Genetic Variability, Inbreeding Depression, and Inheritance Pattern in F₃ Segregating Generations of Ten Exotic Hybrid Rice in Bangladesh

Hybrid rice technology offers a promising avenue for increasing productivity in Bangladesh, but the genetic potential of exotic hybrids and their segregating populations remains underexplored. This experiment aimed to evaluate the performance, level of inbreeding depression, relationships among different traits, and inheritance patterns of ten commercial hybrid rice varieties' F₃ generations through an augmented design with five blocks conducted at Bangladesh Agricultural University, Mymensingh, during July-December. Highly significant (P ≤ 0.01) genotypic variations were observed for plant height and five-panicle weight, while effects of the blocks were non-significant, indicating strong genetic variation. The differences in average performance were highly significant, with the tallest plant being Taj-2 (91.9 cm), the shortest Shurma (79.7 cm), the highest tiller number in ACI-2 (7.34), and the lowest in Hira-99-5 (4.52). The weight of five panicles was highest in Shonar Bangla (16.79 g) and lowest in Krishan-2 (13.03 g). Maximum inbreeding depression was seen in grain yield for Tia (48.36%) and in tillers for Hira-99-5 (45.07%), while inbreeding depression below 9.93% was recorded in ACI-2 and Shurma, which showed greater stability than other genotypes. Correlation analysis demonstrated a significant positive relationship between effective tillers and total tillers across all genotypes, whereas five-panicle weight showed both positive and negative correlations with other traits. Genetic inheritance studies indicated various types of genetic control, including monogenic, digenic, and polygenic influences on plant height, and monogenic control with partial and complementary gene action for five-panicle weight. Genetic variability was notably high in the F₃ generation. ACI-2 and Shurma emerged as the most promising genotypes for hybrid rice breeding in Bangladesh.