ajps American Journal of Plant Sciences 2158-2742 2158-2750 Scientific Research Publishing 10.4236/ajps.2025.161015 ajps-140357 Articles Biomedical Life Sciences Study on Combining Ability for Yield and Yield Contributing Characters of Short Statured Maize Inbred Lines at over Locations Mohammad Motasim Billah 1 Mohammad Quamrul Islam Matin 1 Mohammad Zahirul Alam Talukder 1 Mohammed Harun or Rashid 1 Mohammad Khorshed Alam 1 Seuli Sharmin 2 Praneetha Subramanyam 3 Muhammad Ibrar 4 aPlant Breeding Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh aDepartment of Crop Physiology and Ecology, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh aHorticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore, India aAgriculture Extension Office, Karak, Pakistan 09 01 2025 16 01 170 179 22, September 2024 27, September 2024 27, January 2025 © Copyright 2014 by authors and Scientific Research Publishing Inc. 2014 This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Twenty short-statured maize inbred lines were collected from CIMMYT India and Mexico through the Plant Breeding Division, Bangladesh Agricultural Research Institute (BARI), Gazipur. The experiment was conducted from November 2020 to April 2021 in three different agroecological regions such as BARI, Gazipur, RARS Barisal and RARS Rangpur. Seven inbred lines were selected on the basis of genetic diversity and per se performance and they were crossed separately in a 7 × 7 half diallel fashion, producing 21F 1 hybrids in 2019 which were evaluated at three locations. However, variances due to GCA were much higher in magnitude than SCA for all the characters indicating preponderance of additive gene effects on the inheritance of these characters. Two parents viz., P 3 (CML33) and P 4 (CML41) were good general combiners and two crosses viz., P 4 × P 5 (CML41 × CML31) and P 5 × P 7 (CML31 × CML124) expressed significant positive SCA effects coupled with significant positive heterosis for grain yield and for most of the yield contributing characters over the two commercial check varieties BHM 9 and NK40. Four crosses: P 1 × P 5 (CML116 × CML31), P 1 × P 6 (CML116 × CML32), P 2 × P 6 (CML72 × CML32) and P 3 × P 4 (CML33 × CML41), exhibited significant and negative SCA effects for both plant and ear height which were desirable for short stature. Genotypes x location interaction was also significant for maximum characters, suggesting that genotypes interacted significantly in different environments. Combining Ability GCA SCA Gene Action Maize 1. Introduction

Maize (Zea mays L., 2n = 20) ranks as the third most important cereal crop next to wheat and rice in production in the world. Maize is suitable to diverse environments though it is native to Central America. The crop expands new areas and environments continuously and thus, it explores Asia. The demand of maize increased gradually during nineties with the expansion of the poultry industry and this is why maize yields increased from an average of less than 1 ton per hectare for several decades through 1992 to more than 6 tons per hectare in 2010 by the introduction of hybrid maize varieties, still it is in increasing trend rapidly. Maize yields per hectare in Bangladesh exceed yields in China and Japan [1] . The increase in net income from hybrids can be estimated by assuming that farmers replace wheat with maize [2] . An earlier estimate in the world, maize production recorded 875 million tons [3] , while 23 lac tons has been produced in Bangladesh, which occupies an area of 3.5 lac hectares [4] with tremendous growth till now. [5] reported that the present production of maize was around 57 lac tons in the area of 5.52 lac hectares with an average yield 10.20 tons/ha. About 30% of world production is used for direct human consumption and as an industrial input, while 70% is used as animal feed [6] . But in Bangladesh, the sole maize (except popcorn and adulteration in wheat flour) is used up by poultry industries. In these circumstances, we, the people of Bangladesh should change our food habits by taking maize directly because both nutritional and medicinal value of maize is higher than rice and wheat. Ones upon a time, there was no hybrid maize variety in Bangladesh to meet the challenge, now Bangladesh Agricultural Research Institute (BARI) has developed some hybrid maize varieties with the help of the International Maize and What Improvement Centre (CIMMYT).

