Heterosis Beeding for Maturity, Yield and Quality Characters in Maize (Zea mays L.)  

Netra Hiremath1 , G. Shantakumar1 , Sateesh Adiger1 , Laxman malkannavar2 , Prakash Gangashetty1
1 Department of Genetics and Plant Breeding, college of agriculture, UAS Dharwad, India
2 Department of Genetics and Plant Breeding, GKVK, UAS Bangalore, India
Author    Correspondence author
Molecular Plant Breeding, 2013, Vol. 4, No. 6   doi: 10.5376/mpb.2013.04.0006
Received: 18 Jan., 2013    Accepted: 22 Jan., 2013    Published: 30 Jan., 2013
© 2013 BioPublisher Publishing Platform
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Netra H., et al., 2013, Heterosis Breeding for Maturity, Yield and Quality Characters in Maize (Zea mays L.), Molecular Plant Breeding, Vol.4, No.6 44-49 (doi: 10.5376/mpb.2013.04.0006)

Abstract

The utility of diallel crosses for identification superior combinations is a common in maize breeding programme. This methodology allows the estimation of combining ability of the parents being evaluated also extent of heterosis in respect to maturity, grain yield and quality traits. The experiment conducted using fourteen newly developed inbred and crossed in half diallel mating design (excluding reciprocals) during summer 2011 at MARS, Dharwad and developed 91 crosses. Ninety one F1 crosses of maize derived by diallel mating design involving fourteen inbred lines (excluding reciprocals) were studied to investigate heterosis over best check NK 6240 for maturity characters, yield characters and quality parameters. The crosses, 13x6, 7x6, 9x6 and 13x7 showed desirable heterosis for earliness i.e for days to 50% tasseling and for 50 % maturity. For the character grain yield per plant, crosses, 9x5, 10x7, 4x3, 8x7 and 14x10 showed significant heterosis over better parent and standard check in positive direction, these better performing crosses/hybrids can be exploited for exploiting hybrid vigour. Crosses, 10x3, 10x9, 11x10 and 10x3, 9x3, 7x3 showed heteosis in favourable direction over better parent and standard check.

Keywords
Maize (Zea mays L.); Diallel cross; Standard heterosis; Heterobeltosis; Inbred lines
Maize (Zea mays L.; 2n=20) is the second most important cereal of the world after wheat. By origin, maize is native to South America and it is a tropical crop and has adopted magnificently to temperate environments with much higher productivity. Maize is an important cereal crop belonging to tribe Maydeae of the grass family, Poaceae. Tribe Maydeae comprises eight genera, five of which areOriental (Coix, Schlerachne, Polytoca, Chinonachne and Trilobachene) and are relativelyunimportant. They are native to an area extending from India to Burma through East Indiesand into Australia. The three American genera are Zea, Tripsacum and Euchalaena. Euchalaena (teosinte), which appears to be the closest wild relative of maize, occursin Mexico and Guatemala. The annual form has 10 pairs of chromosomes like maize and isthe most common type. Perennial teosinte has 20 pairs of chromosomes and is found in arestricted area in Mexico. The annual form is used as a forage plant. The US has the largest harvested area of corn and contribution one fifth of the world corn harvested area. China, Maxico, India, Brazil and Indonesia are other countries which contribute significantly to world harvested area. These six countries have around 60 per cent of world corn production. Corn plays a significant role in human, livestock nutrition and a source of large number of industrial products world wide. Due to high yield potentiality, versatile uses, almost year round growth ability and higher per acre yield than other cereals, area and production of maize is increasing day by day in our country. Hybrid maize cultivation is also becoming popular among the farmers. The phenol- menon of heterosis for hybrid breeding has been commercially exploited in cross pollinated crops like maize, sunflower, pearl millet and sorghum. Maize is a highly cross pollinated crop and hand emasculation (detasseling) and wind borne pollination is used to produce hybrid seeds on a commercial scale. The cost of hybrid seeds at commercial scale is comparatively low due to higher rate of successful seed setting and large number of grains per ear. Heterosis is also e in deciding the direction of future breeding programme and to identify the cross combinations which are promising for hybrid breeding programme. In the present study, heterosis over better parent as well as standard check (NK 6240) were estimated for grain yield, maturity characters and quality parameters.

 

Results and Discussion
Exploitation of heterosis or hybrid vigour is an important method of crop improvement adopted in many of the crops especially in cross pollinated crops. This phenomenon of heterosis was attracted the attention of plant breeders due to its conspicuous effect on economic characters especially grain yield and also maturity, quality traits. This heterosis has been successfully exploited in many cross pollinated crops among which maize is the major one.

