversity in Ethiopian faba bean (Vicia faba L.) landraces. One hundred sixty random germplasm accessions were grown in an alpha lattice design with two replications. Data on 12 traits were collected and analyzed. Significant differences were observed among the accessions for most of the traits (except number of pods/podding nodes) at each location even though differences pooled over location were mostly non-significant. Cluster analysis distinguished seven diversity classes of different sizes. Accessions from the northern half of the country (North and South Wello, North Gonder and North Shewa) were closely related while those from the southern part of the country (Arsi) were highly diverse. Cumulative effects of a number of characters dictated differentiation of the accessions into clusters. Some overlapping were encountered between accessions from the northern and those from the southern parts of the country. The study revealed that accessions from different regions might have similar genetic background and those from the same origin might also have different genetic background. Therefore, geographic diversity should not necessarily be used as an index of genetic diversity and parental selection should be based on a systematic study of genetic diversity in a specific population. Genetic distances between most of the clusters were significant that crosses between parents selected out of them are expected to generate desirable progenies. Future germplasm collection, conservation and utilization strategies should put more focus not only on inter-regional diversity in the country as a whole but also on intra-regional diversity in Arsi.

Introduction Information on genetic diversity in a germplasm is essential for parental selection in hybridization (Bartual et al. 1985; Dale et al. 1985; Jaradat 1991), and for planning efficient germplasm collection, conservation and utilization (Rezai and Frey 1990; Demissie and Bjørnstad 1997). Crosses between groups with maximum genetic divergence

would be more responsive to improvement since they are likely to produce higher heterosis (Arunachalam and Bandyopadhyay 1984; Singh 1990) and desirable genetic recombination and segregation in their progenies (Reddy 1988; Singh 1990; Chahal and Gosal 2002). There are also reports indicating that parents of intermediate genetic divergence might show more heterosis and genetic recombination and segregation

552 (Arunachalam et al. 1984). Crosses between parents with high inter-parental diversity may also help to develop varieties with broad genetic base (Russell 1978; Singh 1990; Gemechu et al. 1997). Landraces have considerable breeding values as they contain co-adapted gene complexes with tolerance or adaptation to diseases and specific ecological conditions (Harlan 1975). They are also useful in breeding for marginal areas (Nechit et al. 1988; Ceccarelli 1994; Bunder et al. 1996) as they offer genes responsible for a more stable yield over a wide range of environmental conditions (Hawkes 1983; Chahal and Gosal 2002). A large number of faba bean landraces have been collected from the most important production complexes in Ethiopia (Dawit et al. 1994). However, information on the extent and pattern of genetic diversity in these landraces is not systematically studied (Hailu et al. 1991). Some investigators claimed that Ethiopian germplasm are dominated with the small-seeded (var. minor) types all over the country (Westphal 1974; Engels and Hawkes 1991) but others consider the country to be the secondary center of diversity (Bond 1976; Singh 1990; Hailu et al. 1991) with both the small-seeded (var. minor) and the mediumseeded (var. equina) types (Amare 1990; Asfaw et al. 1994). Some believe that the medium-seeded and the small-seeded types dominate in the northern and the southern parts of the country, respectively (Asfaw et al. 1994), while others believe the opposite to be true (Amare 1990). The reports, however, do not emanate from scientific evidence based on a systematic study apart from some informal observations (Hailu et al. 1991). Genetic diversity arises either due to geographical separation or due to genetic barriers to crossability (Singh 1990). Whether differences in geographic origin (source) imply genetic distance in parental selection for hybridization is still a matter of some controversy. Joshi and Dhawan (1966) suggested the concept that geographic diversity may serve as an index of genetic diversity in parental selection. Others argue that genetic divergence was not apparently related to geographic diversity in some crops (Durga Prasad et al. 1985; Sindhu 1985; Nadaf et al. 1986; Rezai and Frey 1990; Katule et al. 1992). As Ethiopia is a country of great geographical diversity with high and rugged mountains (EMA 1988), it is logical to expect that the physical barriers might have resulted in distinct genetic diver-

sity of faba bean germplasm growing in different parts of the country. The objectives of this experiment were, therefore, to estimate the extent and pattern of genetic diversity among the Ethiopian faba bean landraces, the relative contribution of various morpho-agronomic traits to the total diversity in the germplasm and to study the association of geographic origin with genetic diversity.

