Combining ability analysis in maize (Zea mays L.) under high altitude temperate conditions of Kashmir

A.G.Rather¹, S.Najeeb, F.A.Sheikh* and A.B.Shikari* and Z.A.Dar

*Rice Research and Regional Station, SKUAST-K ,Khudwani

S K University of Agricultural Science and Technology of Kashmir

Abstract

Combining ability of 10 diverse maize lines and their 45 F1 crosses , generated through a half diallel matting system ,was assessed over two locations differing in climatic and edaphic conditions.. The variances due to gca and sca showed the importance of both additive and non additive gene effects in the inheritance of all the characters studied. Higher magnitude of gca variances for all the traits indicated the predominance of additive and additive type of gene action while for grain yield nearly equal importance of both additive and non additive gene effects was observed .Though additive and non additive gene effects were both highly influenced by environment for grain yield and maturity traits but for the former non additive effects were less susceptible to environmental variation. For other traits gca and sca effects were highly affected by environment except for plant height and ear placement were latter component interacted little with environment.The estimates of gca effects revealed that parents PMI-1, PMI-53, PMI 224 and PMI-401 were good general combiners for grain yield and for earliness.The crosses PMI-1 x PMI 224,PMI-47 xPMI-53, PMI-47 x PMI-224, PMI-83 x PMI-198, PMI-135 x PMI-401 and PMI-199 x PMI-401 were good for grain yield,earliness and lower moisture content.

Key words:Combining ability,maize,temperate conditions

Introduction

Globally,spectacular progress has been witnessed in the production and productivity of maize crop through the exploitation of hybrid vigour.Combining ability analysis assumes considerable importance as not all the lines yield superior hybrids upon hybridization. The frequencies of desirable inbred lines, in maize, has been placed between 0.1and 0.01 percent (Bauman,1981).Maize though widely considered as warm weather crop, is currently grown between 55⁰ north and south latitudes(Shaw,1988). However due to limited frost free season earliness assumes a considerable significance in tailoring maize cultivars suitable in high altitude areas. The present investigation was undertaken to characterize ten diverse lines and their 45 F1 cross combinations for their general and specific combining ability effects, respectively, and identify the potential hybrids for cultivation under temperate high altitude conditions of Kashmir.

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¹Present address: Professor, Division of Plant Breeding & Genetics Shalimar campus,SKUAST-K

Material & methods

Ten inbred lines namely,PMI-1,PMI-26,PMI-47,PMI-53,PMI-83,PMI-135,PMI-198,PMI-199,PMI-224 and PMI-401(designated as P₁ to P₁₀) were evaluated in a half diallel mating design to generate 45 F₁ crosses.The parents and their crosses were evaluated at two locations vizHigh Altitude Maize Research Sub Station,Pahalgam(2222m asl;341/2⁰N,741/2⁰E) and Regional Research station Khudwani(1542m asl;341/2⁰N,741/2⁰E)of Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir,India during Kharif 2005.The experimental material was arranged in a randomized complete block design with three replications per location. Lines and crosses were randomized separately in each experiment. Each entry was represented by two rows of 4m length with a crop geometry of 60 x 20cm having a plant density of 83333 plants per hectare. The data were recorded for six quantitative traits (Table-1).Grain yield was calculated using fresh ear weight at harvest, assuming 80% shelling and adjusted to 15% moisture content. Ear height was recorded for the primary ear. Combining ability analysis was performed using Griffings1956) method 2 model II. Pooled analysis over environments was carried out following Singh (1973b,1979)

Results &Discussions

Pooled analysis of variance for combining ability (Table 1) revealed the presence of highly significance of mean squares due to GCA and SCA for all the characters studied indicating thereby the differences among parental lines for GCA and among crosses for SCA effects. The diversity of test locations was revealed by their highly significant mean squares. Both GCA and SCA effects showed significant interaction with location for all the traits. This suggested the differential response of lines and crosses for GCA and SCA effects respectively implying thereby that different parental lines are needed to synthesize hybrids for different ecological situations. The SCA effects for grain yield , 50% silking, plant height and ear placement were relatively stable over locations as indicated by lower estimates of SCA x location interaction, whereas reverse was the case for days to pollen shed and moisture content.

The ratio of estimated GCA to SCA variances indicated the preponderance of the latter component in controlling the expression of all the traits. The SCA variances involves both dominance and epistasis which together constitute the non additive type of gene action, whereas the GCA variance is a reflection of additive and additive x additive type of gene action.The non additive component of gene action could be optimized in upgrading the genetic potential of the crop by adopting reciprocal recurrent selection and hybrid technology, which has already become a field reality in maize.

The perusal of GCA effects(Table 2) reveals that P₁₀ was an ideal general combiner for all characters followed by P₁,whereas P₉ was a good general combiner for all traits except pollen shed.P₄ though a good combiner for grain yield showed positive significant GCA effects for moisture content and plant height. The estimates of SCA effects of top ranking 12 crosses are presented in Table 3. P₈ xP₉ could be regarded as the most desirable cross combination closely followed by P₆ xP₁₀ and P₈ xP₁₀. An important inference that can be drawn from these results is that cross combinations involving P₁₀ as one of the parents recorded desirable SCA effects for all or most of the traits studied.

Since breeders working under high altitude conditions are confronted with seasonal limitations , earliness, therefore, is ranked second to yield in the primary breeding objectives. Further rapid dry down at maturity is receiving increased emphasis to promote early harvest, particularly when the cold sets in early in the growing season. The early harvest curtion helps reduce the risk of terminal frost damage and also allows some flexibility in planting time. After yield and maturity ,resistance to lodging is probably the next most important factor in the choice of a cultivar. P₁₀ thus could serve as a potential donor for all these desirable attributes and, therefore has a special value in the maize improvement programme of high altitude temperate ecology of Kashmir.

