Maize (Zea mays L) is third most important cereal crop in the world, agricultural economy and is a rel¬evant source of food, feed and industrial products. In India maize ranks fifth position in area and fourth in production among the major cereals grown. Being a C4 plant and having very high yield potential, it is called queen of cereals. One of the main deterrents to high grain yield in maize is its susceptibility to several diseases.

Of 112 diseases of maize reported so far from dif­ferent parts of the globe, 65 are known to occur in India Maize (Zea mays L). It is grown from 58⁰N latitude without interruption through the temperate, subtropical and tropical regions of the world to 40⁰S latitude, covering regions with rainfall varying from 250 to 1000 mm per annum (Hallauer and Miranda, 1988). Mainly, it is a crop of tropical and subtropical areas but can be cultivated successfully under temperate climate conditions, such as in dry temperate region of Himachal Pradesh. Maize grains and stalk are used for food, feed, fodder and even fuel. Apart from domestic consumption, it also provides raw materials for the production of several industrial products.

Maize (Zea mays L.) is one of the most important Kharif cereal crops of Himachal Pradesh. It is mainly used as food, feed and fodder in the state and is grown over a wide range of agro-climatic conditions. Diseases are an important constraint for maize production in the state. Among the various diseases of maize, turcicum leaf blight & brown spot diseases are widely prevalent indifferent maize growing areas of the state. During the recent past the spread of different maize hybrids in the state has increased the incidence of different diseases. Hence, the present study was undertaken to identify the hybrids against leaf blight and brown spot diseases of maize.

Results and Discussion
The parent and hybrids of maize in present investigation were also evaluated under natural epiphytotic conditions during 2004 and 2005 for reaction to leaf blight (Helminthosporium maydis and H. turcicum) and brown spot (physoderma zea maydis) (Table 1).
  

The parents viz., line-2, 4, 6, 7, 9, 12, 14, 15, 16 were observed light infection during 2004 and 2005; line-1, 4, 5, 6, 7, 11, 12, 13, 20, 21, 24 showed light infection for brown spot diseases. Remaining lines did not behave consistently during 2004 and 2005 for slight or light infection in respect to diseases for leaf blight or brown spot vice-versa.

Cross combinations resistant to leaf blight
The cross combinations viz., Line-1×Early composite, Line-3×Early composite, Line-5×Early composite, Line-7×Early composite, Line-10×Early com- posite, Line-13×Early composite, Line-15×Early compo- site, Line-19×Early composite, Line-24×Early composite, Line-5×Girija, Line-11×Girija, Line-14×Girija, Line-15×Girija, Line-23×Girija, Line-4×KH-2001, Line-5×KH- 2001, Line-8×KH-2001, Line-18×KH-2001 and Line-19×KH-2001  showed resistant for leaf blight during 2004 and 2005. Similar results were also reported for leaf blight by Ishfaq et al. (2014).

Cross combinations resistant to brown spot

The cross combinations were observed resistant for brown spot viz., Line-3×Early composite, Line-4×Early composite, Line-5×Early composite, Line-10×Early composite, Line-13×Early composite, Line-19×Early composite, Line-20×Early composite, Line-2×Girija, Line-7×Girija, Line-10×Girija, Line-18×Girija, Line-19×Girija, Line-1×KH-2001, Line-5×KH-2001, Line-6×KH-2001, Line-18×KH-2001 and Line-19×KH-2001  during  kharif 2004 and 2005.

Cross combinations moderately resistant to leaf blight
The cross combinations viz., Line-2×Early com- posite, Line-9×Early composite, Line-11×Early composite, Line-14×Early composite, Line-23× Early composite, Line-1×Girija, Line-4×Girija, Line-7×Girija, Line-10×Girija, Line-12×Girija, Line-19× Girija, Line-21×Girija, Line-22×Girija, Line-1×KH-2001, Line-2×KH-2001, Line-7×KH-2001, Line-10×KH-2001, Line-12×KH-2001, Line-14×KH-2001, Line-15×KH-2001, Line-20×KH-2001, Line-22×KH-2001 exhibited moderate resistant for leaf blight during 2004 as well as 2005. Similar results were reported by Kumar and Singh (2002) and Garg et al. (2007).

Cross combinations moderately resistant to brown spot
The cross combinations revealed moderate resi- stant for brown spot viz., Line-6×Early composite, Line-12×Early composite, Line-14×Early composite, Line-16×Early composite, Line-3×Girija, Line-5×Girija, Line-6×Girija, Line-9×Girija, Line-11× Girija, Line-13×Girija, Line-17×Girija, Line-20× Girija, Line-22×Girija, Line-4×KH-2001, Line-8× KH-2001, Line-12×KH-2001, Line-14×KH-2001, Line-22×KH-2001 during 2004 as well as 2005.

