This study builds upon a previous one that aimed to determine the effect of spent mushroom substrate extract (SMSE) as a biofertilizer on the growth of Sakha 103 rice verity. A useful method to extract Plourotus mushrooms is to use water. These result in highly nutritious organic fertilizers that can improve rice growth, quality, and yield. The study involved soaking rice grains in SMSE, followed by application through three methods: spraying on the rice shoot system, soil drenching, and a combination of both spray and soil drenching. The most effective method to add fertilizer is to use a combination of spraying and amendment with irrigation water. Spent extract (SMSE) contains a significant amount of phenolic compounds, reducing sugars, and other macro- and micro-elements that can be beneficial for the growth of rice. Eight different treatments were selected based on their productivity and evaluated for their rice quality assessment. Treatments (P3Ss) and (P3Sw) scored significantly higher in protein, ash, and fiber but showed a significant decrease in amylose content. The cooking time for all grains ranged between 17 and 20 minutes. There were no significant differences in the thousand grain weight for most treatments, except for P3Sw and P3Ss, which had a high significant value of 28.5 g for both. All treatments were grouped based on their length and L/W ratio and were classified as either short or bold grains. In terms of color, there were noticeable distinctions between all treatments and the control group. Also, treatments (P3Ss) and (P3Sw) were found to have higher levels of whiteness and lightness compared to other treatments. Additionally, T3 and T7 treatments received the highest ratings for overall acceptability in terms of sensory attributes.