Combining ability estimation is considered an important genetic attribute for maize breeders in anticipating improvement in productivity via hybridization and selection [7] . The value of inbred lines in the commercial production of hybrid maize being determined by two factors, the characteristics of the inbred itself with respect to yielding potentiality, pollen shedding, disease resistance etc., and the behaviour of the line in hybrid combinations as well [8] . To determine GCA and SCA information of white grain maize germplasm for identification of nature of genes action involved in the expression of their quantitative traits, genetic diversity evaluation, suitable parental lines selection for hybridization, heterotic pattern classification, heterosis estimation, and hybrids development, the present investigation was undertaken as the above information can be achieved only by combining ability study [9] - [12] . So, the investigation was carried out to observe the combining ability performances over locations and to select the short statured hybrids.

 2. Materials and Methods

The experiment was conducted during November 2020 to May 2021 at three different locations i.e. Bangladesh Agricultural Research Institute (BARI) Gazipur and two different regional stations i.e., Regional Agricultural Research Stations (RARS) Rahmatpur, Barisal and Burirhat, Rangpur with 21 F1s and 2 commercial hybrids viz., BHM9 and NK40 as check. Gazipur belongs to Agro Ecological Zone (AEZ) no. -28 (Madhupur Tract), Barisal -AEZ 18 (Young Meghna Estuarine Floodplain), Rangpur -AEZ 28 (North Eastern Barind Tract). Twenty maize inbred lines were collected from CIMMYT India, CIMMYT Mexico and Plant Breeding Division of BARI. The pedigree were as follows CML20-2-B (H08R-N8205-4), CML27-2-B (H08R-N8205-7), CML28-2-B (H08R-N8205-9), CML30-2-B (H08R-N8205-13), CML31-2-B (H08R-N8205-15), CML32-2-B (H08R-N8205-17), CML33-1-B (H08R-N8205-18), CML41-2-B (H08R-N8205-20), CML51-2-B (H08R-N8205-22), CML58-1-B (H08R-N8205-23), CML70-2-B (H08R-N8205-28), CML71-2-B (H08R-N8205-31), CML72-1-B (H08R-N8205-32), CML112-1-B (H08R-N8205-38), CML113-1-B (H08R-N8205-39), CML116-1-B (H08R-N8205-42), CML121-1-B (H08R-N8205-43), CML122-1-B (H08R-N8205-44), CML124-1-B (H08R-N8205-45), CML124-2-B (H08R-N8205-46). Among them the following inbreds CML31-2-B, CML32-2-B, CML33-1-B, CML41-2-B, CML72-1-B, CML116-1-B, CML124-2-B were selected and renamed as P05, P06, P03, P04, P02 and P01 during hybridization. Following 7 × 7 diallel fashion 21 F1s were developed in 2019. In every location three separate experiments conducted following balanced alpha lattice design with 3 replications to determine the magnitude of G × E interaction and select stable genotypes across different environments. Each plot comprised of 2 rows 5.0 m long. Spacing adopted was 60 × 20 cm between rows and hills, respectively. One healthy seedling per hill was kept after proper thinning. Fertilizers were applied @ 250, 55, 110, 40, 5 and 1.5 kg/ha of N, P, K, S, Zn, B respectively. Standard agronomic practices were followed and plant protection measures were taken as and when required. Data on days to 50% pollen shedding and silking were recorded on whole plot basis. Ten randomly selected plants were used for recording observations on plant height and ear height. All the plants in 2 rows were considered for plot yield which was later converted to ton per hacter (t/ha). Data were analyzed using Crop stat 7.2 and MS Excel.

 3. Results and Discussion 3.1. Mean Performances of 21 F<sub>1 </sub>Hybrids of Short Statured Maize Inbred Lines

Results of overall mean performance across 3 locations of the crosses are presented in Table 1 . Considering grain yield across locations, two crosses P3 × P5 and P5 × P7out yielded (11.24 & 11.28 t/ha) the check hybrid NK40 (11.02 t/ha) and BHM9 (11.22 t/ha). This was followed by P4 × P7 (10.89 t/ha) and P1 × P4 (10.77 t/ha). Days to tasseling and silking, ranged, from 92.01 to 98.88 and 98.53 to 105.4 days. Plant height was found highest in P5 × P7 (172.5 cm) and lowest in P2 × P6 (73.23 cm). Ear height was found highest in P3 × P6 (64.24 cm) and lowest in P2 × P6 (21.73 cm). Ear length and diameter ranged from 11.02 to 16.62 and 4.37 to 5.70 cm respectively. While 1000-kernel wt. ranged from 322.7 to 413.71 gm.

