Heterosis analysis of F₁ progenies derived from IS21 × MR220CL2 and IS21 × UKMRC16 crossing combinations

Abstract

A new high-yielding mutant rice cultivar, IS21, has been released by the Malaysian Nuclear Agency (MNA) in 2021. This cultivar matures in 105-108 days after transplanting. Since there is a need to reduce days to maturity (DTM) in most Malaysian rice mega-varieties to minimise the impacts of abiotic and biotic stresses, crossing IS21 with early maturing rice genotypes could be an efficient strategy to address these issues. Preliminary screening has successfully identified two early maturing and shorter plant statue rice genotypes, MR220CL2 and UKMRC16. Therefore, these rice genotypes were crossed to IS21 to generate two F1 populations. These F1 populations (IS21 × MR220CL2 and IS21 × UKMRC16) were planted in the MNA glasshouse with parental lines from December 2021 to March 2022. The agro-morphological data for F1 populations and parental lines were recorded and analysed using the RStudio software package. The putative F1 progenies were confirmed using two polymorphic simple sequence repeat (SSR) SSR markers, RM628 and RM140. About 75% of the putative F1 are F1 hybrids. IS21 × MR220CL2 F1 progenies showed better morpho-agronomical performances compared to IS21 × UKMRC16 F1 progenies. This crossing combination also had positive mid-parents and better parent heterosis values of all evaluated traits except for thousand-grain weight, days to flowering and DTM. This study suggested the potential use of IS21 x MR220CL2 F1 progenies for rice breeding programmes with high-yielding and early maturity traits.