Improvement of large-seeded waxy corn (Zea mays L. var. ‘Ceratina Kulesh’) populations for food and industrial purposes

Abstract

Improving large-seeded waxy corn for food and industrial purposes is one way to increase the value and utilization of new corn cultivars in Thailand. This study aimed to evaluate the agronomic traits, yield and yield components, and response to downy mildew (DM) disease caused by Peronosclerospora sorghi of the developed breeding lines of large-seeded waxy corn. A total of 33 waxy corn breeding lines with different seed sizes, row numbers, and kernel colors were selected from 2015 to 2018. The yield experiment was conducted at the Khon Kaen University, Khon Kaen, Thailand in the 2019/20 dry season and the 2020 rainy season. The breeding lines were also screened for DM resistance through artificial inoculation with spore suspension at farmers’ fields in two locations, namely, Sok Muang and Nong Bua, in the 2020 rainy season. Genotype had a significant effect on yields, yield components, and agronomic traits. However, the interactions between genotype and season were not significant for 1000-kernel dry weight and the number of rows per ear. ‘DRP-4’, RLW-4’, ‘RLW-6’, ‘RLW-7’, and ‘RLW-10’ showed the highest 1000-kernel dry weight and the optimal number of rows. Corn grown at Sok Muang Village had higher disease severity than that grown at Nong Bua Village due to the high rainfall, low temperature, and high humidity at the area. The resistant check cultivar ‘Nei9008’ exhibited moderate resistance to DM at both locations. Although the inbred lines were susceptible to DM disease, they appeared to be a good source of large seeds. Therefore, the backcross breeding method is still needed to obtain DM-resistant germplasm for the further development of waxy corn cultivars.