 3.2. Analysis of Variance (ANOVA) for Combining Ability 21 F<sub>1</sub> Hybrids of Short Statured Maize Inbred Lines

The mean sum of square obtained from combined analysis of variance showed the presence of genetic variability among the crosses and environment for all the characters under study except ear length ( Table 2 ). This indicated the influence of differential environmental factors at different locations on the expression of different characters on short statured maize. Crosses × Environment interaction was also highly significant for all the characters. From the result, it can be concluded that the short statured maize genotypes responded significantly to the environments for yield and other yield-contributing characters.

Combined analysis of variances for combining ability for short-statured maize revealed that general combining ability (GCA) were significant for all the characters except plant height and ear length and specific combining ability (SCA) variance was non-significant for all the characters. Variances due to GCA were much higher in magnitude than SCA for all the characters indicating preponderance of additive gene effects for the inheritance of these traits. Both GCA and SCA effects showed significant interaction with environment for all the traits. This suggested the need of selecting different parental lines for hybrids for different ecological situations. [13] observed that GCA variance was highly significant for grain yield, ear length and diameter and no. of kernel/rows.

The ratio components of GCA to SCA revealed that GCA was higher than SCA for all the parameters except ear diameter (ED) which indicated additive genetic variances among the traits. [14] observed additive genetic variance in ear height, [15] in ear length, [16] in yield components, [17] in days to tasseling, days to silking, plant height, ear height and thousand seed weight.

<xref ref-type="bibr" rid="scirp.140357-"></xref>Table 1. Mean performances of 21 crosses for yield and yield contributing characters of short statured maize inbred lines over three environments during rabi 2020-21.

Cros.

DT (50%)

DS (50%)

EH (cm)

PH (cm)

EL (cm)

ED (cm)

R/C

S/R

TGW

GY (t/h)

P1 × P2

97.50

103.00

38.11

97.99

11.02

4.69

13.86

17.68

360.50

6.430

P1 × P3

95.10

100.25

58.60

143.30

14.59

5.25

13.86

31.22

394.80

9.43

P1 × P4

92.01

98.88

57.50

145.30

14.76

5.26

14.56

36.05

412.10

10.77

P1 × P5

98.88

104.71

25.47

86.31

11.67

4.58

13.86

22.88

353.6

5.967

P1 × P6

97.16

104.03

29.42

85.63

11.26

4.58

13.86

20.81

358.78

6.77

P1 × P7

97.50

102.31

31.24

104.90

13.82

5.08

14.56

26.69

357.06

7.35

P2 × P3

93.39

100.60

53.80

137.5

13.53

5.24

15.94

33.28

413.71

10.15

P2 × P4

92.36

99.56

46.35

128.10

12.98

4.90

14.56

25.65

350.22

6.96

P2 × P5

96.48

101.62

33.99

92.15

11.26

4.69

13.17

23.22

374.20

6.35

P2 × P6

98.19

105.31

21.73

73.23

11.05

4.35

14.56

18.02

351.91

6.99

P2 × P7

98.53

105.40

25.44

86.72

11.19

4.76

12.48

18.72

351.91

6.75

P3 × P4

92.35

98.88

50.81

138.00

13.53

5.40

14.56

26.34

367.36

8.19

P3 × P5

94.42

100.25

58.95

144.10

13.39

5.54

14.56

27.73

369.08

11.24

P3 × P6

95.44

101.62

64.24

143.80

13.32

5.17

13.17

31.2

377.66

9.21

P3 × P7

95.79

103.34

55.72

136.90

15.93

5.45

14.56

36.05

382.81

10.30

P4 × P5

92.35

98.53

58.47

165.10

13.66

5.06

14.56

29.46

333.03

8.81

P4 × P6

93.38

100.6

30.55

115.5

13.94

4.97

13.86

28.77

367.36

9.32

P4 × P7

92.72

98.88

46.00

138.21

13.63

5.07

15.25

29.81

375.95

10.89

P5 × P6

97.50

103.68

40.31

108.60

14.21

4.76

14.56

27.04

343.30

7.01

P5 × P7

95.79

101.62

63.03

172.50

16.62

5.70

14.56

31.8

322.7

11.28

P6 × P7

97.16

102.65

27.36

85.52

10.78

4.37

13.86

21.84

326.16

6.48

BHM9

95.79

103.00

73.95

157.41

14.42

4.92

13.86

24.96

412.00

11.22

NK40

97.16

104.03

77.69

177.82

18.06

5.24

15.25

38.48

362.21

11.02

F-test

**

**

**

**

**

ns

*

**

**

*

Mean

95.86

102.24

43.88

119.14

13.04

4.88

14.07

27.08

342.13

7.78

CV (%)

