Regulations in 2-acetyl-1-pyrroline contents in fragrant rice are associated with water-nitrogen dynamics and plant nutrient contents.

Water (W) and nitrogen (N) have pronounced effects on 2-acetyl-1-pyrroline (2AP) contents and nutrient acquisition in fragrant rice. Field experiments were conducted during the early (March–July) and the late (July–November) seasons of 2013. Two water regimes i.e., W0 (well-watered, soil water potential was 0 kPa) and W1 (soil water potential was −25± 5 kPa) and two nitrogen levels i.e., N0 (0 kg N/ha) and N1 (60 kg N/ha (applied in addition to basal dose) were applied to two fragrant rice cultivars i.e., 'Nongxiang 18' and 'Basmati 385' at booting stage. All treatments were applied with 90–90-195 kg N–P–K ha−1 as basal fertilizer and at five days after transplanting, more N was added at 30 kg/ha. Results showed that the interactive effects of W and N influenced 2AP content in grains of both aromatic rice cultivars in both seasons. Compared to W1N0, the 2AP contents of 'Nongxiang 18' and 'Basmati 385'were increased by 37.74% and 55.78% as well as 68.35% and 47.10% at W1N1 for early and late season, respectively. Moreover, W1N1 increased total nitrogen contents in leaves and total potassium contents in leaves and stem sheath of both rice cultivars, whereas, grain 2AP contents were significantly related to the total N and N/P ratio in leaves. • Soil water potential −25± 5 kPa improved the grain 2AP contents substantially. • Reduced water and additional N application increased N and K contents in leaves. • The grain 2AP contents are significantly associated with N and N/P ratio in leaves. • The grain 2AP contents in late season were substantial higher than early season rice. [ABSTRACT FROM AUTHOR]