 

Maturity is an important attribute of a given genotype, which directly or indirectly affects economic yield. Maturity itself is expressed by several components such as days to 50% tasseling, days to maturity etc. For maturity characters like days to 50% tasseling, fourty two and eighteen crosses and days to 50% maturity thirty five and twenty nine crosses showed significant heterosis over better parent and standard heterosis exhibited significant heterosis in desirable direction (Table 1), for days to 50%tasseling heterosis ranged from -7.94% to 3.23% over better parent and -7.94% to 3.17% over standard check, for days to 50% maturity is ranged from -6.32% to 5.38% over better parent -4.30% to 5.38% standard Heterosis. Of these, 5×2, 12×2 , 5×4 for days to 50% tasseling and 14×4, 6×5, 11×10 for 50% maturity were may be the desirable crosses showed significant heterosis over mid parent and standard check (NK 6240). And totally thirteen crosses showed significant heterosis for both 50% tasseling and 50% maturity, among them 13×6, 7×6, 9×6 and 13×7 recorded the highest significant heterosis for earliness. This is in confirmation with the reports of Kalsy and Sharma (1970) and Murthy et al (1981), For yield characters, twenty seven crosses and five crosses exhibited significant heterosis over better parent and standard check, respectively. Those crosses, which exhibited signify-cant heterosis, it is suggested that these hybrids will serve as useful genetic material for development of early parents by selection in advanced generations.

 
Table 1 Per cent heterosis over better parent and standard check (NK 6240) for maturity, yield and quality characters in maize

Hundred grain weight is one of the important grain characters. Grains, the ultimate economic product from the maize plant are the net result of various components. The total yield in maize is influenced by several grain component characters. Ultimate grain yield of a plant depends mainly on 100 grain weight through various other component characters. The study of hundred-grain weight deserves much often attention because grain yield is product of action and interaction of various grain components and is expressed through changes in its components. So, improvement in these individual component characters will be quite easier and its study will help in understanding the complex metric trait, grain yield. For the character test weight, and teterosis ranges from –19.12% to 35.31% for better parent and from –18.11% to 16.91% for standard check. Among these crosses, 9×4, 13×2 and 4×3 were top three desirable crosses showed the significant heterosis in positive direction over better parent as well as standard check.
Grain yield per plant is the important yield characters. Grain yield is a complex quantitative character which is influenced by other ancillary and component characters. Hence all changes in the components would not be expressed as changes in yield but all changes in yield would be accompanied by changes in one or more components. For the character, grain yield per plant seventy six and five crosses showed the significant heterosis over better parent and standard check, respectively. The magnitude of heterosis ranged from -4.48% to 87.29% better parent and –31.58% to 22.11% for standard check. The crosses, 9×5, 10×7, 4×3, 8×7 and 14×10 were found to be desirable crosses and these also recorded significant heterosis over better parent as well as over standard check. The present work is in agreement with previous findings of Nagesh Kumar et al (1999), Devi and Prodhan (2004) and Unay et al (2004). Starch and protein are two important constituents of grain yield and these are very complex characters, which are influenced by other important characters, mainly yield and its attributes. So, comprehensive study becomes very different.
For quality parameters like for protein content, forty and twenty two crosses and for starch content fourty six and nineteen showed significant Heterosis in favourable direction, heterosis ranged from -36.62% to 32.39% for better parent and -40.41% to 27.69% over standard check for protein content and for starch content Heterosis ranged from -5.09% to 9.73 % and -6.01% to 3.55 % over standard check. The crosses, 10×3, 10×9, 11×10 and 10×3, 9×3, 7×3 were found to be desirable crosses both over better parent and standard check with respect to protein and starch content, respectively. Similar findings were also obtained Krishnaveni (1983) and Lal et al(2011). So one can go for hybrid development is the only way of attaining high grain yield per plant.
It is clear from the above discussion that three crosses, 5×2, 12×2, 5×4 for days to 50% tasseling and 14×4, 6×5, 11×10 for 50% maturity were found to best crosses for earliness. Crosses, ×5, 10×7, 4×3, 8×7 and 14×10 can be exploited commercially for grain yield per pant. For protein and starch content, crosses 10×3, 10×9, 11×10 and 10×3, 9×3, 7×3, respectively, can be exploited for improvement of these desirable quality characters. It is worth while to take up trails on farmers field to study the performance of this potential crosses, so as to make commercial exploitation of hybrid vigour a reality and also these Promising single cross hybrids for maturity, grain yield characters and quality parameters may be used for further improvement of lines by selection in advanced generations.
Material and Methods
The present investigation was carried out to study heterosis in maize. The experimental material comprised of fourteen newly developed inbred lines viz., DMIL 1,DMIL 2, DMIL 3, DMIL 4, DMIL 5, DMIL 6, DMIL 7, DMIL 8, DMIL 9, DMIL 10, DMIL 11, DMIL 12, DMIL 13 and DMIL 14 and hybrids generated by crossing the above inbreds in all possible combinations excluding reciprocals. The fourteen parents and 91 crosses were risen in lattice square design with two replications at maize scheme, MARS, University of Agricultural Sciences, Dharwad during kharif 2010-2011. All the management practices were followed as per recommendations. So as to rise a normal crop. Observations were recorded on five randomly selected plants of each treatment in two replications for six characters viz., days to 50% tasseling, days to 50% maturity, test weight (g), grain yield per plant (g), protein content (%) and starch content (%).
Authors' contributions
The author conducted the major part of this study including experimental design, data analysis and manuscript preparation. Netravati and G shanthakumar participated in experimental design and preliminary analysis of data. Prakash Gangashetty and Laxman Malkannavar carried out statistical analysis. Sateesh Adiger did final data analysis, tables and manuscript preparation. All authors read and approved the final manuscript.
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