1.7

2.1

19.3

12.1

11.7

2.33

7

17.1

9.4

13.1

LSD (0.05)

2.6

3.44

13.86

23.59

2.49

0.56

1.60

7.55

52.79

1.63

*, ** and ns indicate 5%, 1% level of significance and nonsignificant respectively; Checks: i) NK40 (commercial hybrid), ii) BHM 9 (BARI hybrid maize 9). DT = Days to Tasseling (50%), DS = Days to Silking (50%), PH = Plant Height (cm), EH = Ear Height (cm), EL = Ear Length (cm), ED = Ear Diameter (cm), R/C = Rows per Cob, S/R = Seeds per Row, TGW = Thousand Grains Weight (gm) and GY = Grain Yield (t/h).

<xref ref-type="bibr" rid="scirp.140357-"></xref>Table 2. ANOVA to test combining ability for yield and yield contributing characters of short statured maize hybrids over three environments during rabi 2020-21.

SV

df

DT (50%)

DS (50%)

PH (cm)

EH (cm)

EL (cm)

ED (cm)

R/C

S/R

TGW

GY (t/h)

Env (E)

2

56.00**

67.65**

42279.3**

18895.1**

15.21

12.43**

151.1**

77.266**

5754.14

39.93**

Crosses

27

51.58**

91.45**

3955.1**

2607.50**

16.77

11.96**

8.45**

336.93**

7818.44**

16.10

Cross × E

54

10.20**

21.83**

1034.3**

491.15**

10.25**

8.12**

5.64**

40.17**

2401.72**

10.92**

GCA

6

110.44**

227.99**

9114.71

6886.81**

33.72

23.21**

8.53**

500.3**

17818.6**

43.88**

SCA

21

15.91

32.94

1743.70

773.51

9.51

29.32

8.43

290.25

3532.67

4.20

GCA × E

12

9.08**

21.94**

1300.10**

603.09**

15.02**

13.30**

102.2**

42.53**

2079.19**

17.64**

SCA × E

42

12.00**

21.78**

920.45**

443.17**

8.20**

9.11**

52.16**

12.43**

2539.94**

8.04**

Residuals

162

1.49

2.14

153.18**

149.30

3.33

2.705

11.671

42.341

545.21

1.96

*P ≤ 0.05, **P ≤ 0.01 and SV = Source of variation; DT = Days to Tasseling (50%), DS = Days to Silking (50%), PH = Plant Height (cm), EH = Ear Height (cm), EL = Ear Length (cm), ED = Ear Diameter (cm), R/C = Rows per Cob, S/R = Seeds per Row, TGW = Thousand Grains Weight (gm) and GY = Grain Yield (t/h).

 3.3. General Combining Ability (GCA) Effects 21 F<sub>1 </sub>Hybrids of Short Statured Maize Inbred Lines

Parents P1, P3 and P4 showed significant and negative GCA for days to pollen shedding and silking. For days to tasseling, negative estimates were considered desirable as those were observed to be associated with earliness. So, use of these four parents might be useful in developing early hybrid variety(s). [17] observed significant negative variances in case of two inbreds. [18] [19] observed the importance of additive genetic effects in controlling early maturity and yield.

Parents P2, P6 and P7 exhibited significant and negative GCA effect both for plant and ear height. So, use of these three parents might be useful in developing short statured hybrid variety(s). the characteristics of a line along with the behaviour shoould be considered in the production of hybrid maize [20] [21] mentioned that earliness was associated with days to silking and the shorter plants as well. For grain yield (t/ha), both parents P3, P4 and P7 showed significant and positive GCA effect. In addition to grain yield, parent P3 and P4 were also good general combiner, respectively, for thousand grain weight, ear length and ear diameter ( Table 3 ). Ear diameter, ear length, thousand seed weight were recorded as good general combiners in the study of [17] [22] [23] .