References

Bauman,L.f.1981.Review of methods used by breeders to develop superior corn inbreds.Proc.Annu.Corn sorghum Int.Res.conf.36:191-208.

Sing, D 1973 b. Diallel analysis for combining ability over several environments II. Indian J.Genet.,33:469-81.

Singh,D 1979.Diallel analysis for combining ability over environments. Indian J.Genet.,39:383-386

Griffing 1956.Concept of gca & sca in relation to diallel crossing system.Australian J.BMiol.Sci.,9:463-493.

Mather R K and Bhatnagar S.K.1995. Partial diallel cross analysis for grain yield and its component characters in maize (Zea mays L). Ann.Agric.Res.,16:324-329.

Subha Rao M.1992. Genetic studies on drought tolerance in maize (Zea mays L).Unpubl.Ph.D.Thesis, P.G.School,IARI,New Delhi.

Shaw,R.H 1988. Climate requirement.In Sprague,G.F.,Dudly,J.W,eds.corn and corn improvement,3^rd ed Madism, WI:ASA 609-638

Shreenivasa A.Desai and Singh R.D.2001.Combining ability studies for some morph physiological and biochemical traits related to drought tolerance in maize (Zea mays L).Indian J.Genet.61:34-36.

Vinod Kumar 1996.Genetic studies on yield, yield components and some morph physiological traits associated with drought tolerance in maize(Zea mays L).Ph.D Thesis, P.G.School,Indian agricultural Research Institute,New Delhi.

Joshi V.Ni,Pandiya,N.K and Dubey R.B.1998. Heterosis and combining ability for quality and yield in early maturing single cross hybrids of maize(Zea mays L). Indian J.Genet.,58:519-524

Table -1:Pooled analysis of variances for different traits in a diallel cross of maize

Source of variation	Df	Grain yield per plot (Kg)	Days to 50% pollen shedding	Days to 50% silking	Moisture content(%)	Plant height(cm)	Ear placement (cm)
	Mean squares
Locations	1	0.76**	0.13**	0.13**	0.22**	0.49**	0.44**
GCA	9	0.87**	0.75**	0.44**	0.32**	0.70**	0.89**
SCA	45	0.86**	0.18**	0.19**	0.24*	0.45**	0.58**
GCA x Locations	9	0.66**	0.28**	0.87**	0.30**	0.46**	0.38**
SCA x Locationst	45	0.13	0.30**	0.30**	0.45**	0.14	0.11
Pooled error	108	0.18	0.05	0.04	0.08	0.13	0.14
σ^2s/ σ^2g		0.021	0.353	0.127	0.065	0.080	0.075

*,** significant at 5% & !% level respectively

Table- 2: Estimates of GCA effects for different traits of inbred lines in maize

Parents	Pedigree	Grain yield	Pollen shed	Silking	Moisture content	Plant height	Ear placement
1	PMI-1	0.29*	-1.56*	-1.64**	-0.22*	-0.14	-4.77**
2	PMI-26	-0.03	-0.45**	-0.12	-0.76**	4.27**	-6.69**
3	PMI-47	-0.04	0.06	0.35**	0.44**	6.04**	5.74**
4	PMI-53	0.26*	-0.10	-0.56**	0.19*	1.98**	-0.70**
5	PMI-83	-0.14	-0.21*	1.14**	-0.11	-1.01**	4.97**
6	PMI-135	-0.02	-1.37**	-0.97**	-0.05	8.56**	2.35**
7	PMI-198	0.05	1.76**	-1.64**	0.58**	1.62**	-3.98**
8	PMI-199	0.10	2.14**	1.43**	-0.16*	10.46**	1.66**
9	PMI-224	0.25*	-0.02	-0.81**	-0.66**	15.02**	9.64**
10	PMI-401	0.43**	-4.00**	-2.41**	-1.48**	-34.37**	-9.62**
SE gi		0.11	0.06	0.05	0.08	0.10	0.10
SEgi-gj		0.17	0.09	0.08	0.13	0.15	0.15

*,** significant at 5% & !% level respectively

Table- 3 : Estimates of SCA effects of selected crosses in maize

Cross	Grain yield	Pollen shed	Silking	Moisture content	Plant height	Ear placement
1x5	0.31*	1.16**	1.10*	-0.39*	32.34**	0.27
1x9	0.34*	-2.22**	-1.65**	-1.74**	22.3**	16.8**
2x6	0.32*	-0.85**	0.10	0.28*	14.78**	6.51**
3x4	0.42*	-2.35**	-3.13**	-0.29*	35.85**	-4.27**
3x9	0.37*	-1.80**	-3.12**	-2.49**	32.00**	7.79**
4x8	0.35*	-1.68**	1.56**	-2.63**	15.23**	-0.20
4x10	0.53**	6.53**	2.06**	-0.30**	-21.57**	-11.85**
5x7	0.34*	-1.12**	-1.82**	0.33**	-4.07**	0.38**
5x8	0.31*	-0.25**	0.20*	-0.90**	11.48**	13.03**
6x10	0.46**	-1.80**	-1.25**	-2.03**	-2.05**	-2.29**
8x9	0.54**	-1.35**	-1.59**	-4.49**	-5.3**	-20.07**
8x10	0.30*	-0.24**	2.59**	-3.68**	5.55**	-1.91**
SE Sij	0.16	0.07	0.08	0.10	0.13	0.14
SE(Sij-Skl)	0.55	0.26	0.29	0.37	0.47	0.48

*,** significant at 5% & !% level respectively