Nitrogen and α-Ketoglutaric Acid Application Modulate Grain Yield, Aroma, Nutrient Uptake and Physiological Attributes in Fragrant Rice

The present study was conducted to assess the effects of nitrogen (N) and oc-ketoglutaric acid application morpho-physiological attributes, aroma regulations and nutrient uptake in fragrant rice. Two fragrant rice cultivars i.e., Yungengyoul4 and Yuxiangyouzhan were grown under two N levels i.e., LN: 0 g pot(-1) and HN: 1.75 g pot(-1) and two alpha-ketoglutaric acid levels i.e., - A: 0 mg l(-1) and + A: 100 mg l(-1), applied at 25 ml pot(-1). Results showed that the HN - A and HN + A treatments significantly improved the panicle number per pot in Yuxiangyouzhan and Yungengyoul4 as compared with LN - A treatment. The HN + A treatment led to substantial improvements in grain yield owing to increased panicle number per pot, grain number per pot, and grain weight. Significant effects of HN + A treatment on agronomic traits such as plant height, leaf dry weight, steam sheath dry weight, panicle dry weight and total dry weight were also noted. Compared with LN - A treatment, the HN - A and HN + A treatments significantly increased the 2-acetyl-1-pyrroline (2AP) contents in grains of Yuxiangyouzhan (7.0% and 15.7%) and Yungengyoul4 (47.3% and 43.4%). Under HN + A treatment, the 2AP content in grains as well as the 2AP content in leaves at the heading stage and PSCS activity in leaves increased at the maturity stage as compared with LN - A treatment. Furthermore, the grain 2AP content was significantly and positively related to PSCS activity, as well as Mn and Ca contents in plants. Overall, the application of N and alpha-ketoglutaric acid modulated the growth, yield, and aroma in fragrant rice, whereas N tends to have more prominent effects on the investigated parameters than alpha-ketoglutaric acid.