Genetic variability and traits association analyses on F2 generations for determination of selection criteria in Indonesian inland swamp rice breeding

Abstract The progress of rice breeding program for better adaptation and extension on inland swamp ecosystem largely depends on the presence of genetic variability and relevant selection criteria. This study was undertaken to estimate the genetic variability parameters in segregating populations of rice and to determine the relationship of grain yield and yield contributing traits of rice to determine selection criteria for yield improvement under inland swamp condition. The F2 population was generated from 11 crosses involving Bengkulu landraces of swamp rice. Then, the F2 population was evaluated on the inland swamp for their yield and yield-related traits. The genetic parameter was estimated using variance component analysis. Simple correlation analysis was performed for all observed traits and the resulting matrix of correlation coefficients was subjected to factor analysis and path analysis. Analysis of variance indicated that significant variation present among and within F2 families for most of the traits studied. Grain yield plant-1 exhibited the highest GCV (40.3 %) and PCV (60.11%). Moderate to high or moderate h2B with high GAM was obtained on plant height, tiller number, number of productive tiller, spikelet number panicle-1, 100-grain weight, and grain yield plant-1. Positive and significant correlation was found between grain yield plant-1 and plant height, tiller number, spikelet number panicle-1, panicle length, and 100-grain weight. Factor analysis discerned the 9 observed traits into two-factor axes with overall explaining 79.28% of the total variation among traits. The first factor (59.12%) was strongly characterized by yield and yield components (plant height, tiller number, number of productive tillers, spikelet number panicle-1, panicle length, and 100-grain weight), whereas the second factor (20.16%) was mainly associated with heading date. Path analysis revealed that among the yield components, tiller number and 100-grain weight (the grain size) had strong direct effects on grain yield and they can be taken into account as the selection criteria for rice grain yield improvement under inland swamp ecosystem. Keywords: rice, inland swamp, genetic parameters, factor analysis, path analysis, selection criteria. Abbreviations: GCV_Genotypic Coefficient of Variation; PCV_Phenotypic Coefficient of Variation, GAM_Genetic Advance as Percent of Population Mean; h2B_Broad Sense Heritability