AGRIVITA Journal of Agricultural Science. 2020. 42(1): 174–190 AGRIVITA Journal of Agricultural Science www.agrivita.ub.ac.id 174 INTRODUCTION Globally, maize (Zea mays L.; 2n = 20) is the third important food crop after rice and wheat in terms of area and production. It has multifaceted uses as food, feed and basic raw materials for number of industries such as oil, food, protein, alcoholic beverages, starch, sweeteners, and biofuels. Demand of maize is exponentially increasing worldwide, especially as feed in poultry and pig industries. The major challenges like changes in environments, decrease in land fertility, limited resources, high demand, etc. put thrust over maize production. Heterosis breeding is one of the most potential approaches to combat the threats of maize production. Heterosis expresses the superiority of F 1 s over their standard and better parents, but fails to identify the possible causes of the superiority of hybrid (Amiruzzaman, Islam, Hasan, Kadir, & Rohman, 2013). Farmers merely preferred hybrids to other varieties due to their yield potential. The success of hybrid development is fundamentally depended on the genetic variability in the base population and the development of superior inbreds. In a conventional breeding approach, potential inbred lines are important to be identifed for hybridization and cross to expand the variability of genetic for the superior genotypes selection (Hallauer & Miranda Filho, 1988). Combining ability plays an important role in crop improvement such as maize, as it helps to identify potential parents that can be used for producing hybrids and synthetics (Vasal, 2000). To assist research on hybrid development, the information about heterotic patterns and combining ability among gene pools and populations are needed (Beck, Vasal, & Crossa, 1990). A sound breeding ARTICLE INFO Keywords: Combining ability Heterosis Morphological traits Pearson’s correlation Quality traits Article History: Received: December 8, 2018 Accepted: January 23, 2020 * ) Corresponding author: E-mail: tnagr01@gmail.com ABSTRACT The research aimed to study heterosis, combining ability and performance along with their inter-relationship across three environments. Variance due to general (GCA) and specifc combining abilities (SCA) and their interaction with environment was found to be signifcant for most of studied traits. For all the studied traits but ASI (Anthesis-silking interval), HI (Harvest index) and starch content, additive gene action was highly important than non-additive gene action for their expression as refected by Baker's ratio which was near to unity. CML439, R13-1-1 and Tarun83-1-3-2 were the best general combiner for starch, protein and oil, respectively. R13-1-17, CML439 and Tarun83-1-3-2 were good general combiner for maturity characters and harvest index while TSK 196 and TSK 197 were good general combiner for cob length, cob girth, number of grains/row and grain yield. DMR9047×R13-1-17 and POP31Q×Tarun83-1-3-2 showed desirable heterosis and SCA efect for maturity characters. Regarding to SCA and heterosis, the prominent hybrids for grain yield were TSK197×R13-1-10, TSK194×POP31Q, DMR9047×POP31Q and R13-1-1×DMR9047. SCA established stronger relationship with per se performance of grain yield and quality traits than mid-parent (MPH) and best-parent heterosis (BPH), refecting that an improvement in selection of SCA will results in an indirect improvement of MPH and BPH of hybrids. ISSN: 0126-0537 Accredited First Grade by Ministry of Research, Technology and Higher Education of The Republic of Indonesia, Decree No: 30/E/KPT/2018 Cite this as: Bhusal, T. N., & Lal, G. M. (2020). Heterosis, combining ability and their inter-relationship for morphological and quality traits in yellow maize (Zea mays L.) single-crosses across environments. AGRIVITA Journal of Agricultural Science, 42(1), 174–190. http://doi.org/10.17503/agrivita.v42i1.2089 Heterosis, Combining Ability and Their Inter-Relationship for Morphological and Quality Traits in Yellow Maize (Zea mays L.) Single-Crosses Across Environments T. N. Bhusal *) and G. M. Lal Department of Genetics and Plant Breeding, Sam Higginbottom University of Agriculture Technology and Sciences, Allahabad-211007, Uttar Pradesh, India