Genetic components and heterotic performance of yellow maize hybrids for morphological and yield traits

Information regarding combining ability of the inbred lines is crucial for success in hybrid breeding of maize. The current study was designed to assess general combining ability (GCA) and specific combining ability (SCA) effects, and heterotic effects for morphological and yield related traits of yellow maize. Ten inbred lines and three testers were used to produce 30 F 1 crosses by using line × tester matting pattern. The resulting hybrids along with 02 checks were evaluated by using Randomized Complete Block Design (RCBD) with 03 replications at Cereal Crop Research Institute, Pirsabaq Nowshehra, Pakistan during Kharif 2022. Significant differences ( P < 0.05) were observed among the parents and crosses for all the studied traits suggesting that further selection is possible. GCA and SCA estimates of the parental lines and crosses were significant ( P < 0.05) for all the studied traits of yellow maize except ear diameter. The inbred lines YL-1, YL-2 and YL-8 RC were found to have desirable and negative GCA values towards earliness. The parental lines YL-1, YL-2 and YL-6 were observed to have desirable and significant positive GCA values for ear length, 100-grain weight and grain yield, indicating favorable additive genetic effects for these traits. Among the F 1 crosses, the cross combinations YL-2 × YD-4 (8629.5 kg ha -1 ), YL-6 × YD-4 (7617.5 kg ha -1 ), and YL-1 × YL-07 RC (7602.8 kg ha -1 ) were the high yielding hybrids having positive and significant SCA effects for grain yield. Among these crosses, YL-02 × YD-04 showed positive and significant economic heterosis (15.1%) and commercial heterosis (3.30%) for grain yield, highlighting its potential for further evaluation. Assessment of combining ability variances revealed a predominance of SCA variance over GCA variance for most traits, while Baker’s ratio values below unity indicated a greater contribution of non-additive genetic effects to the expression of the traits studied.