BIODIVERSITAS ISSN: 1412-033X Volume 23, Number 9, September 2022 E-ISSN: 2085-4722 Pages: 4649-4656 DOI: 10.13057/biodiv/d230931 The shifting genetic diversity pattern of Indonesian rice improved varieties from 1943-2019 based on historical pedigree data ANAS 1, , FARIDA DAMAYANTI 1 , MOHAMAD KADAPI 2 , NONO CARSONO 1 , SANTIKA SARI 1 1 Laboratory of Plant Breeding, Faculty of Agriculture, Universitas Padjadjaran. Jl. Ir. Soekarno Km 21, Jatinangor, Sumedang 45363, West Java, Indonesia. Tel./fax.: +62-22-84288828,  email: anas@unpad.ac.id 2 Laboratory of Seed Science, Faculty of Agriculture, Universitas Padjadjaran. Jl. Ir. Soekarno Km 21, Jatinangor, Sumedang 45363, West Java, Indonesia Manuscript received: 25 May 2022. Revision accepted: 8 September 2022. Abstract. Anas, Damayanti F, Kadapi M, Carsono N, Sari S. 2022. The shifting genetic diversity pattern of Indonesian rice improved varieties from 1943-2019 based on historical pedigree data. Biodiversitas 23: 4649-4656. For rice plants in Indonesia, stagnation in increasing crop yields due to a reduction in genetic diversity is a significant issue. The issue of using the same parents in breeding programs and consumer preferences for a single main variety are among the causes of the narrowing of rice plants' genetic diversity. The purpose of this study is to figure out which ancestors are significant and how the genetic diversity of improved Indonesian rice cultivars has changed over time. Changes in the genetic background of the Indonesian rice gene pool were decided using pedigree analysis by calculating the coefficient of parentage (COP) among varieties. There are 280 ancestors in the rice gene pool. The pedigree map exemplifies the complexities of rice breeding in Indonesia. The four classical ancestors of DGWG, Taichung Native1, China, and Latisail had a noteworthy influence on all irrigated rice plant types (11.22%) and upland rice plant types (8.30%) in the gene pool. The dominance of the phenomenal variety IR64 has been continued by Inpari 32, which is a direct derivative of Ciherang. In the meantime, Inpago9, Luhur 2, and UPLRI ancestors set the foundation for the upland rice plant type. Inpara7 and Inpara9, along with their IRRI- introduced parents (IRRIpara4 and IRRIpara5), had a significant impact on Indonesian tidal rice plants. The A1, Hipa7, and Hipa3 varieties are heavily influenced by the hybrid rice plants of Indonesia. Keywords: Genetic background, improved variety, pedigree analysis, rice INTRODUCTION Recently, the world has been confronted with serious problems in the restrictiveness of the food supply. The increase in food demand and the decrease in rice production have contributed to the food crisis in the world. Global climate change impacts prolonging the dry season in Indonesia, temperature increases, and decreases in plant productivity (Aragón et al. 2021; Malhi et al. 2021). The fourth-largest Indonesian population is expected to reach 306 million by 2035 (BPPN et al. 2013), necessitating an increase in rice production of more than 2 million tons of dry milled grain from base rice production in 2019 (BPS 2017, 2020). The decline of genetic diversity has become a global issue, and high genetic diversity is most important for the sustainability of agriculture, ecosystems, and crop improvement (Hoban et al. 2021; Swarup et al. 2021). The national rice breeding program is closely related to the history of IRRI rice-released cultivars. A significant increase in rice productivity in Indonesia was achieved from 1981 to 1990 and has been associated with the introduction of the high-yielding Cisadane cultivar. Almost every modification of the pedigree selection method was applied by breeders to improve plant yield. However, the average rice productivity in the next decade decreased and was constant at a rate of 1.19%. If there isn't enough genetic diversity in the parents that are used to make populations through hybridization, there may be less genetic variation for quantitative traits. The Indonesian government has released more than ±328 superior rice varieties over the last 76 years, and during the period 2008-2019 has released ±110 superior rice varieties (10 varieties per year). However, the average contribution of this new variety to the increase in rice productivity is only two kg ha-1 annually. The increase in rice productivity in Indonesia for 76 years only ranges from 4.89 to 5.11 tons ha-1 (BPS 2020), and is slightly below Vietnamese and Japanese rice productivity, which on average is 5.53 tons ha-1 and 6.68 tons ha-1, respectively (FAOSTAT 2020). Genetic background and the presence of genes are essential for success in rice breeding programs. Improvement of the character controlled by a polygene is constantly crucial in plant breeding programs. A molecular approach for improving the quantitative character of rice through QTL analysis has been investigated by several researchers (Bakti and Tanaka 2019; Baltazar et al. 2019; Jewel et al. 2019; Liu et al. 2020; Sandhu et al. 2021; Zhao et al. 2022). However, molecular techniques are expensive, labor-intensive, and difficult to apply in countries with limited resources. Pedigree analysis has been widely used in plant breeding programs (Egan et al. 2019). The high selection pressure of rice breeding has been focused on high yield and tolerance to pests and diseases. It usually breeds without considering the proper selection of the parent's genetic background and might result in a