Agronomic Performance of Aromatic Rice (BC4F1) Derived from Inpari 33 × Merah Wangi Crosses

Abstract

Background: Aromatic rice quality is primarily determined by loss-of-function mutations in the BADH2 gene, which lead to the accumulation of 2-acetyl-1-pyrroline (2AP). This study aimed to introgress the BADH2 aromatic allele from Merah Wangi into the high-yielding variety Inpari 33 and to evaluate the agronomic performance of the resulting BC4F1 population. Methods: A breeding program consisting of four backcross cycles was conducted using Inpari 33 as the recurrent parent and Merah Wangi as the donor parent. Marker Marker-assisted breeding using Bradbury markers was applied to identify plants carrying the BADH2 mutation. Agronomic traits, including heading date, plant height, panicle length, tillering capacity, yield components and grain quality were assessed to characterize phenotypic performance. Result: Twenty heterozygous aromatic plants were identified, confirming successful introgression of the BADH2 mutant allele. The BC4F1 population showed uniform heading date, intermediate plant height and increased panicle length relative to Inpari 33. The productive tillers, filled grains per panicle and grain yield per plant demonstrated improved performance, even though variability persisted in grain filling and 1000-grain weight. These findings indicate that the integration of the BADH2 allele and the overall agronomic response validate the effectiveness of Marker Assisted Breeding combined with repeated backcrossing for developing improved aromatic rice lines, while further selection is still required to stabilize key traits.