Agronomic characterization and background selection of BC3F1 inpari-30 × Cabacu rice lines using SSR markers for drought and submergence tolerance.

Rice with extensive adaptation is needed in maintaining rice production. Breeding through backcrossing between the recurrent parent (RP) cultivar 'Inpari-30' and the donor parent (DP) 'Cabacu' was carried out to obtain new varieties tolerant to drought and submergence stresses. Cabacu was confirmed to carry QTL qRPF 2.1, qGPP 2.1, and qSPP 4.1, and Inpari-30 had Sub1, which were related to drought and submergence. Backcross breeding is time-consuming but can be shortened by using marker-assisted backcrossing (MABC) selection method. In the present study, MABC was carried out in background selection aimed at obtaining individuals with a high percentage of genomic recovery from the RP supported by agronomic trait observation. The population used was BC3F1 lines that were selected for foreground selection. Agronomic characterization was carried out after the generative phase. The 61 selected polymorphic microsatellites were used to genotype 10 lines and were scattered on all 12 linkage groups. Agronomic characterization showed that line D21.18 had similar agronomic characters as those of the parent cultivar Inpari-30 and root characters as those of the DP genotype 'Cabacu'. The percentage of the obtained recurrent parent genome (RPG) recovery ranged from 84.10% to 95.30%. The highest percentage of RPG recovery was observed in line D21.18 (95.30%). Therefore, rice line D21.18 can be used as the next selection material for further investigation in rice breeding programs.