The aim of this study was to investigate the amount of heterosis and performance of faba bean synthetic cultivars compared to line cultivars under semi-arid conditions. Five inbred lines in at least S 6 generation were developed and used to develop <i> F </i> 1 s hybrid (in all possible combination excluding reciprocal), lines mixtures (Syn-0) and synthetic generations of Syn-1. Evaluation of the entries showed the lines to have high general and specific combining ability, high yield and high average degree of cross-fertilization (0.36); hetrosis relative to mid-parent for yield was 67%. Lines mixture from four inbred lines (Hudeiba/93, Bassabier, Ed-Damar and Shabah) gave the highest yield of 3.40 t/ha for Syn-0 and 3.96 t/ha for Syn-1. Compared to the average yield t/ha of the pure stand of the four lines (3.11 t/ha), the increase in yield of was 9% in sy-0 and 27% in Syn-1. Compared to the individual yield t/ha of the pure stand of the lines, the performance of Syn-0 surpassed that of the individual pure stands of the linesby 14% for Hudiaba/93 and Bassabier and 4% for Ed-Damar and 7% for Shabah, whereas the increase in performance of Syn-1 compared to pure stand of the lines was 32%, 25% and 21 % , respectively. The results confirm the previous knowledge on yield increase with successive syn-generations in faba bean due to the effects of heterogeneity and heterozygosity. Such results could be used as a base for an effective breeding program for improvement of yield of faba bean grown under the semi-arid zone s .
Faba bean is the most important food legume crop in North (Morocco, Egypt and Sudan) and East (Ethiopia) Africa. It contributes to the main human nutrition, supplying high quality protein crucial for a balance diet of millions of people who cannot afford meat as a source of protein. In addition, faba bean has been shown to increase soil fertility through biological N2-fixation that can be used by the succeeding cereal crops and to break the cycle of biotic stresses [
To produce stable and high yield in faba bean, synthetic cultivars were recommended [
Five inbred lines (in at least S6 generation) developed via single seed decent from the five locally grown faba bean cultivars in Sudan (Selaim, Hudeiba/93, Ed-Damar, Bassabier, and Shabah), representing a wide range of genetic variability in their agronomic traits (plant height, number of pods/plant, 100 seed weight, and yield), were used to fulfill the objectives of the present study. These lines were sown in isolated cages for multiplication (by hand tripping) and for cross purposes by hand in all possible combinations (in diallel cross excluding reciprocals) to produce F1 seeds.
Three experiments were carried out at the Demonstration Farm of the Faculty of Agriculture, University of Khartoum, Shambat (latitude 15˚40'N; longitude 32˚32'E, and altitude 380 meter above sea level). The site is located in the semi-arid zone; the soil is alkaline (pH 8.0); rainfall is about 150 mm per annum and with maximum temperature of about 42˚C in summer and around 21˚C in winter [
In experiment I, the seeds of the lines (parents) and F1s were grown in seasons 2014/2015-2015/2016 to test the lines for general (GCA) and specific (SCA) coming ability.
In experiment II, the lines were evaluated in seasons 2014/2015-2015/2016 for the degree of cross-fertilization as described by Link [
In experiment III, an equal number of seeds (25 seeds) from each of the five inbred lines [Hudeiba/93 (L1), Ed-Damar (L2), Shabah (L3), Bassabeir (L4) and Selaim (L5)] were blended in all possible combination. Accordingly, sixteen blends/mixtures (M1 to M16) were developed. The line blends (one from all lines, five blends from four lines and ten blends from three lines) called Syn-0, were grown in season 2014/2015 under open pollination in spatial isolation to produce Syn-1seed. The seed of the lines blend (Syn-0) and that of Syn-1 were grown in season 2015/2016 and evaluated for yield and yield components.
Complete randomized block design with three replicates was used to execute the experiments. The gross plot size in the two experiments was 6.3 m2 consisting of 3 ridges each 3 m in length and 70 cm apart. One seed was planted per hole with the spacing of 10 cm along the ridge. The experimental plots were irrigated every 14 days and weeded three times using hand hoe. The experiment was carried out in the presence of pollinators; here honeybee (Apis mellifera sp.) was introduced in the field of the experimental area.
Data were collected from the parameters of: 1) days to flowering, determined when 50% of the plants of each entry open the first flower, 2) Plant height measured in cm at the end of the flowering period, 3) Number of pods per plant, 4) 100-seed weight (g), and 5) seed yield t/ha. The data were subjected to analysis of variance (ANOVA) according to the method described for the randomized complete block design (RCBD). The computer program SAS-1997version 9.0 was used for the analysis of variance.
