Quality of Local Rice Genotypes and Their Improvement With Urea and Fermented Rice Husk Ash

The quality and nutritional value of rice ( Oryza sativa L.) are important for its economic value and for addressing malnutrition in developing countries. This study aims to identify local rice genotypes exhibiting high quality and high protein across various agroecosystems, and to increase rice protein content (PC) through the application of urea and fermented rice husk ash (FRHA). The first experiments were conducted in irrigated, tidal, and upland fields in Riau Province, Indonesia, during the years 2020–2021. The research was managed according to a randomized complete block design (RCBD) with three replications. In the second experiment, the organosol upland of Siak Regency, Indonesia, within the periods of 2022–2023 was used to test genotypes exhibiting low rice quality and protein levels using urea and FRHA as a source of silica (Si). The research was designed according to RCBD, replicated twice. Based on the results across the three agroecosystems, genotypes have been found that produce head rice recovery (HRR) >90% and PC > 9%, that is, Putri Malu in tidal, Cupak Putio Rendah and Kuning in irrigated, and Napal Merah and Sisungke in upland. The use of urea and FRHA together can enhance the HRR and PC of upland rice. The PC of Kalpatali Rambah Hilir (KRH) increased significantly from 7.57% (300 kg ha −1 urea and 0 kg ha −1 FRHA) to 10.37% by increasing FRHA (300 kg ha −1 urea and 1000 kg ha −1 FRHA).