Pak. J. Bot., 50(4): 1395-1405, 2018. GENETIC ANALYSIS FOR EARLINESS AND YIELD TRAITS IN MAIZE SARDAR ALI 1 , NAQIB ULLAH KHAN 2 , ROZINA GUL 2 , ISHRAT NAZ 3 , RABIA GOHER 4 , NAUSHAD ALI 1 , SHER ASLAM KHAN 1 , IJAZ HUSSAIN 1 , MUHAMMAD SAEED 1 AND MUHAMMAD SAEED 5 1 Department of Agricultural Sciences, University of Haripur, Haripur- Pakistan 2 Department of Plant Breeding and Genetics, The University of Agriculture, Peshawar - Pakistan 3 Department of Plant Pathology, The University of Agriculture, Peshawar - Pakistan 4 Department of Agronomy, The University of Agriculture, Peshawar – Pakistan 5 Department of Weed Science, The University of Agriculture, Peshawar, Pakistan Abstract Five white kernel maize inbred lines with distinct genetic make-up were crossed in a 5 × 5 complete diallel fashion during spring season 2011 at Cereal Crops Research Institute (CCRI), Pirsabak - Nowshera, Pakistan. The resulting 20 F1 hybrids, their five inbred lines and two checks hybrids (OPV 'Jalal' and 'Pioneer hybrid 30K08') were further evaluated during subsequent summer season 2011 at four locations. Present research was designed to study the genetic mechanisms controlling various earliness and yield traits through Hayman’s diallel approach. Genotypes, locations and genotype by environment interactions (GEI) showed significant (p≤0.01) differences for all the traits studied. Significant genotypic differences for various traits justified to carryout the Hayman's genetic analysis. For adequacy, the additive-dominance model was adequate / partially adequate for various traits at all the locations. According to genetic analysis, the key components of genetic variances i.e., additive (D) and dominance components (H1, H2) and average degree of dominance revealed that dominance components were predominant and overdominance type of gene action played an important role in the inheritance of all the traits at different locations. Genetic analysis further revealed unequal proportion of positive (U) and negative (V) alleles in the loci (H2<H1) with asymmetrical distribution of genes in the parental genotypes (H2/4H1 < 0.25) for majority of the traits. Broad sense heritability values were higher for days to 50% tasseling (0.89 to 0.97), days to 50% silking (0.91 to 0.97), ear length (0.86 to 0.99), 1000-grain weight (0.92 to 0.97) and grain yield (0.98 to 0.99), respectively at all the locations. Narrow sense heritability for above traits was low to medium ranging from 0.12 to 0.23, 0.17 to 0.33, 0.13 to 0.36, 0.10 to 0.51 and 0.07 to 0.11, respectively at all the locations. Desirable high genetic gain values were observed for yield traits while for earliness the values were moderate. Due to non-additive genes controlling various traits and high broad sense heritability estimates, the promising F1 hybrids could be developed in future breeding programs for production of early maturing and high yielding maize hybrids and cultivars through selection from later segregating generations. Key words: Diallel crosses, Additive dominance model, Components of genetic variances, Broad and narrow sense heritability, Genetic gain, Zea mays L. Introduction Maize (Zea mays L.) is an important cereal crop of the world grown in irrigated and rain-fed areas, and ranks third after wheat and rice (Gerpacio & Pingali, 2007). It is an annual short day plant and belongs to family poaceae and tribe Maydeae. Maize utilizes solar radiations more efficiently than other cereals. It is grown at an altitude of 3300 meters above sea level and from 50 0 N to 40 0 S latitude in temperate, sub-tropical and tropical regions of the world (Iqbal, 2009; Sajjad et al., 2016). Maize plant is monoecious and protandrous, and hot dry weather usually accelerates pollen shedding (Poehlman, 1977). It can be grown on all types of soils ranging from sandy loam to clay loam. However, medium texture soil of pH 6.5 to 7.5 is the most suitable for its successful cultivation. In Pakistan, maize is third important cereal crop after wheat and rice (Hussain et al., 2011). Maize is cultivated as multipurpose crop for food, feed and fodder by the farming community, who largely lives in rural areas. The use of maize in Pakistan as direct human food is decreasing; however its industrial use is increasing at a much faster rate. In Pakistan, maize was grown on an area of 1.334 million hectares and total production was 6.13 million tones with average grain yield of 4.595 tons ha -1 (PBS, 2016-17). In Khyber Pakhtunkhwa province of Pakistan, after wheat, the maize is the second important summer cereal with an area of 0.448 million hectares and production of 0.849 million tons with average grain yield of 1.896 tons ha -1 (BS-PDP, 2015-16). In Khyber Pakhtunkhwa, more than 27% of the total cultivated area is occupied by maize, with total cropped area of 42% (Iqbal et al., 2010). In the mountainous areas of Khyber Pakhtunkhwa, maize is utilized as an important staple food by the farming community as well as source of green and dry fodder for livestock (Iqbal et al., 2010; Khan et al., 2011). Production and evolution of high yielding and well- adopted cultivars with desirable characters is a continuous process and needs to understand in detail the genetic mechanism controlling yield and yield contributing traits (Saleem et al., 2002). Large numbers of breeding procedures have been developed to increase the economic yield of different maize populations and their hybrids. In order to select the prominent specific cross combination as hybrid, large number of selected inbred lines are crossed (Unay et al., 2004). Before starting the breeding program for the development of promising maize hybrids/cultivars, it is of utmost importance to assess the germplasm for earliness, morphological, and yield traits, and to study their genetic architecture, because exploitation of genetic variability in the germplasm of any crop species is considered the key point for making further genetic improvement in economically important traits. In maize, greater magnitude of genetic variability has been reported which indicates the potential for genetic improvement (Wattoo et al., 2009). To tailor a plant genotype with desirable combination of traits, comprehensive information