 3.4. Specific Combining Ability (SCA) Effects 21 F<sub>1 </sub>Hybrids of Short Statured Maize Inbred Lines

For grain yield (t/ha), the crosses P1 × P3, P4 × P5, P5 × P6 and P5X × P7 exhibited significant positive SCA effects. Significant and negative SCA effects for days to pollen shedding and silking are desirable for early maturing hybrids. Many of the crosses (P2 × P3, P2 × P4, P2 × P5, P4 × P5, P4 × P6, P4 × P7, P5 × P6 and P5 × P7) exhibited significant negative SCA effects for days to pollen shedding and silking. Four crosses (P1 × P5, P1 × P6, P2 × P6 and P3 × P4) exhibited significant and negative SCA effects for both plant and ear height and were desirable for exploiting non additive gene. In case of ear length, only one cross (P3 × P6), expressed significant and positive SCA effect. The cross (P2 × P7) exhibited positive and non-significant SCA effects. Four crosses (P3 × P7, P4 × P6, P5 × P6 and P5 × P7) showed significant and positive SCA effects for two major yield contributing characters; ear length and ear diameter ( Table 4 ).

Normally the GCA effects do reflect in the SCA effects of the crosses in most of the studied traits as stated in the findings of [22] [24] [25] . Good general combining parents may not show high SCA effects in their hybrid combinations [26] . However, [16] [27] observed high estimates of SCA from high GCA parents. [28] reported positive relationship between SCA effects of kernels yield and yield contributing characters [29] suggested that both additive and non additive effects are important in controlling the expression of grain yield and days to silking though on additive effects were more important in controlling grain yield than in determining days to silking in their studies. The SCA was more highlighted than the GCA in the studies of [30] .

<xref ref-type="bibr" rid="scirp.140357-"></xref>Table 3. Estimates of general combining ability effects (GCA) of the parents for yield and yield contributing characters of short statured maize inbred lines over three environments during rabi 2020-21.

Parents

DT (50%)

DS (50%)

EH (cm)

PH (cm)

EL (cm)

ED (cm)

R/C

S/R

TGW

GY (t/h)

P1

−0.3915*

−0.677*

0.9653

1.435

0.47*

0.33*

0.05

1.223*

3.66

−0.328**

P2

0.5344*

0.693*

−17.31**

−5.14**

−0.80**

−0.35*

−0.31*

−3.3**

1.45

−0.396**

P3

−0.91**

−0.973**

16.25**

10.977**

1.34**

1.00**

0.22

3.5**

19.93**

0.5535**

P4

−1.984**

−1.714**

18.93**

4.432**

0.73**

0.30*

0.59**

3.06**

5.476

0.61**

P5

0.942**

0.656*

2.51

0.446

−0.90**

−0.33*

−0.09

−1.31*

−11.61*

−0.042

P6

1.164**

1.545**

−16.07**

−7.85**

−1.09**

−0.89**

−0.24

−2.52**

−8.067

−0.654**

P7

0.6455**

0.471

−5.28*

−4.30**

0.23

−0.05

−0.22

0.65

8.84*

0.26**

SE (gi)

0.1546

0.2037

1.4793

0.8747

0.1559

0.1042

0.1019

0.449

3.3315

0.0661

LSD (0.05)

0.378

0.498

3.62

2.14

0.381

0.255

0.25

1.1

8.16

0.1617

LSD (0.01)

0.573

0.755

5.484

3.243

0.578

0.386

0.378

1.664

12.350

0.245

*P ≤ 0.05, **P ≤ 0.01; DT = Days to Tasseling (50%), DS = Days to Silking (50%), PH = Plant Height (cm), EH = Ear Height (cm), EL = Ear Length (cm), ED = Ear Diameter (cm), R/C = Rows per Cob, S/R = Seeds per Row, TGW = Thousand Grains Weight (gm) and GY = Grain Yield (t/h).

<xref ref-type="bibr" rid="scirp.140357-"></xref>Table 4. Specific combining ability effects (SCA) of 21 crosses for yield and yield contributing characters of short statured maize inbred lines over three environments during rabi 2020-21.