Materials and methods One hundred sixty accessions of faba bean germplasm collected in collaboration with the Institute of Biodiversity Conservation and Research from the most important production complexes of Ethiopia were studied. The list of the test accessions is given along with their geographical origins in Table 1. Areas covered during the collection Table 1. Origin of accessions. SN1

Accession

Zone2

Locality

Altitude (m asl)

1 2 3 4 5 6 7

FBColl-1/99 FBColl-2/99 FBColl-3/99 FBColl-4/99 FBColl-5/99 FBColl-6/99 FBColl-7/99

N.W. N.W. N.W. N.W. N.W. N.W. N.W.

2790 2790 2790 2800 2790 2820 2840

8

FBColl-8/99

N.W.

9 10 11

FBColl-9/99 FBColl- 10/99 FBColl- 11/99

N.W. N.W. N.W.

12

FBColl- 12/99

N.W.

13

FBColl- 13/99

N.W.

Betehor Betehor Betehor Yewetet Yewetet Kon Yedogit Michael Woteye Giorgis Yekorit Terara Woteye Giorgis Gurba Giorgis Mushmender

14 15 16 17 18 19

FBCollFBCollFBCollFBCollFBCollFBColl-

N.W. N.W. N.W. N.W. N.W. N.W.

20 21 22 23 24 25

FBColl-20/99 FBColl-21/99 FBColl-22/99 FBColl-23/99 FBColl-24/99 FBColl-25/99

14/99 15/99 16/99 17/99 18/99 19/99

S.W. S.W. S.W. S.W. S.W. S.W.

Chegoma Chinga Yilana Boda Goshmeda Goshmeda Giorgis Gishen Gewot Kundi Ababoru Grume Tenta

2400 2350 2460 2590 2700 Treshing ground 2820 2850 2900 2960 2490 Farm Store Farm Store 2400 Farm Store Market 2870 2780

553 Table 1. (Continued).

Table 1. (Continued).

SN1

Accession

Zone2

Locality

Altitude (m asl)

26 27 28 29

FBColl-26/99 FBColl-27/99 FBColl-28/99 FBColl-29/99

S.W. S.W. S.W. S.W.

Gendit Tenta Debir Godo (Chacha) Taba

30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81

FBColl-58/99 FBColl-59/99 FBColl-60/99 FBColl-61/99 FBColl-62/99 FBColl-63/99 FBColl-64/99 FBColl-65/99 FBColl-66/99 FBColl-67/99 FBColl-68/99 FBColl-69/99 FBColl-70/99 FBColl-71/99 FBColl-72/99 FBColl-73/99 FBColl-74/99 FBColl-75/99 FBColl-76/99 FBColl-77/99 FBColl-78/99 FBColl-79/99 FBColl-80/99 FBColl-81/99 FBColl-82/99 FBColl-83/99 FBColl-84/99 FBColl-85/99 FBColl-86/99 FBColl-87/99 FBColl-88/99 FBColl-89/99 FBColl-90/99 FBColl-91/99 FBColl-92/99 FBColl-93/99 FBColl-94/99 FBColl-95/99 FBColl-96/99 FBColl-97/99 FBColl- 133/99 FBColl- 134/99 FBColl- 135/99 FBColl- 136/99 FBColl- 137/99 FBColl- 138/99 FBColl- 139/99 FBColl- 140/99 FBColl- 141/99 FBColl- 142/99 FBColl- 143/99 FBColl- 144/99

N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.G. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

Gonder Zuria Gonder Zuria Degoma Awdeba Gind Metaya Tafta Sheloke Shembel Kit Magiber Ambezu Ambezu Koseye Wondgate Amba Giorgis Hiywet badema Telba minch Workdemo Gedebeye Chemelgie Deldalit Shimelako Kuara Tentanie Wuramba Dildiye Tawra Kumbel Miljgebsa Aman amba Afaf Limalimo afaf Mariam Debir Mikara Arba Tensa Dequa Abay Chenchit Birkach Selamgie Selamgie Woken Zanjera Kinbo Ager Arathside Keyit Aba mute Liymush Gudo Beret Ezawienel Bilbena Ezawienel Bilbena Kuromider Tiftef Dingay Bash

2780 2780 2630 Treshing ground 2500 2500 2500 2200 2300 2240 2400 2540 2660 2660 2800 2900 2840 2700 2660 2680 2700 2640 2560 2580 2600 2680 2660 2800 2700 2960 3000 3100 2700 2700 2700 2720 2660 2600 2500 2540 2500 2300 2300 2620 2740 2800 2800 2840 2900 2900 2960 2940 2940 2780 2890 2820

