Studying Heritability and Heterosis of Traits of Inbred Lines and Single Crosses Hybrids of Sweet Corn (Zea mays L.)

Sweet corn (Zea mays L.) is one of the most popular vegetable in many countries. It is characterized by translucent, horny appearance of kernel when matures and wrinkled when it dries. The efficiency of maize breeding programs would be significantly enhanced if superior crosses could be predicted before field evaluation based on screening of parental inbred lines. Even though remarkable advances in maize breeding have been achieved, field trials involve significant resources and are time consuming. However, field tests still have an irreplaceable role in modern hybrid breeding programs. Determining performances of maize inbred lines as potential hybrid parents in field experiments based on combining ability of inbred lines and heritability of traits that are related to grain yield is very important in breeding programs.
This experiment was conducted in Khorasan Razavi Agricultural and Natural Resources Research Center, Mashhad, Iran in 2012-2013. The experimental materials were 37 sweet corn genotypes consisting of 18 inbred lines and 19 single cross hybrids that were evaluated in complete block design (CRD) with three replications. In each plot, seeds were planted in two 5m length rows with 75cm between two rows. The final plant density was 7.6 plants per square meter. The measured traits were some of morphological and phenological characteristics, yield and yield components that were recorded for 10 competitive plants or ears in each experimental plot. Analysis of variance was performed by SAS ver 9.1. Means with significant differences were compared using Duncan’s multiple range tests.
The results showed significant differences between different sweet corn genotypes for all studied traits (p≤0.01). The mean comparison showed that hybrid Temptation* chase with 26.273 ton/ha has the highest conservable grain yield. Also, the highest heritability belonged to tassel length with 96.63 %. The most yield heterosis and heteroblitiosis were 280.72 and 337.1 percent in genotype Temptation 2* Chase, respectively. The cluster analysis divided genotypes to 4 clusters with inbred lines located in A and B clusters and single cross hybrids in C and D clusters.
We concluded that the selected elite single cross hybrids like Temptation*Chase can be used as good candidates for final comparison yield trials in future breeding programs.