Development of S1 Inbred Lines and Estimating the Inbreeding Depression in Two Populations of Maize (Zea mays L.)

Three way lines have been successfully incorporated in the breeding program of corn. However, the developing countries are still breeding the corn varieties using conventional scheme of inbreeding. Although inbred lines developed through conventional method having more success rate as they are getting acclimatized during the process of inbreeding. To know the effect of inbreeding depression a study was conducted in the Agricultural Experimentation Block of the University of Swabi, during the two cropping seasons of 2013-2014. The S₁ inbred lines were developed from two of the maize populations viz. popcorn and sweet corn. The parental population had shown a high degree of significance (P≥0.01) for plant height. Most of the traits had shown absolutely stable performance with least or no differences. Of the developed 20 S₁ inbred lines, mean data revealed that maximum reduction in plant height (169.55 cm) was observed in inbred lines developed from popcorn as compared to that of sweet corn (159.65 cm). The study suggests that although theoretically proven that in each subsequent generation of selfing the 50% reduction will be observed. However, this study proved that most of the agronomic traits remain unchanged in 1^st generation of inbreeding the maize indigenous cultivars. It also suggested that preference should be given to the line with maximum homozygosity at later stages and with less inbreeding depression.