Effects of Nitrogen Fertilizer on Grain Yield and Fragrant Contents in two Thai Rice Varieties

Nitrogen (N) is commonly applied in rice crop production for improving grain quality and productivity. This experiment aimed to evaluate how applying N fertilizer affects the concentration of 2-Acetyl-1-Pyrroline (2AP), the major fragrant compound in rice grains, between two selected rice varieties with high yield potential and fragrant scent, Pathum Thani 1 (PTT1) and RD22. Rice plants were grown in pot conditions and N fertilizer was applied in three rates at 2.44, 3.82 and 5.66 g N/pot designated as N1, N2 and N3, respectively. Rice samples were harvested at maturity and evaluated for grain yield, grain N and 2AP concentration. The results revealed that grain yield and concentration of N and 2AP were affected by N rates differently between the varieties; RD22 had higher grain yield and the concentrations of N and 2AP than PTT1 with all N rates. Grain N concentration in both varieties increased when increasing N rates. There was highly positive correlation between grain N and grain 2AP concentration among the N rates and varieties. We conclude that applying N in rice cultivation not only improves productivity but also enhances the quality of rice grains by improving the concentrations of N and 2AP, the magnitude of the effect depending on the rice variety.