Combining Ability and Group Classifying of Purple Tian Corn (Zea mays L.) Inbred Lines
Tian corn is a locally adapted crop that is grown in every region of Thailand. Developing new varieties of purple Tian corn could help rural consumers gain easy access to healthy food. In plant breeding, determining the genetic components and combining ability of different lines can help inform the effective use of available germplasm. The objective of this research was to study the genetic make up of purple Tian corn inbred lines and to divide them into heterosis groups using the Line x Tester method. A total of45 crosses were made, planned in factorial design, between 15 selection lines of inbred purple Tian corn (Line; L) and 3 tester lines of inbred yellow Tian corn (Tester; T). The hybrid seeds were planted out in randomized complete block design along with seeds of the 3 tester lines and 2 check varieties for comparison. Variance was analyzed for each factor separately using line x tester analysis. The results showed that additive genetic effects played an important role in determining the traits of number of ears, ear size and silking time of the purple Tian corn inbred lines, so these traits can be selected for in the first generation. Dominance genetic effects played a more important role in determining the traits of ear weight, both with husk and unhusked. The specific combining ability values for ear weight could be used to separate the selection lines into 2 heterosis groups with different gene frequencies at different loci: Group 1 (L1, L5, L9, L13 and L14) and Group2 (L3 and L8). For future purple Tian corn breeding efforts, these inbred lines can be further selected for a higher frequency of genes for the desired traits before performing additional crosses to test the specific combining ability of different parental pairs.
Index Terms - Genetic background, genetic effects, hybrid corn, maize breeding, waxy corn