Cross combinations moderately resistant to leaf blight & brown spot diseases
The cross combinations viz., Line-20×Early com- posite, Line-6×Girija, Line-13×Girija, Line-20×Girija, Line-12×KH-2001, Line-13×KH-2001, Line-21×KH-2001, Line-23×KH-2001 presented moderate infection for leaf blight and  Line-24×Girija, Line-10×KH-2001 for brown spot disease, during 2004 and 2005. Similar results were also reported by Sharma et al. (2002), Yang et al. (2005) and Bhavana and Gadag (2009).

Parents & cross combinations showed consistent performance in both the years
Among the parents used in the present study, four lines viz., Line-3, 8, 10, 18 showed resistance for leaf blight as well as brown spot diseases, whereas moderate resistance for these diseases was observed in Lines-4, 6, 7, 12, 16 under natural conditions during both the years. Therefore these lines should be used in hybridization programmes for generating moderate resistant hybrids. Four cross combinations viz., Line-14×Early Composite, Line-22×Girija, Line-14×KH-2001 and Line-22×KH-2001 showed moderate resistance for leaf blight and brown spot during the year 2004 as well as 2005.

The ten cross combinations Line-3×Early Composite, Line-5×Early Composite, Line-10×Early Composite, Line-13×Early Composite, Line-15×Early Composite, Line-19×Early Composite, Line-18×Girija, Line-5× KH-2001, Line-18×KH-2001 and Line-19×KH-2001 showed resistance for leaf blight and brown spot in both the years along with desirable specific combining ability for some of the traits under studied (Table 2). These hybrids thus appear to be suitable for cultivation in maize growing areas of Himachal Pradesh where blight and brown spot are the prominent diseases. Earlier worker, (Katna, 2000) has reported that severity of leaf blight as well as brown spot diseases was slightly more under Palampur condition than that at Bajaura, perhaps due to scanty rains received at location like Bajaura (Kullu). 
 

Hence it was concluded from the present study that the cross combinations, Line-13×Early Composite and Line-19×KH-2001 showed resistance against leaf blight and spot disease of maize with desirable high specific combining ability (SCA) effects for majority of traits in both the years under studied. Therefore theses cross combinations recommended for involving in crop improvement programmes.

Materials and Methods
Twenty four inbred lines (S-5 stage), derived from local germplasm collected from different parts of Himachal Pradesh were involved with three broad based testers, viz., Early composite, Girija composite and KH-2001(hybrids) in a line×tester fashion. The experimental material, comprising one hundred entries (72 crosses, 27 parents and one standard check, PMZ-4), was evaluated during kharif 2004 and 2005 in a simple lattice design with two replications at the Experimental Farm of Seed Production Unit, CSK HPKV, Palampur. Each plot consisted of 5 rows of 4 meters length with inter and intra row spacing of 60 and 15cm, respectively. Experiments were conducted under rainfed conditions following the recommended agronomic practices.  The data were recorded for leaf blight and brown spot as per Scale used 0-5 (Chenulu and Hora, 1962).

References
Bhavana P. and Gadag R. N., 2009, Evaluation of maize genotypes for resistance to banded leaf and sheath blight, Annals of Plant Protect Science 17: 498- 499

Chenulu W., and Hora T.S., 1962, Studies on losses due to Helminthosporium blight of maize, Indian Phytopathology 15:235-237

Garg A., Prassana B.M., Sharma R.C., Rathore R.S., Sax­ena S.C., Chauhan S.V.S., 2007, Identification of re­sistance source to banded leaf and sheath blight (Rhizoctonia solani F. sp sasakii) in maize, Indian Phytopathology 60: 162-166

Hallauer A.R., and Miranda J.B., 1988, Quantitative Genetics in Maize Breeding, 2nd ed., Iowa State University Press, Ames, IA, USA

Ishfaq A., Dar Z.A., ., Lone A. A.,  Ali G.,  Gazal A.,  Hamid B.,  and Mohiddin F.A., 2014, Disease reaction studies of maize against turcium leaf blight involving indigenous cytosterile source,  African Journal of Microbiological Research, 8(27):  2592-2597
http://dx.doi.org/10.5897/AJMR2014.6708   

Katna G., 2000, Combining ability, gene action and heterosis for some seed quality and yield parameters in maize (Zea mays L) PhD thesis submitted to CSKHPKV, Palampur (HP), India

Kumar R., and Singh I.S., 2002, Inheritance of resistance to banded leaf and sheath blight (Rhizoctonia so­lani F. sp sasakii) of maize (Zea mays L), Proceedings of the 8th Asian Regional Maize Workshop, pp 356- 365 Bangkok, Thailand

Sharma R.C., Vasal S.K., Gonzalez F., Batsa  B.K., Singh N.N., 2002,  Redressal of banded leaf and sheath blight of maize through breeding, Chemical and Bio control agents, pp. 391-397, In: Proceed of the 8th Asian Regional Maize Workshop: New Tech­nologies for the New Millennium, Bangkok 

Yang J.P., Tang  H.T., Yang J.X., Li  X.,  Chen D.Q., Zhang B., Shi Y.G., Huang Y.X., 2005,  Identification and inheritance of resistance of maize germplasm to sheath blight (Rhizoctonia solani) , Acta Phyto­pathologica Sinica 35: 174-178