Inheritance and Gene Action of Salinity-Resistance-Related Traits in F1 Crosses of Resistant and Sensitive Maize

Maize is the third most cultivated cereal crop, following rice and wheat, and it is significantly affected by salinity stress. Maize performance under salinity stress can be improved by breeding. A thorough understanding of the traits associated with salinity stress, its inheritance, and gene action is needed for developing resistant varieties. This research aimed to study the inheritance and gene action of traits related to salinity stress in hybrid maize F1 crossbreed of ‘Elos’ and ‘Bonanza’ (BE & EB). ‘Elos’ was a salinity-resistant maize, ‘Bonanza’ was a salinity-sensitive maize, BE was F1 crossbreed with ‘Bonanza’ as the female and ‘Elos’ as the male and EB were the reciprocal. These maize varieties were planted in polybags containing a soil-sand mixture with a total weight of 10 kilograms (5 kg soil and 5 kg sand). Salinity levels were established by adding NaCl until the electrical conductivity (EC) reached 3 dS/m (low salinity) and 6 dS/m (moderate salinity); the control group was not treated with salt. The polybags were arranged in a randomized complete block design (RCBD) based on salinity levels and cultivar treatment, with each treatment replicated 20 times. The characters observed included plant height, stem diameter, leaf number, leaf length, leaf width, ear height, anthesis time, silking time, harvesting time, ear length, ear diameter, ear weight, seed number, the weight of 100 seeds, and total seed weight. The traits related to salinity were analyzed using a correlation test, and salinity resistance was assessed through the salinity tolerance index (STI). The indices were compared using ANOVA and Duncan's post hoc test, utilizing IBM SPSS version 25. This study also determined heterosis effects and gene action. The results indicated that the characteristics associated with salinity resistance in hybrids were inherited predominantly from the salinity-resistant parent, Elos (partially and over dominance), especially at low and medium salinity. At moderate salinity, the dominance of parent E remains dominant in most characters, while parent B has an effect on ear length and weight of one hundred seeds. This change in dominance reflects a shift in gene action due to increased salinity stress. Based on heterosis values, hybrids EB were better than BE in low and moderate salinity conditions, with positive values on production characteristics such as plant height, stem diameter, and seed weight. However, negative heterosis in anthesis, silking, and harvest time showed a decrease in salinity resistance compared to the parent. Gene action in EB and BE hybrids in salinity stress shows the dominance of additive gene action with complementary and duplicate epistasis effects. At moderate salinity stress, there was a change in gene action from complementary to duplicate in some characters, reflecting changes in resilience mechanisms due to increased stress. Overall, salinity resistance expression in EB and BE is controlled by many genes, with inheritance patterns shifting with stress levels. The variations in heterosis values and gene action highlighted the complex structure and interactions of genes involved in salinity resistance. Keywords: Salt accumulation, soil degradation, abiotic stress, gene action, heterosis, inheritance, toxicity.