Abstract

Haploid inducer maize facilitates rapid development of inbred lines. Haploid induction rate and accurate haploid identification are critical initial factors in doubled haploid line development. This study aimed to 1) evaluate haploid induction rates among different corn types (field corn, sweet corn, and waxy corn) and varieties using haploid inducer population, and 2) study haploid identification methods using the R1-nj anthocyanin marker and stomatal cell size. The three types of corn, comprising a total of six varieties, were crossed with haploid inducer population at the National Corn and Sorghum Research Center, Faculty of Agriculture, Kasetsart University. Each variety was planted in three plots. Haploid seeds were initially identified using the R1-nj anthocyanin marker. Putative haploid seeds of the six varieties were germinated at 50 seeds per tray with four replications. Haploid plants were then confirmed by microscopic observation and measurement of stomatal size. The results showed that the proportion of putative haploid seeds in field corn, sweet corn and waxy corn were relatively high, ranging from 7.98% to 19.92%, except S7328 (3.80%) and Hibrix 72 (5.96%). However, confirmation based on stomatal size revealed a low proportion of true haploid plants and a relatively high number of false positives. Haploid induction rates (HIR) varied among corn types and varieties, ranging from 0.40% to 0.72% in field corn, 0.62% to 1.39% in sweet corn, and 0.90% to 0.96% in waxy corn.