The heterotic effects of F1 crosses were estimated as a percentage over mid parent [
Relative heterosis (RH) (%) = F 1 − Midparent Midparent × 100
Data for general combining ability (GCA) and specific combing ability (SCA) were analyzed as described by [
Y i j = μ + G C A i + G C A j + S C A i j + e i j k l
where:
Yij = Observation of ith parent in the jth block;
µ = population mean;
GCAi = general combining ability (g.c.a) effect of the ith parent;
GCAj = general combining ability (g.c.a) effect of the jth parent;
SCAij = specific combined effect (s.c.a) of two parents;
eijkl = experimental error.
The standard error required for testing the significance of general combining ability effects of the parents (p) and differences of GCA effects were obtained as:
S.E.ĝi = ( ( P − 1 ) p ( p + 2 ) σ e 2 ) 1 / 2
and S.E.(ĝi - ĝj) = ( 2 p + 2 σ e 2 ) 1 / 2
Three errors required for testing the significance of specific combining ability effect of the parents (p) and differences of SCA effects were estimated as:
S.E.ŝij = ( P 2 + P + 2 ( p + 1 ) ( p + 2 ) σ e 2 ) 1 / 2
S.E.(ŝij - ŝik) = ( 2 ( P + 1 ) ( p + 2 ) σ e 2 ) 1 / 2
and S.E.(ŝij - ŝkl) = ( 2 P p + 2 σ e 2 ) 1 / 2
Mean squares from the analysis of variance for the studied traits in the 15 entries (parental lines and their F1s) revealed highly significant differences, except for number of days to 50% flowering which exhibited non-significant differences (data not shown). Comparing the crosses performance with their corresponding parental lines, none of the lines exceeded hybrid performance in any of the studied traits (
Mean squares from the analysis of variance for GCA and SCA for the studied traits are presented in
For SCA, the magnitude of the crosses varied for the different traits e.g. the cross of Ed-Damar × Bassabier (L2 × L4) showed the largest (33.52 cm) positive SCA effect for plant height and number of pods per plant (26.42); the cross of Shabah × Selaim (L3 × L5) exhibited the largest (26.02) positive SCA effect for 100-seed weight (
Entry/trait | Days to flowering | Plant height (cm) | Pods/plant | 100-seed weight (g) | yield (t/ha) |
---|---|---|---|---|---|
Hudeiba/93 (L1) | 45.30 | 74.40 | 25.13 | 55.80 | 2.99 |
Ed-Damar (L2) | 45.00 | 72.50 | 24.90 | 57.63 | 3.17 |
Shabah (L3) | 45.00 | 73.00 | 20.60 | 71.40 | 3.27 |
Bassabeir (L4) | 45.30 | 72.60 | 27.00 | 55.43 | 2.99 |
Selaim (L5) | 44.30 | 70.00 | 18.37 | 67.30 | 2.96 |
Mean | 44.98 | 72.50 | 23.20 | 61.51 | 3.07 |
L1 × L2 (F1-1) | 45.30 | 84.73 | 42.00 | 68.77 | 5.10 |
L1 × L3 (F1-2 | 44.70 | 88.70 | 37.00 | 68.90 | 5.20 |
L1 × L4 (F1-3) | 45.00 | 85.16 | 39.00 | 68.50 | 5.11 |
L1 × L5 (F1-4) | 45.70 | 79.23 | 35.00 | 69.30 | 4.90 |
L2 × L3 (F1-5) | 45.30 | 80.00 | 37.00 | 71.97 | 5.20 |
L2 × L4 (F1-6) | 46.00 | 83.20 | 49.00 | 69.13 | 5.60 |
L2 × L5 (F1-7) | 45.70 | 81.40 | 36.00 | 70.37 | 5.00 |
L3 × L4 (F1-8) | 45.70 | 77.80 | 37.00 | 69.00 | 5.23 |
L3 × L5 (F1-9) | 45.30 | 78.30 | 33.00 | 73.60 | 5.25 |
L4 × L5 (F1-10) | 45.30 | 76.00 | 35.00 | 70.80 | 4.70 |
Mean | 45.40 | 81.50 | 38.00 | 70.03 | 5.14 |
Gran mean | 45.25 | 76.62 | 31.6 | 66.90 | 4.10 |
C.V | 3.02 | 4.13 | 3.09 | 1.94 | 8.01 |
LSD0.05 | - | 2.61 | 0.94 | 1.24 | 0.34 |
Source of variation | Degree of freedom | Plant height (cm) | Pods/plant | 100-seed weight (g) | Yield (t/ha) |
