Uthai Thani Native Small-ear Waxy Corn Improvement

Abstract

Native waxy corn varieties widely cultivated in Uthai Thani Province are Tein Yao and Tein Kareing. As open-pollination, these varieties have apparent genetic deterioration due to contamination from cross-pollinated, leading to variations in yield and quality. This study aimed to collect, select, and improve the native small-ear waxy corn of Uthai Thani to enhance varietal uniformity, prolific ear formation, and yield potential. From 2018 to 2023, the populations were improved through three cycles S₁NRS. Each selection cycle consisted of three steps: 1) self-pollination of population, 2) bulk half-sib pollination in population, and 3) randomly open pollination in population. Selection progress was evaluated in two growing seasons. Selection progress of Tein Yao improved population (YC3) and Tein Kareing improved population (KRC3) was compared to the base population, intermediate cycles, and commercial varieties. Results indicated that YC3 showed consistent positive responses to selection. Unhusked and husked yields increased by 169.1 and 116.2 kg/rai/cycle, respectively. The study also found that the total ear number and first ear number increased by 1,414 and 916 ears/rai, respectively, with high coefficients of determination. In contrast, KRC3 exhibited limited response to selection, with unhusked and husked yields of 61.4 and 39.6 kg/rai/cycle, although relatively high coefficients of determination were observed. Three cycles of S₁NRS was effective for improving Tein Yao and Tein Kareing populations with enhanced uniformity, prolific ear production, and high yield. The improved populations can be utilized as open-pollinated varieties and as valuable genetic resources for additional breeding programs focused on waxy corn.