<![CDATA[In 2023, rice production for population consumption in Central Kalimantan decreased by 7.80 thousand tons (3.82%), due to a 13.14 thousand-ton decrease in dry milled grain (GKG). This is due to environmental stress and resistance to diseases and pests, which affect rice quality and productivity. Rice (O. sativa L. var. siam epang) is a rice that has advantages such as resistance to acidic soil pH, high rainfall, resistance to pests, and diseases. The success and occurrence of callus regeneration in vitro are generally influenced by PGR with appropriate concentrations. This study aimed to determine the most appropriate concentrations of PGRs 2,4-D and BAP to induce callus in Siam Epang rice. This study is an experimental factorial Completely Randomized Design (CRD) with two treatment factors, namely 2,4-D and BAP, at concentrations of 1 ppm, 2 ppm, and 3 ppm, respectively. Data analysis was conducted on qualitative and quantitative data, including research parameters such as callus formation time, callus weight, callus color, callus texture, and the percentage of explants forming callus. The results showed that the combination of 2,4-D and BAP PGR concentrations affected the growth of Siam Epang rice seed scutellum explants. The addition of 1 ppm 2,4-D and 0 ppm BAP PGR resulted in the fastest callus formation time, namely 3 days. Meanwhile, the addition of 3 ppm 2,4-D and 1 ppm BAP PGR resulted in the highest percentage of explants forming callus (100%) across all treatments. 1 ppm 2,4-D and 0 ppm BAP produced a fresh weight of 0.15 g, a dry weight of 0.03 g, and a callus weight of 0.09 g, the highest among all treatments. The callus formed was ivory white, yellowish white (cream), light yellow, and blackish brown with a compact texture. Thus, the combination of PGR concentrations that produced the highest percentage of callus formation in Siam Epang rice callus was 3 ppm 2,4-D and 1 ppm BAP, with 100% of explants forming callus. Further research is needed to evaluate the effects of various combinations of 2,4-D and BAP concentrations on Siam Epang rice callogenesis.]]>