82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140

FBColl- 145/99 FBColl-146/99 FBColl-147/99 FBColl-148/99 FBColl-149/99 FBColl-150/99 FBColl-151/99 FBColl-152/99 FBColl-153/99 FBColl-154/99 FBColl-155/99 FBColl-156/99 FBColl-157/99 FBColl-158/99 FBColl-159/99 FBColl-160/99 FBColl-161/99 FBColl-162/99 FBColl-163/99 FBColl-164/99 FBColl-165/99 FBColl-166/99 FBColl-167/99 FBColl-168/99 FBColl-169/99 FBColl-170/99 FBColl-171/99 FBColl-172/99 FBColl-173/99 FBColl-157/00 FBColl-159/00 FBColl-161/00 FBColl-163/00 FBColl-164/00 FBColl-168/00 FBColl-170/00 FBColl-172/00 FBColl-176/00 FBColl-178/00 FBColl-181/00 FBColl-184/00 FBColl-187/00 FBColl-188/00 FBColl-191/00 FBColl-193/00 FBColl-196/00 FBColl-199/00 FBColl-201/99 FBColl-204/00 FBColl-205/00 FBColl-208/00 FBColl-209/00 FBColl-211/00 FBColl-214/00 FBColl-217/00 FBColl-220/00 FBColl-222/00 FBColl-224/00 FBColl-226/00

N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi

Weynber Angewa Angewa Molale Emego/Arbadifo Emego Dega Shenkor meda Gedembo Sinaamba Chiroche amba Menta debir Sarmider Anamariam Zemro Negassi amba Geragne medhanialem Amashna GacheAmba Begoch Gat Necho Ager Aliyu Amba Debremismak mariam Sela dingay Gebelwash mariam Gudu beret Hausini amba Wushu wishi Debel Adgo ager Kura mariam Burkitu Temensa gngesa Digelu bora Digelu bora Gusha Debelencha Lemueddo (Samuna) Hella Zenbaba Gobessa town Beritti faricho Sirbo Shashe Eje gora Shire Aragesa Shire Aragesa Goljote Damudimbiba Tullu jebbi Esalode Hada wayu Jegna barbuko Jegna barbuko Sedika burka Aman Lema Meraro sibbe Kako (Dange) Sibbe meraro Darole Bele town Walansho Jidda jiru

2840 2820 2820 2820 2920 2960 3140 3100 2940 2900 2880 2860 2840 2860 3000 3000 3000 2940 2940 2900 2840 Market 2980 3000 2750 2800 2940 3080 3160 2550 2500 2680 2680 2450 2740 2360 2380 2950 2780 2940 2740 2850 2840 2000 2200 2520 2680 2560 2380 2360 2370 2350 2400 2410 2390 2420 2400 2420 2440

554 Table 1. (Continued). 1

2

SN

Accession

Zone

Locality

Altitude (m asl)

141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160

FBColl-228/00 FBColl-231/00 FBColl-233/00 FBColl-236/00 FBColl-238/00 FBColl-240/00 FBColl-242/00 FBColl-244/00 FBColl-246/00 FBColl-248/00 FBColl-250/00 FBColl-252/00 FBColl-255/00 FBColl-257/00 FBColl-259/00 FBColl-261/00 FBColl-263/00 FBColl-265/00 FBColl-267/00 FBColl-269/00

Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi Arsi

Chefe Ticho town Ticho town Brhala town Brhala town Hella Andode Sude alegito Alendo Hursa Sire town Sire town Borora chire Rei amba Nano hecho Near Moye town Kore waryam Akiya Tullu Eba Bilashulli Warabu jawi Abomsa town

2340 2500 2500 2570 2570 2530 2500 2440 2000 1970 1970 2460 2660 2760 2970 2840 2680 2620 2520 1750

1

SN=Serial Number. N.W=North Wello, S.W.=South Wello, N.G.=North Gonder and N.S.=North Shewa. 2

mission, description of the testing locations, the design used in the study, the field management and models and procedures of analyses used are given in Part I of this paper. Each plot consisted of two rows 4 m long with a spacing of 40 cm between rows and 5 cm between plants. Data were collected either on plot basis or from randomly selected ten plants on:

1. Days to flowering 2. Days to maturity 3. Grain filling period (days to maturity minus days to flowering) 4. Plant height (cm) 5. Chocolate spot (Botrytis fabae L.) (1–9 scale) 6. Number of nodes/plant 7. Number of podding nodes/plant 8. Number of pods/podding nodes 9. Number of pods/plant 10. Number of seeds/pod 11. 1000 seed weight (g) 12. Grain yield/plot (g)