---|---|---|---|---|---|
GCA | 4 | 4820.83** | 1034.87** | 3501.66** | 21.61** |
SCA | 10 | 338.88** | 112.99** | 235.90** | 1.61** |
Error | 18 | 5.719 | 0.495 | 0.261 | 0.098 |
** = significant difference at 0.01.
Line/trait | Plant height (cm) | Pods/plant | 100-seed weight (g) | Yield t/ha |
---|---|---|---|---|
Hudeiba/93 (L1) | 0.94 | 0.77 | −0.41 | 0.02 |
Ed-Damar (L2) | 0.29 | 0.52 | 0.14 | 0.05 |
Shabah (L3) | −0.28 | −1.64 | 0.51 | 0.05 |
Bassabeir (L4) | 0.12 | 1.29 | −0.62 | 0.08 |
Selaim (L5) | −0.06 | −0.94 | 0.39 | −0.19 |
S.E.ĝi | 0.81 | 0.36 | 0.17 | 0.11 |
S.E.(ĝi − ĝj) | 1.28 | 0.57 | 0.27 | 0.17 |
** = significant difference at 0.01.
Cross/trait | Plant height (cm) | Pods/plant | 100-seed weight (g) | Yield t/ha |
---|---|---|---|---|
L1 × L2 | 32.17 | 13.66 | 22.73 | 2.04 |
L1 × L3 | 28.58 | 12.96 | 23.59 | 1.87 |
L1 × L4 | 22.46 | 6.89 | 23.26 | 1.87 |
L1 × L5 | 30.08 | 20.32 | 22.11 | 1.64 |
L2 × L3 | 22.20 | 7.18 | 23.31 | 2.12 |
L2 × L4 | 33.52 | 26.42 | 23.11 | 1.72 |
L2 × L5 | 22.81 | 5.55 | 24.76 | 1.65 |
L3 × L4 | 25.63 | 12.77 | 22.44 | 2.13 |
L3 × L5 | 27.98 | 11.27 | 26.02 | 1.40 |
L4 × L5 | 28.41 | 9.84 | 22.05 | 1.90 |
S.E.ŝij | 14.6 | 0.49 | 3.10 | 1.91 |
S.E.(ŝij − ŝik) | 2.39 | 0.7 | 0.51 | 0.31 |
S.E.(ŝij − ŝik) | 1.95 | 0.57 | 0.41 | 0.26 |
** = significant difference at 0.01.
Values of heterosis percentage relative to mid parents for the studied traits are presented in
Cross/trait | Plant height (cm) PH | Pods/plant | 100-seed weight (g) | Yield t/ha |