Crosses

DT (50%)

DS (50%)

EH (cm)

PH (cm)

EL (cm)

ED (cm)

R/C

S/R

TGW

GY (t/h)

P1 × P2

1.50**

0.806

−0.83

0.316

−1.41**

−0.48

0.08

−6.57**

16.07

0.31

P1 × P3

0.611

−0.194

9.58*

4.1

−0.09

−0.19

−0.34

−0.466

30.91*

2.72**

P1 × P4

−1.31**

−0.78

8.80*

9.57**

0.70

0.56*

−0.04

4.633

62.04**

−2.00**

P1 × P5

2.426**

2.51**

−31.97**

−17.54**

−0.68

−0.83**

−0.14

−3.663**

22.23

−0.23

P1 × P6

0.537

0.954

−14.07**

−5.41*

−0.89*

−0.28

0.01

−4.454**

23.80*

−0.68

P1 × P7

1.389**

0.361

−6.10

−7.20**

0.26

0.35

0.77**

−0.65

24.80*

−0.70

P2 × P3

−1.98**

−1.23*

22.29**

6.01*

0.16

0.46

1.91**

6.052**

51.47**

−0.60

P2 × P4

−1.91**

−1.49**

10.44**

5.32*

0.23

0.16

0.20

−0.85

4.14

0.205

P2 × P5

−0.833*

−1.86**

−8.05*

−2.70

0.19

0.19

−0.45

1.2

44.55**

0.25

P2 × P6

0.611

0.92

−7.83*

−6.30**

0.18

−0.27

1.03**

−2.602*

19.457

−1.045**

P2 × P7

1.463**

1.99**

−5.52

−6.25**

−1.00*

0.10

−0.98**

−3.8**

22.01

0.35

P3 × P4

−0.463

−0.491

−13.48**

−6.454**

−1.38**

0.27

−0.33

−6.97**

2.10

−0.645

P3 × P5

−1.39**

−1.53**

8.83*

5.421*

0.12

1.30**

0.35

−1.27

21.07

1.40**

P3 × P6

−0.611

−1.10*

27.18**

18.85**

0.23

0.81**

−0.83**

3.275**

25.864*

−1.64**

P3 × P7

−2.31**

−2.45**

26.58**

11.50**

0.99*

0.61*

−0.02

0.83

0.20

−0.644

P4 × P5

0.241

1.66**

9.623*

7.032**

1.46**

0.75**

0.49

6.2**

33.531**

3.05**

P4 × P6

−1.53**

−1.34*

−3.03

−7.30**

1.45**

0.90**

−0.54*

1.37

30.21*

−1.56**

P4 × P7

−1.68**

−1.93**

8.14*

4.143

−0.17

0.35

0.78**

0.51

41.54**

−1.71**

P5 × P6

−0.463

−0.64

6.68

6.148*

3.35**

0.93**

0.81**

4.1**

23.852*

1.00**

P5 × P7

−1.61**

−1.639**

57.93**

24.66**

4.36**

2.81**

0.80**

6.88**

26.85*

2.2**

P6 × P7

−0.5

−1.53**

−7.93*

−1.67

−1.12**

−0.50

0.28

−1.577

6.64

−0.53

SE (ij)

0.3827

0.5042

3.661

2.165

0.386

0.26

0.2521

1.1113

8.254

0.1636

LSD (0.05)

0.8

1.052

7.636

4.516

0.805

0.538

0.5258

2.32

23.6

0.84

LSD (0.01)

1.0888

1.434

10.415

6.16

1.1

0.734

0.717

3.1616

32.14

0.9654

*P ≤ 0.05, **P ≤ 0.01; DT = Days to Tasseling (50%), DS = Days to Silking (50%), PH = Plant Height (cm), EH = Ear Height (cm), EL = Ear Length (cm), ED = Ear Diameter (cm), R/C = Rows per Cob, S/R = Seeds per Row, TGW = Thousand Grains Weight (gm) and GY = Grain Yield (t/h).

