The fulfillment of increasing demand for nutritious diet is a continuous global challenge especially for developing regions such as sub-Saharan Africa (SSA) where majority of inhabitants still depends on agriculture. Notably, the prevalence of under-nourishment appears to have risen in SSA from 20.8 to 22.7 percent between 2015 and 2016 and the number of people undernourished rose from 200 to 224 million, accounting for 25 per cent of the people undernourished in the world (
FAO, 2017). Accessibility of animal protein is a constraint for majority of Africa’s populace, as it is quite expensive, hence, they often consume starch based diet especially root and tuber crops (
Schonfeldt and Hall, 2012). Soybean can serve as a dietary substitute for higher-fat animal products, because soybean seeds contain about 37-42% protein content with all essential amino acids and 17-24% oil content comprising 85% poly un-saturated fatty acid with two essential fatty acids free from cholesterol (
Balasubramaniyan and Palaniappan, 2003). Nigeria occupies maximum soybean acreage in SSA but ranks second in soybean production after South Africa (
FAOSTAT, 2017). In Nigeria, soybean is consumed in the form of various food products such as
dawadawa (a traditional soup condiment), soy
ogi, biscuits, soy flour, soy yoghurt and soymilk (
Poopola and Akueshi, 1986). Therefore, increase in soybean production may help to address the challenges of food and nutritional security in Nigeria.
However, tropical regions, like Nigeria are characterized by hot and humid weather conditions which enhance the incidence of pest and diseases such as soybean rust (SBR) caused by
Phakopsora pachyrhizi. The yield loss due to SBR may vary but it has the potential to cause more than 80% yield loss under favourable conditions
(Chander et al., 2019). For any successful breeding programme to improve quantitative characters such as grain yield, it is essential to know precisely the genetic factors contributing to yield and its related characters
(Nath et al., 2018). According to
Dar et al., (2014), per se performance of parents is not always a true indicator of its potential, rather a combining ability study is needed. Among the various ways of determining the combining ability potential of parents and crosses, line × tester analysis is most commonly used method which was initially developed for selecting suitable parents with good general combining ability (GCA) and crosses with high specific combining ability (SCA) for exploitation in pedigree breeding (
Kempthorne, 1957). However, there are few reports to utilize line × tester analysis for combining ability analysis in self-pollinating crops such as soybean
(Bastawisy et al., 1997; Sood et al., 2000; Mebrahtu and Devine, 2008). The present study was, therefore, undertaken to evaluate the combining abilities of five IITA released varieties using three plant introduction (PI) accessions as testers which are source of resistance against SBR.