INTRODUCTION Maize (Zea mays L.) is the third most important crop in India after rice and wheat and is cultivated round the year and grain is used as feed, food and industrial raw material. Maize production in India has increased more than 16 times from a mere 2 million tons in 1949-50 to 31.65 million tons in and presently it occupies 9.89 million hectare area with the mean yield of 3.19 tons/hectare (IndiaAgriStat.com) contributing to 9% of the Indian food basket. This achievement is remarkable despites ~75% maize is grown under rainfed and low input conditions in the country. It is being estimated that the demand for maize will continue to increase in view of increasing demand in poultry and livestock sectors in the country and growing non-vegetarian population and changing food habits. To meet the growing demand, enhancement of maize yield in coming years across all the growing locations in India is the big challenge in the era of climate change. Landraces are domesticated local varieties that have not developed through modern plant breeding programmes unlike cultivars. Landraces can be distinguished by specific morphological traits and had shown wide adaptability to biotic and abiotic stresses. They can constitute variable populations where variation can be observed between and within populations (Zeven, 1998). In the global maize germplasm no dearth of favorable alleles was observed for improvement of yield, abiotic stress tolerance, disease resistance or nutritional quality. However, these desirable alleles are often scattered over a wide array of landraces or populations and there is a need to highlight the enormous genetic diversity found in maize, especially in the landraces and the wild relative, teosinte and novel and systematic initiatives has to be undertaken to understand and for utilization in the breeding programmes to develop biotic and abiotic stress resistant inbreds/hybrids (Bhupender et al., 2019). Combining ability analysis is of special importance in cross-pollinated crops like maize as it helps in identifying potential parents that can be used for producing hybrids and synthetics. The nature and magnitude of gene action is an important factor in developing an effective breeding program, which can be understood through combining ability analysis. Therefore, the present study was carried out to develop top crosses involving land races to estimate combining ability and to unravel the gene action governing yield and its components and drought tolerant traits. MATERIALS AND METHODS The present study comprised of fifteen diverse maize germplasm lines viz. IC623875, IC636977, IC623877, IC623873, IC611611, IC611609, IC636965, IC 627707, IC 623879, IC611615, IC 623878, IC623880, IC627704, IC 627708 and IC 627705 collected from NBPGR, Hyderabad. These lines were crossed with three testers (BML-6, BML-7 and KML-109) in line × tester mating design during kharif, 2021. The resultant 45 F1 hybrids along with parents and five checks [Karimnagar makka, DHM 117, KMH-25K45, Bio-9544 and NK 6240] were evaluated in RBD in the field with three replications at ARS, Karimnagar during Rabi, 2021-22. Each entry was planted in two rows of 3 m length by following a spacing of 60 cm between rows and 20 cm between plants to plant. All the recommended agronomic package of practices was followed to raise a good crop. Data on fifteen quantitative characters i.e. plant height, ear height, ear length, ear girth, number of kernel rows and number of kernels per row, test weight (g) shelling percentage, SPAD chlorophyll content and stay green character were recorded on five randomly selected competitive plants in each replication while, days to 50 percent tasseling, days to 50 percent silking, anthesis-silking interval, days to maturity, and grain yield (kg/ha) and were recorded on plot basis. RESULTS AND DISCUSSION ANOVA (Table 1) revealed significant genetic differences among the genotypes for all the quantitative traits under study which is a prerequisite for any crop improvement. Variance due to hybrids and parents were highly significant for all the studied traits except Anthesis – Silking Interval (ASI) indicating the manifestation of parental genetic variability in their crosses. Mean squares for parents Vs crosses were highly significant (at the 0.01 level of probability) for all the characters indicating the presence of heterosis and heterotic effects. The mean squares for hybrids were partitioned into three components viz., due to lines, due to testers and due to line × tester interactions and differences among hybrids due to lines were significant for days to maturity only and due to testers and line × tester interactions were significant for flowering and maturity traits, plant height, ear height, ear diameter, 100 kernel weight and grain yield. This suggested that testers and crosses are variable for morphological, yield and yield contributing traits and gca and sca played a significant role in the genetic expression of these traits. Non significant differences were observed in case of lines for all the traits except days to maturity. Although variation is non significant in lines i.e. maize land races crosses had shown significant variation for all the traits. This could be due to complimentary gene action of alleles at individual loci resulting in over dominance either in positive or negative or both the directions. Proportion of sca variance was higher than gca variance indicating possibility of exploitation of hybrids and preponderance of non additive gene action in governing the traits. Similar results were reported by Oppong Allen et al. (2019). The estimates of GCA effects (Table 2) revealed that the lines IC 611611, IC 623875 and IC 624877 were good general combiners for grain yield. Line IC611611 was also a good general combiner for ear length, ear girth, number of kernel rows, number of kernels per row and 100 kernels weight apart from grain yield. For flowering and maturity traits six lines viz. IC 627704, IC 623880, IC 623878, IC 623879, IC 627707 and IC 623877 were found to be early general combiners. For kernel rows IC 636977, IC 623873, for 100 kernel weight IC 623877, for shelling percentage IC 627707 and for SPAD chlorophyll content IC 623878 were good general combiners. Among the testers, BML-6 was good general combiner for ear diameter, number of kernel rows and number of kernels per row and BML-7 was good general combiner for thousand seed weight and SPAD chlorophyll content and for grain yield and plant height both were found to be good general combiners. For flowering, maturity traits and for shelling percentage KML-109 was a good general combiner. Of all the forty five hybrids tested, nine crosses had positive and significant effects for grain yield and among these, four crosses involving BML-6 as tester with four lines i.e. IC 623873, IC 623875, IC 636965 and IC 627708, three crosses involving BM-7 as tester with three lines i.e. IC 611615, IC 623878 and IC 623879 and two crosses viz. IC 611611 × KML-109 and IC 623878 × KML-109 were good specific combiners for grain yield (Table 3). Among these, three crosses namely IC 623873 × BML-6, IC 623878 × BML-7 and IC 627708 × BML-6 had shown positive and significant effects for ear and grain traits i.e. ear length, number of kernel rows, number of kernels per row and 100 kernel weight and the first two had positive and significant effects for ear diameter also. Remaining crosses except IC 611615 × BML-7 had positive and significant effects for either one or two of the ear traits. For SPAD chlorophyll content IC 623877 × BML-7 had positive and significant effect. All the nine crosses had either one or both parents as good general combiners for grain yield. It clearly indicated that possibility of good specific combinations by involving good general combiners for yield and yield attributing characters. Further based on per se performance only four crosses IC 627708 × BML-6 IC 623875 × BML-6, IC623873 × BML-6 and IC 611611 × KML-109 had significant effects for grain yield with grain yields of 13178 kg/ha, 12634 kg/ha, 11933 kg/ha and 11654 kg/ha, respectively and the IC 611611 × KML-109 was an early hybrid. The high yields obtained from some of the crosses indicate the potential to raise yield substantially in maize landraces when crossed with suitable materials. Similar findings have been reported in other studies as reported by Dhillon et al., (2002); Prasanna, (2012). It revealed that one of the parent must be a good general combiner in the exploitation of land races for getting high yielding hybrids but not necessarily a good specific combiner.