Results and discussion There were highly significant differences among the accessions for most of the traits at both locations, except for number of pods/podding nodes, indicating the presence of adequate variability among the accessions and the possibility to undertake cluster and distance analysis. Pooled differences among the accessions were mostly nonsignificant (Table 2). Cluster analysis of accessions distinguished seven diversity classes of different sizes (Table 3 and Figure 1), different members within a cluster being assumed to be more closely related in terms of the traits under consideration with each other than those members in different clusters. Similarly, members in clusters with non-significant distance were assumed to have more close relationships

Table 2. Mean square, significance and CV% of morpho-agronomic characters and disease score of faba bean accessions. Trait

Days to flowering Days to maturity Grain filling period Plant height Chocolate spot Number of nodes/plant No. of podding nodes/plant No. of pods/podding nodes No. of pods/Plant No. of seeds/pod 1000 seed weight (g) Grain yield/plot (g)

Mean square (CV%) Holetta

Kulumsa

Combined

27.72** (2.88) 8.07** (1.36) 21.27** (2.86) 374.88** (8.62) 0.94** (11.64) 6.96** (7.09) 2.54* (24.87) 0.37NS (53.59) 5.90** (27.36) 0.20NS (13.35) 12533.54** (9.38) 11869.38** (33.84)

16.70** (4.15) 1.81* (0.93). 16.22** (3.67) 148.10** (7.44) 0.73** (30.75) 37.56NS(17.22) 4.25** (22.58) 0.18NS(30.74) 9.72** (27.54) 0.30** 6934.64** (17.28) 10425.57** (11.14)

5.04** (3.57) 2.95NS(1.21) 5.40NS(3.20) 90.18NS(8.69) 0.38NS(14.43) 21.62NS(16.02) 2.47NS(24.88) 0.26NS(44.05) 5.73NS(29.59) 0.20NS(15.61) 1663.76* (10.15) 4012.25** (32.58)

NS, *, **Indicates non-significant, significant and highly significant differences, respectively.

555 Table 3. Grouping of 160 faba bean accessions into different diversity classes. Cluster

Number of accessions

Accessions included (SN)

Origin

C1

94

[4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] [20,21,22,24,25,26,27,28,29] [30,36,37,38,40,41,43,45,46,47,50,51,52,53,54,55,56,57,58,59,60, 61,62,63,64,65,67,68] 70,71,72,73,74,75,76,77,79,80,81,82,83,84,85,86,87,88,89,91,93, 94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110] [155,156,157] [1,2,3] [23] [31,32,33,34,35,39,42,44,48,49,66,69] [78, 90, 92] [119,123,124,128,143,144,145,146,151,152,153,154,158,160] [112,113,114,115,116,118,120,122,159] [117,125,129,132,133,134,135,136,137,138,139,140,141,142,147,148] [121,126,127] [111,149,150] [130,131]

North Wello South Wello North Gonder

C2

33

C3 C4 C5 C6 C7

9 16 3 3 2

North Shewa Arsi North Wello South Wello North Gonder North Shewa Arsi Arsi Arsi Arsi Arsi Arsi

SN = Serial Number.

with each other than they are with those in significantly distant clusters. Cluster C1 was the largest with 94 accessions followed by cluster C2 with 33 accessions. Clusters C3 and C4 had 9 and 16 accessions, respectively. Clusters C5 and C6 had three accessions each while cluster C7 had two accessions. Out of 21 possible pairs of clusters, differences between 16 pairs were highly significant (P < 0.01) while those between the rest of the clusters were non-significant (Table 4). The maximum distance was found between clusters C1 and C7 (D2 = 152). Cluster C1 constituted accessions from all regions while cluster C7 constituted only those from Arsi. The second most divergent clusters were cluster C5 and C7 (D2 = 140), both with accessions collected from Arsi. Genetic distances between all other clusters were also highly significant (P < 0.01) except clusters C1 with C2, C1 with C5, C2 with C4, C2 with C5 and C4 with C6. Maximum segregation and genetic recombination is expected from crosses that involve parents from the clusters characterized by significant distances. It is assumed that accessions in clusters with non-significant distances are closely related among themselves. Like field pea, the results revealed that genetic diversity in this species is not uniformly distributed between the southern (Arsi) and northern (North Gonder, North Shewa and South Wello)

halves of the country. It seems that accessions from North and South Wello, North Gonder and North Shewa were closely related regardless of their geographic origin (source) and the rugged nature of the terrain which could have favored isolation among the accessions and, hence, distinct lines of evolution in each region. Accessions from this part of the country fell into clusters C1 and C2, which were non-significantly distant from one another (Table 5). This indicates that accessions from different regions might have similar genetic background due to several possible reasons. Most of the materials in this part of the country might have originally been introduced from the same source, followed by frequent exchange of seeds among farmers in these proximal regions of the country. There could also be a tendency, particularly among resource-poor farmers in marginal areas, of selecting for the same traits of interest like yield stability, resistance to diseases, insects and abiotic calamities and low dependence on the external inputs (de Boef et al. 1996). Although the original sources might vary, the crop might have also been forced to evolve in the same direction by this kind of local breeding for the same targets which may emanate from similar economic, social, cultural and ecological reasons in the area. Unlike in the northern parts of the country, cluster and distance analyses revealed the presence

556

Figure 1. Dendrogram of 160 faba bean accessions collected from different agro-ecologies based on average linkage hierarchical cluster analysis between groups.

