Genotypic Variation in Thai Fragrant Rice in Response to Manganese Application and Its Effects on 2-Acetyl-1-Pyrroline Content, Productivity and Gene Expression

The fragrance in rice plays a significant role in consumer decisions and is influenced by many environmental factors, e.g., water and fertilizer application during cultivation and post-harvest management. Manganese (Mn) is an essential micronutrient for plant growth and development, and its effects on the fragrance and yield of fragrant rice varieties have not been well-studied. The aim of this research was to determine the effects of Mn application rates on the 2-acetyl-1-pyrroline (2AP) content, yield and gene expression of Thai fragrant varieties. Three rice varieties, i.e., BNM4, KDML105 and KH-CMU, were grown in pots with varying concentrations of MnSO4-150, 200 and 250 mg kg(-1) soil-and compared with a control with no Mn application (Mn0). At maturity, the grain yield was evaluated, and the 2AP was analyzed with GC-MS as the grain aroma content. Taken together, the results suggest that Mn application during cultivation tends to increase the 2AP content of fragrant rice and its productivity and tends to affect gene expression. However, it is important to conduct further studies to evaluate the responses for more fragrant rice varieties and additional gene expression, including the determination of key intermediate compounds along the 2AP biosynthesis pathway to confirm the effect of Mn application on fragrant rice. This information could be useful in assisting plant breeders and physiologists in their efforts to improve the crop productivity and grain quality of fragrant rice varieties.