---|---|---|---|---|
L1 × L2 | 16.15 | 67.90 | 21.24 | 65.58 |
L1 × L3 | 21.20 | 61.82 | 5.30 | 66.13 |
L1 × L4 | 17.00 | 50.00 | 23.20 | 67.22 |
L1 × L5 | 9.74 | 61.00 | 7.70 | 72.00 |
L2 × L3 | 9.97 | 62.64 | 7.45 | 61.50 |
L2 × L4 | 15.00 | 89.00 | 12.61 | 82.00 |
L2 × L5 | 13.50 | 66.40 | 7.90 | 60.00 |
L3 × L4 | 6.87 | 55.50 | 5.60 | 67.09 |
L3 × L5 | 8.75 | 69.40 | 4.25 | 68.27 |
L4 × L5 | 6.00 | 54.29 | 9.45 | 58.00 |
Mean | 12.33 | 64.00 | 10.50 | 67.00 |
Lines | Degree of cross-fertilization |
---|---|
Mean Range LSD C.V Mean squares | 36.0 ± 7.8 28.1 - 46.9 3.9 10.4 169.64** |
**Significance at 0.01.
Mean squares from the analysis of variance (
To improve yield potentials of a crop, in breeding program, it is important to create new combinations of genes to produce genotype with trait performance that is superior to current genotypes at the target environment [
blend/trait | Plant height (cm) | pods/plant | 100-seed weight (g) | Yield t/ha | ||||||
---|---|---|---|---|---|---|---|---|---|---|
SYN-0 | Syn-1 | Syn-0 | Syn-1 | Syn-0 | Syn-1 | Syn-0 | Syn-1 | |||
M1 | 70.40 | 89.2 | 22 | 26 | 50.60 | 50.60 | 2.59 | 3.27 | ||
M2 | 72.60 | 82.10 | 24 | 29 | 52.20 | 55.20 | 3.40 | 3.96 | ||
M3 | 70.90 | 83.90 | 25 | 27 | 57.80 | 57.90 | 2.73 | 3.01 | ||
M4 | 70.80 | 82.20 | 23 | 25 | 50.00 | 50.10 | 2.64 | 2.94 | ||
M5 | 69.50 | 86.30 | 24 | 28 | 53.10 | 53.10 | 2.64 | 3.22 | ||
M6 | 69.80 | 85.30 | 24 | 26 | 51.60 | 51.70 | 2.75 | 3.04 | ||
M7 | 69.00 | 89.10 | 25 | 28 | 53.90 | 53.90 | 2.82 | 3.22 | ||
M8 | 76.60 | 88.10 | 24 | 26 | 47.20 | 47.20 | 2.82 | 2.92 | ||
M9 | 65.50 | 80.50 | 23 | 26 | 49.90 | 50.80 | 2.88 | 2.95 | ||
M10 | 70.70 | 90.50 | 24 | 26 | 55.20 | 58.50 | 2.63 | 2.84 | ||
M11 | 63.90 | 85.20 | 21 | 24 | 51.50 | 52.80 | 2.13 | 2.39 | ||
M12 | 66.60 | 91.80 | 23 | 26 | 52.90 | 53.90 | 2.42 | 3.10 | ||
M13 | 69.20 | 92.90 | 22 | 29 | 57.40 | 57.40 | 2.66 | 2.96 | ||
M14 | 69.80 | 89.90 | 23 | 27 | 55.50 | 58.90 | 2.63 | 2.91 | ||
M15 | 73.00 | 83.60 | 25 | 26 | 46.60 | 46.60 | 2.26 | 2.82 | ||
M16 | 71.50 | 88.90 | 22 | 27 | 51.30 | 54.10 | 2.35 | 2.87 | ||
Mean | 69.99 | 86.84 | 23.38 | 26.50 | 52.30 | 53.29 | 2.68 | 3.01 | ||
C.V | 7.31 | 8.41 | 7.48 | 11.54 | ||||||
LSD0.05 | 8.53 | 3.6 | 3.8 | 0.28 | ||||||
of a wide genetic variability among the lines and F1-hybrids produced from them; indicating that the genetic improvement is possible in the present genetic material. Moreover, the wide range in the mean performance for the traits: plant height, number of pods per plant, 100-seed weight and yield; among the entries accompanied with high heritability (broad-sense) of 0.71 - 0.95 confirm the presence of sufficient genetic variability and possibility of selection and improvement of yield and yield traits in the present faba bean germplasm. Similar results were reported by [
In any breeding program, it is very important to know the combining abilities of the inbred lines that are used as parents in hybrids [
In the present investigation, the highly significant mean squares for both general combining ability (GCA) and specific combining ability may indicate the importance of both additive and dominance gene effect in the inheritance of the studied traits. Moreover, the higher mean squares from the analysis of variance for GCA of the traits than of SCA showed the great contribution of the additive effects of genes in the expressions of the traits. Therefore, selection will be effective for improvement of yield and yield traits in the present genetic material. Several researchers have reported on the significance of both general and specific combining ability effects on yield and yield traits in faba bean and found similar results, e.g. [
Form the results, the highest GCA given by Hudeiba/93 line for plant height, number of pods per plant and number of seeds per pod and the highest GCA exhibited by Shabah line for 100-seed weight as well as that showed by Bassabier line for pods per plant and yield (t/ha), indicate that these lines are the good combiner for the mentioned traits; therefore the improvement of such traits is rather predictive and more heterosis and high yield performance could be expected upon crossing. These findings are in agreement with those reported by [
In the present study the high degree of cross-fertilization of 36% and high heterosis (67%) exhibited by the lines under the study as well as their highly significant positive GCA and SCA indicate the presence of the prerequisites for production of synthetic cultivars. For the number of parental lines, the high and significant performance for yield and yield traits obtained by mixture M2 (the mixture of Hudeiba/93, Bassabier, Ed-Damar and Shabah lines) in Syn-0 and Syn-1 compared to performance of each of the line, indicate that synthetic cultivars could be developed from these four lines. Moreover, the increase in overall yield performance from 3.40 t/ha in Syn-0 to 3.96 in Syn-1 indicates the effect of heterozyosity as well as the joint effect of heterogeneity and hetrozygosity in Syn-1, which is expected to increase and give high yield performance in Syn-2 and Syn-3 [
The authors declare no conflicts of interest regarding the publication of this paper.
Gasim, S.M. and Mohamed, A.E. (2018) Heterotic Effect, Combining Ability and Significance of Synthetics over Line Cultivars in Faba Bean (Vicia faba L.) Grown under Semi-Arid Zones. American Journal of Plant Sciences, 9, 2684-2695. https://doi.org/10.4236/ajps.2018.913195