557 Table 4. Pair wise generalized squared distances (D2) among 160 faba bean accessions in seven clusters. Cluster

C1

C2

C3

C4

C5

C6

C7

C1 C2 C3 C4 C5 C6 C7

0

16 0

66** 28** 0

52** 12 35** 0

19 15 25** 44** 0

94** 34** 32** 12 64** 0

152** 78** 95** 33** 140** 34** 0

**

Indicates highly significant difference (P < 0.01).

Table 5. Clustering pattern of faba bean accessions from different origins over seven clusters. Origin

North Wello South Wello North Gonder North Shewa Arsi

No. of accessions 19 10 40 41 50

No.of accessions in each cluster C1

C2

C3

C4

C5

C6

C7

16 9 28 38 3

3 1 12 3 14

– – – – 9

– – – – 16

– – – – 3

– – – – 3

– – – – 2

of more intra-regional diversity in Arsi as compared to other parts of the country. Collections from Arsi were distributed over all clusters, indicating the existence of more genetic diversity in this region as compared to the others and accessions from the same origin might have different genetic background. The report that faba bean accessions from Welo and Shewa were rather more diverse than those from other regions of the country including Arsi (Dawit et al. 1994) should carefully be reexamined. The small proportions of accessions from Arsi in the population they studied might be the main reason for the discrepancy rather than inadequacy of genetic diversity among collections from Arsi. The reason for similarities in geographical patterns of diversity between Ethiopian field pea and faba bean landraces is not clear from this study and further investigation may be needed. It is also hardly possible to give precise reasoning for the higher genetic diversity in populations collected from Arsi as opposed to the ones from the northern parts of the country. The materials from Arsi might have originally been introduced from different sources. There are indications that the

equina and the major botanical varieties of faba bean have been introduced to Ethiopia in the 19th century after the first introduction of the smallseeded (var. minor) types immediately after the domestication of the crop (Westphal 1974; Asfaw et al. 1994). However, the route of introduction was not clearly stated. The considerable genetic diversity in the southern part of the country might be explained in terms of the introgression into the minor types by the lately introduced equina and the major types. The crop also might have been forced to evolve in different direction through local breeding for different targets in the same region. Farmers could play important roles in the dynamics of genetic diversity by providing opportunities for hybridization by bringing together geographically and ecologically isolated landraces and selection for desirable agronomic traits (Teshome et al. 1997). Higher genetic diversity in collections from Arsi as compared to those from Welo and Gojam was also reported in barley (Demissie and Bjørnstad 1997). The pairwise generalized squared distances between accessions from Arsi origin in clusters C1 with clusters C4–C7 were highly significant and crosses between the intra-regional groups with significant genetic diversity are expected to result in good level of genetic recombination and generate desirable segregants with broad genetic base. Therefore, not only inter-regional diversity but also intra-regional diversity should be a useful component in faba bean hybridization programs and differences in geographic origins should not necessarily be used as an index of genetic distance in parental selection. Previous workers in faba bean also suggested that differences in geographic origin should not be strictly used as an index of genetic distance (Sindhu 1985). Some partial overlapping were encountered between accessions from Arsi and those from the northern extremes of the country. Cluster C1, for instance, comprised accessions from North and South Wello, North Gonder, North Shewa and Arsi. This again indicates that accessions from different regions may share similar genetic background for reasons mentioned above. However, it seems that accessions from the northern part of the country and those from the southern part have different genetic background in most of the cases. This different pattern of diversity is probably attributed to the differences in the nature of