 4. Conclusions

GCA effects showed wide range of variability among the parents. For all the characters none of the parents were found to be a good general combiner but P3 and P4 (CML33 and CML41) were found to be good general combiner for maximum characters. P3, P4 and P7 (CML33, CML41 and CML124) showed significant and positive GCA effect for grain yield, parents P3 and P4 (CML33 and CML41) were also good general combiner respectively, for thousand grain weights, ear length and ear dia. So, these two parents; P3 and P4 (CML33 and CML41) could be selected in hybrid breeding program with a view to increase the yield level.

Considering SCA the crosses; P1 × P3 (CML116 × CML33), P4 × P5 (CML41 × CML31), P5 × P6 (CML31 × CML32) and P5X × P7 (CML31 × CML124) exhibited significant and positive effects for grain yield (t/ha). These crosses involved both low × high and high × high general combining parents and produced significant positive SCA. Four crosses; P1 × P5 (CML116 × CML31), P1 × P6 (CML116 × CML32), P2 × P6 (CML72 × CML32) and P3 × P4 (CML33 × CML41), exhibited significant and negative SCA effects for both plant and ear height which are desirable for short stature. The crosses; P2 × P3 (CML72 × CML33), P2 × P4 (CML72 × CML41), P2 × P5 (CML72 × CML31), P4 × P5 (CML41 × CML31), P4 × P6 (CML41 × CML32), P4 × P7 (CML41 × CML124), P5 × P6 (CML31 × CML32) and P5 × P7 (CML31 × CML124) exhibited significant and negative SCA effects for days to pollen shedding and silking which are desirable for selection of early maturing hybrids. Two crosses; P4 × P5 (CML41 × CML31) and P1 × P3 (CML116 × CML33) exhibited maximum significant and positive SCA effects for grain yield (t/ha). P4 × P5 (CML33 × CML31) also showed standard heterosis over two checks at 1% level. These crosses need to be further evaluated in large plot and in wider agro-climatic conditions.

