Identification of Promising Recombinant Inbred Lines (RILs) of Rice (Oryza sativa L.) for Enhanced Nutritional and Grain Quality Traits

Abstract

Aim: Micronutrient malnutrition is a serious global health concern, especially iron (Fe) and zinc (Zn) deficiencies. Rice (Oryza sativa L.), a staple grain consumed by over half of the world's population, has low concentrations of these vital micronutrients. The present study aims to identify promising recombinant inbred lines (RILs) that combine high nutritional quality with desirable grain quality traits. Place and Duration of Study: The study was conducted at ICAR–Indian Institute of Rice Research (IIRR), Rajendranagar, Hyderabad. Seed materials were generated during Rabi 2023-2024. Methodology: 20 contrasting recombinant inbred lines (RILs), comprising 10 with high and 10 with low grain iron and zinc content, were selected for comprehensive grain quality evaluation. The experiment was conducted in a randomized completed block design (RCBD) with three replications. Grain quality traits including milling efficiency, physical grain characteristics and cooking quality parameters were assessed following the standardized procedures. Results: Results revealed significant variation (p < 0.05) among the selected lines for all traits except hulling percentage. Iron and zinc content in brown rice was in a range of 8.60 to 14.40 ppm and 15.40 to 35.10 ppm, respectively. In terms of milling quality, hulling, milling and head rice recovery percentage was in a range of 73.30 to 79.20 %, 63.50 to 70.60 and 33.80 to 61.50 %, respectively. Most of the lines were classified into short bold and medium slender groups based on their kernel length and length to breadth ratio. Cooking quality traits such as volume expansion ratio, elongation ratio and water uptake value ranged from 4.00 to 5.60, 1.63 to 2.12 and 90 to 235 ml, respectively. Based on Amylose content RILs categorized into high (non-sticky) and intermediate (soft) groups. Similarly with gel consistency RILs were grouped into hard, medium and soft types indicating diverse cooking and eating quality profiles. Significant correlation was observed between iron and zinc content (r = 0.922**, p < 0.01), indicating that these micronutrients co-localize and can be improved simultaneously through genetic selection. Conclusion: The study identified IK1174, IK-1169 as promising RILs combining high grain iron and zinc content with acceptable grain and cooking quality traits. These lines hold potential for use in breeding programs targeting nutritional enhancement and consumer preferred grain quality in rice.