558 both human and natural selections. Rainfall distribution is the most variable elements of climate between the two parts of the country (EMA 1988; Asfaw et al. 1994) and suitable zones of faba bean production follow the pattern of rainfall distribution (Asfaw et al. 1994). Therefore, this study may partially support the hypothesis that the ecological environment is the major force in crop evolution (Spagnoletti Zeuli and Qualset 1987). Cluster means indicated the differences among the clusters for most of the traits (Table 6). Cluster Ci constituted inferior accessions (most susceptible to chocolate spot, the shortest in plant height, and least in number of node/plant, number of seeds/pod, 1000 seed weight and grain yield) for most of the traits. Clusters C2, C4 and C5 comprised intermediate accessions for most of the traits. Cluster C3 was characterized by the least number of podding nodes/plant and number of pods/plant and by the largest seed size. Clusters C6 and C7 constituted superior accessions for most of the traits including chocolate spot resistance, larger seed size and higher grain yield. It is, therefore, advisable that selection of parents should consider not only the distance between clusters but also the special merits of each cluster and each accession within a cluster depending on the specific objectives of hybridization as suggested by Singh (1990). The accessions in clusters superior for most of the traits including chocolate spot resistance, lar-

ger seed size and higher grain yield are all from Arsi. Accessions collected from Arsi revealed not only the presence of more intra-regional diversity as compared to other parts of the country but also some important traits for future collection, conservation and utilization in breeding programs. This concurs with the report of Amare (1990) who stated that accessions with relatively larger seeds dominate in the southern while small-seeded types dominate in the northern parts of the country but contrasts that of Asfaw et al. (1994). It rather seems difficult to explore the existence of the relatively large-seeded types here and there all over the country as producers usually grow them isolated in their garden to keep them away from green pod consumption by passengers. Various workers in Ethiopia also reported an indication for concentration of desirable genes in a particular region in different crop species (Demissie and Bjørnstad 1997; Nigussie 2001) including faba bean (Dawit et al. 1994). Principal component analysis (PCA) showed that the first five principal components accounted for 89% of the total variation, of which 64% was contributed by the first two principal components (PRIN1 and PRIN2) (Table 7). PRIN1 contributed nearly 43% while PRIN2 contributed about 21% of the total variation. It is normally assumed that characters with larger absolute values closer to unity within the first principal component influence the clustering more than those with lower absolute values closer to zero (Chahal and Gosal

Table 6. Cluster means for 11 characters in faba bean accessions. Character

Days to flowering Days to maturity Grain filling period Plant height Chocolate spot No. of nodes/plant No. of podding nodes/plant No. of pods/plant No. of seeds/plant 1000 seed weight Grain yield/plot *

Lowest value. Highest value.

**

Cluster

Grand mean

C1

C2

C3

C4

C5

C6

C7

52 132* 80 95* 4.64** 28* 5.56 7.41 2.59* 306* 106*

54 134 80 106 4.09 29 6.25 8.36 2.76 383 192

51* 135** 84** 112 3.79 31 5.19* 6.48* 2.97 511** 215

53 133 81 111 3.63 30 7.19 10.02 2.92 416 271

55** 134 79* 113 3.87 31 5.30 6.97 2.92 434 141

55** 134 79* 114 3.57 29 6.93 9.23 3.08** 495 304

53 134 82 116** 3.50* 34** 8.53** 11.93** 3.00 417 395**

53.29 133.71 80.71 109.57 4.46 30.29 6.42 8.63 2.89 423.14 232.00

559 Table 7. Percentage and cumulative variances and Eigenvectors on the first five principal components for 11 characters in 160 faba bean accessions. Parameter

PRIN1

Eigenvalue % variance Cumulative Character Days to flowering Days to maturity Grain filling period Plant height Chocolate spot No. of nodes/plant No. of podding nodes/plant No. of pods/plant No. of seeds/pod 1000 seed weight Grain yield/plot

4.729 42.99 42.99 Eigenvectors 0.144 0.226 0.013 0.376 0.396 0.285 0.278 0.259 0.322 0.360 0.414

2002). Accordingly, most of the characters individually contributed small effects (±0.013–0.414) to the total variation and, therefore, the differentiation of the accessions into different clusters was rather dictated by the cumulative effects of a number of characters. Characters with relatively greater weight in PRIN1 like grain yield, chocolate spot infestation level, plant height, 1000 seed weight and number of seeds/pod had higher relative contribution to the total diversity and they were the ones that most differentiated the populations.