 References Bodker, L., Wulff, E. and Thorp, J. (2006) Seed Sector Country Profile: Bangladesh H. Volume I: Overview of Seed Supply Systems and Seed Health Issues. Copenhagen: Danish Seed Health Centre for Developing Countries. Rashid, H.A., Ali, M. and Gisselquist, D. (2012) Private-Sector Agricultural Research and Innovation in Bangladesh Overview, Impact and Policy Options. International Food Policy Research Institute. FAOSTAT (2012) Statistical Database of the Food and Agriculture of the United Nations. Baral, B. (2016) Agriculture Market Information System (AMIS) in Bangladesh. 26th Session on Asia and Pacific Commission on Agriculture Statistics, Thimphu, 15-19 February 2016, 1-35. Department of Agricultural Extension (2023) Dhaka, Bangladesh. Pavan, R. (2009) Gene Action and Combining Ability Studies in Single cross Hybrids of (Zea mays L.). M.S. Dissertation. University of Agricultural Sciences. Begum, S., Amiruzzaman, M., Matin, Q.I., Alam, S.S. and Rohman, M.M. (2016) Estimation of Combining Ability of Baby Corn (Zea mays L.) for Cob and Fodder Yield Using Line×Tester Design. Journal of Biology and Nature, 6, 181-188. Rojas, B.A. and Sprague, G.F. (1952) A Comparison of Variance Components in Corn Yield Trials: III. General and Specific Combining Ability and Their Interaction with Locations and Years. Agronomy Journal, 44, 462-466. >https://doi.org/10.2134/agronj1952.00021962004400090002x Fan, X.M., Tan, J., Yang, J.Y., Liu, F., Huang, B.H. and Huang, Y.X. (2002) Study on Combining Ability for Yield and Genetic Relationship between Exotic Tropical, Subtropical Maize Inbreeds and Domestic Temperate Maize Inbreeds. Scientia Agricultura Sinica, 35, 743-749. Melani, M.D. and Carena, M.J. (2005) Alternative Maize Heterotic Patterns for the Northern Corn Belt. Crop Science, 45, 2186-2194. >https://doi.org/10.2135/cropsci2004.0289 Barata, C. and Carena, M.J. (2006) Classification of North Dakota Maize Inbred Lines into Heterotic Groups Based on Molecular and Testcross Data. Euphytica, 151, 339-349. >https://doi.org/10.1007/s10681-006-9155-y Bello, O.B. and Olaoye, G. (2009) Combining Ability for Maize Grain Yield and Other Agronomic Characters in a Typical Southern Guinea Savanna Ecology of Nigeria. African Journal of Biotechnology, 11, 2518-2522. Akanda, M.A.L. (2001) Combing Ability of Yield and Yield Component in Maize. Bangladesh Journal of Agricultural Research, 26, 67-72. Russell, W.A. (1976) Genetic Effects and Genetic Effect×Year Interactions at Three Gene Loci in Sublines of a Maize Inbred Line. Canadian Journal of Genetics and Cytology, 18, 23-33. >https://doi.org/10.1139/g76-004 Alika, J.E. (1994) Diallel Analysis of Ear Morphological Characters in Maize (Zea mays L.). Indian Journal of Genetics and Plant Breeding, 54, 22-26. Vasal, S.K., Srinivasan, G., González, F.C., Beck, D.L. and Crossa, J. (1993) Heterosis and Combining Ability of Cimmyt’s Quality Protein Maize Germplasm: II. Subtropical. Crop Science, 33, 51-57. >https://doi.org/10.2135/cropsci1993.0011183x003300010007x Matin, M.Q.I., Rasul, M.G., Islam, A.K.M.A., Mian, M.A.K., Ivy, N.A. and Ahmed J.U. (2016) Combining Ability and Heterosis in Maize (Zea mays L.). American Journal of BioScience, 4, 84-90. >https://doi.org/10.11648/j.ajbio.20160406.12 Vasal, S.K., Srinivasan, G., Crossa, J. and Beck, D.L. (1992) Heterosis and Combining Ability of Cimmyt’s Subtropical and Temperate Early-Maturity Maize Germplasm. Crop Science, 32, 884-890. >https://doi.org/10.2135/cropsci1992.0011183x003200040010x Beck, D.L., Vasal, S.K. and Crossa, J. (1990) Heterosis and Combining Ability of CIMMYT’s Tropical Early and Intermediate Maturity Maize (Zea mays L.) Germplasm. Maydica, 35, 279-285. Malik, I. (2004) General and Specific Combining Ability Studies in Maize Diallel Crosses. International Journal of Agriculture and Biology, 6, 1-5. Singh, S.P. and Singh, H.N. (1979) Genetic Divergence in Okra (Abelmoschus esculentus L. Moerch). Indian Journal of Horticulture, 36, 166-170. Hussain, S.A., Amiruzzaman, M. and Hossain, Z. (2003) Combining Ability Estimates in Maize. Bangladesh Journal of Agricultural Research, 28, 435-440. Singh, G., Singh, M. and Dhiman, K.R. (1995) Genetic Analysis of Maize (Zea mays L.) in Sikkim. The Indian Journal of Agricultural Sciences, 65, 293-294. Debnath, S.C. and Sarker, K.R. (1987) Genetic Analysis of Grain Yield and Some of Its Attributes in Maize (Zea mays L.). Thai Journal of Agricultural Science, 20, 263-276. Paul, K.K. and Debnath, S.C. (1999) Heterosis and Combining Ability for Grain Yield and Its Components Exhibited Significant Positive Heterosis, The Highest in Maize (Zea mays L.). Bangladesh Journal of Agriculture, 24, 61-68. Deitos, A., Arnhold, E., Mora, F. and Miranda, G.V. (2006) Yield and Combining Ability of Maize Cultivars under Different Ecogeographic Conditions. Cropp Breeding and Applied Biotechnology, 6, 222-227. >https://doi.org/10.12702/1984-7033.v06n03a06 Paul, S.K. and Duara, R.K. (1991) Combining Ability Studies in Maize (Zea mays L.). International Journal of Tropical Agriculture, 9, 250-254. Das, U.R. and Islam, M.H. (1994) Combining Ability and Genetic Studies for Grain Yield and Its Components in Maize (Zea mays L.). Bangladesh Journal of Plant Breeding and Genetics, 7, 41-47. Crossa, J., Vasal, S.K. and Beck, D.L. (1990) Combining Ability Estimates of CIMMYT’s Tropical Yellow Maize Germplasm. Maydica, 35, 273-278. Sprague, G.F. and Tatum, L.A. (1942) General vs. Specific Combining Ability in Single Crosses of Corn. Agronomy Journal, 34, 923-932. >https://doi.org/10.2134/agronj1942.00021962003400100008x