Conclusions Like in field pea, it was revealed that genetic diversity in this species was also not uniformly distributed across the regions. It was also observed that accessions of both crops from the northern part of the country were closely related regardless of their geographic origin while those from Arsi had different genetic background. The reason for this is not clear from this study. Probably the level of genetic diversity in the original introductions may vary among regions. The nature and degree of natural and artificial manipulations after introductions, which may vary among regions, could also play an important role both in the dynamics of creation and perpetuation of genetic diversity. The concept that difference in geographic origin should be used as

PRIN2

PRIN3

PRIN4

PRIN5

2.333 21.21 64.20

1.302 11.84 76.04

0.784 7.13 83.16

0.653 5.93 89.10

0.561 0.225 0.521 0.183 0.155 0.080 0.374 0.372 0.045 0.056 0.125

0.320 0.176 0.478 0.091 0.103 0.119 0.435 0.460 0.139 0.430 0.031

0.014 0.805 0.225 0.049 0.111 0.323 0.026 0.098 0.331 0.186 0.169

0.042 0.293 0.072 0.217 0.062 0.869 0.136 0.217 0.075 0.055 0.165

an index of genetic diversity in parental selection could not reliably be used as a strategy and parental selection should rather be made based on systematic assessment of genetic distance in a specific population. Future collection missions and conservation strategies should prioritize Arsi to safeguard the tremendous genetic diversity from genetic erosion and ensure the sustainable perpetuation of these valuable resources. Breeding programs should also focus on effective and efficient exploitation of not only inter-regional diversity in the country as a whole but also intra-regional diversity in Arsi. Inter-cluster gene recombination of sample accessions drawn from the significantly distant clusters followed by selection should prove to generate agronomically desirable progenies as expected.

Acknowledgements We appreciate the assistance of the Institute of Biodiversity Conservation and Research, and Adet, Sheno and Sirinka Agricultural Research Centers in germplasm collection. We also wish to thank the staff of the Highland Pulses Research Program at Holetta and Kulumsa Agricultural Research Centers for data collection and Dr Woldeyesus Sinebo for reviewing the first draft of the manuscript.

560 References Amare Ghizaw 1990. Evaluation of Faba Bean (Vicia faba L.) Production Packages on Farmers Fields in Arsi Administrative Region. MSc Thesis, Alemaya University of Agriculture, Ethiopia. Arunachalam V., Bandyopadhyay A., Nigam S.N. and Gibbons R.W. 1984. Heterosis in relation to genetic divergence and specific combining ability in groundnut (Arachis hypogaea L.), Euphytica 33: 33–39. Arunachalam V. and Bandyopadhyay A. 1984. Limits of genetic divergence for occurrence of heterosis-experimental evidence from crop plants. Indian J. Genet. 44(3): 548–554. Asfaw Tilaye, Tesfaye Getachew and Beyene Demtsu 1994. Genetics and breeding of faba bean. In: Asfaw Tilaye, Geletu Bejiga, Saxena M.C. and Solh M.B. (eds), Cool-Season Food Legumes of Ethiopia. Proceeding of the First National CoolSeason Food Legumes Review Conference, 16–20 December 1993, Addis Ababa, Ethiopia. ICARDA/IAR. ICARDA, Syria, pp. 97–121. Bartual R., Carbonell E.A. and Green D.E. 1985. Multivariate analysis of a collection of soybean cultivars for southeastern Spain. Euphytica 34: 113–123. Bond D.A. 1976. Field beans Vicia faba. In: Simmonds N.W. (eds), Evolution of Crop Plants. Longman, London, pp. 179– 182. Bunder J., Loeber A., Broers J.E.W. and Havertkort B. 1996. An integrated approach to biotechnology development. In: Bunders J., Haverkort B. and Hiemstra W. (eds), Biotechnology; Building on Farmers’ Knowledge. Macmillan, London and Basingstoke, pp. 201–227. Ceccarelli S. 1994. Specific adaptation and breeding for marginal conditions. Euphytica 77(3): 205–219. Chahal G.S. and Gosal S.S. 2002. Principles and Procedures of Plant Breeding: Biotechnological and Conventional Approaches. Narosa Publishing House, New Delhi. Cubero J.I. 1974. On the evaluation of Vicia faba L. Theor. Appl. Genet. 45: 47–51. Dale M.F.B., Ford-Lloyd B.V. and Arnold M.H. 1985. Variation in some agronomically important characters in a germplasm collection of beet (Beta vulgaris L.). Euphytica 34: 449–455. Dawit Tadesse, Asfaw Tilaye and Geletu Bejiga 1994. Genetic resources in Ethiopia. In: Asfaw Tilaye, Geletu Bejiga, Saxena M.C. and Solh M.B. (eds), Cool-Season Food Legumes of Ethiopia. Proceeding of the First National Cool-Season Food Legumes Review Conference, 16–20 December 1993, Addis Ababa, Ethiopia. ICARDA/IAR. ICARDA, Syria, pp. 79–96, Vii + 440pp. de Boef W.S., Berg T. and Haverkort B. 1996. Crop genetic resources. In: Bunders J., Haverkort B. and Hiemstra W. (eds), Biotechnology; Building on Farmers’ Knowledge. Macmillan, London and Basingstoke, pp. 103–128. Demissie A. and Bjørnstad A. 1997. Geographical, altitude and agro-ecological differentiation of isozyme and hordein genotypes of landrace barleys from Ethiopia: implications to germ-plasm conservation. Genet. Resour. Crop Evol. 44: 43– 55. Durga Prasad M.M.K., Arunachalam V. and Bandyopadyay A. 1985. Diversity pattern elucidating parents for hybridiza-

tion in varieties of groundnut, Arachis hypogaea L. Trop. Agric. 62: 237–242. EMA 1988. National atlas of Ethiopia. Ethiopian Mapping Authority (EMA), Addis Ababa. Engels J.M.M. and Hawkes J.G. 1991. The Ethiopian gene center and its genetic diversity. In: Engels J.M.M., Hawkes J.G. and Melaku Worede (eds), Plant Genetic Resources of Ethiopia. Cambridge University Press, pp. 23–41. Gemechu Keneni, Belay Simane and Getinet Gebeyehu 1997. Genetic diversity of groundnut germplasm in Ethiopia. Ethiop. J. Agri. Sci. 16(1&2): 1–13. Hailu Mekibeb, Abebe Demissie and Abebe Tullu 1991. Pulse crops of Ethiopia. In: Engels J.M.M., Hawkes J.G. and Melaku Worede (eds), Plant Genetic Resources of Ethiopia. Cambridge University Press, pp. 328–343. Harlan J.R. 1975. Crops and Man. ASA and CSSA, Madison, WI. Hawkes J.G. 1983. The Diversity of Crop Plants. Harvard University Press, 1984 p. Jaradat A.A. 1991. Phenotypic divergence for morphological and yield related traits among landrace genotypes of durum wheat from Jordan. Euphytica 52: 155–164. Joshi A.B. and Dhawan N.L. 1966. Genetic improvement in yield with special reference to self-fertilizing crops. Indian J. Genet. 26A: 101–103. Katule B.K., Thombare M.V., Dumbre A.D. and Pawar B.B. 1992. Genetic diversity in bunch groundnut. J. Maharashtra Agri. Univ. 17: 302–303. Nadaf H.L., Habia A.F. and Goud J.V. 1986. Analysis of diversity in bunch groundnut. J. Oilseeds Res. 3: 37–45. Nechit M.M., Ketata H. and Yau S.K. 1988. Breeding durum wheat for stress environments of the Mediterranean region. In: Wittmer G. (ed.), Proceedings of the Third International Symposium on Durum Wheat, ‘The Future of Cereals for Human Feeding and Development of Biotechnological Research’, Publ. Chamber of Commerce, Foggia, Italy, pp. 297– 304. Nigussie Alemayehu 2001. Germplasm Diversity and Genetics of Quality and Agronomic Traits in Ethiopian Mustard (Brassica carinata A. Braun). Doctoral Dissertation, GeorgAugust University of Gottingen, Germany. Reddy P.S. 1988. Genetics, breeding and varieties. In: Reddy P.S. (ed.), Groundnut. Publication and Information Division, Indian Council of Agricultural Research, Krishi Anusandhan Bhavan, Pusa, New Delhi, pp. 200–317. Rezai A. and Frey K.J. 1990. Multivariate analysis of variation among wild oat accessions-seed traits. Euphytica 49: 111– 119. Russell G.E. 1978. Plant Breeding for Pest and Diseases Resistance. Butterworths, London. Sindhu J.S. 1985. Multivariate analysis in faba bean (Vicia faba L.). FABIS No. 12: 5–7. Singh B.D. 1990. Plant Breeding: Principles and Methods. Kalyani Publishers, New Delhi-Ludhiana. Singh R.K. and Chaudhary B.D. 1985. Biometrical Methods in Quantitative Genetic Analysis. Kalyani Publishers, New Delhi–Ludhiana. Spagnoletti P.L. and Qualset C.O. 1987. Geographical diversity for quantitative spike characters in a world collection of durum wheat. Crop Sci. 27: 235–241.

561 Teshome A., Baum B.R., Fahrig L., Torrance J.K., Arnason T.J. and Lambert J.D. 1997. Sorghum [Sorghum bicolor (L.) Moench] landrace variation and classification in North Shewa and South Welo, Ethiopia. Euphytica 97: 255–263.

Westphal E. 1974. Pulses in Ethiopia: Their Taxonomy and Significance. College of Agriculture, Haile Sellessie I University, Ethiopia/Agriculture University, Wageningen, The Netherlands.