Effects of Sowing Date and Nitrogen (N) Application Rate on Grain Yield, Nitrogen Use Efficiency and 2-Acetyl-1-Pyrroline Formation in Fragrant Rice

Purpose: This study aimed to assess the effects of sowing date and nitrogen application rate on grain yield, use efficiency (NUE), 2-acetyl-△1-pyrroline (2-AP) contents biochemical parameters related 2-AP formation in fragrant rice. Methods: A factorial split-plot arrangement treatments was set up a split-zone experiment with two factors three levels carried out for 3 years. The main plots included dates: April 1st May 1st. Subplots contained different i.e., 0 kg N ha−1 (N0), 120 (N1) 180 (N2). Results: results indicated that compared 1st, delay (May 1st) decreased number grains per panicle, 1000-grain weight, NUE 2-AP, △1-pyrroline, proline pyrroline-5-carboxylic acid (P5C), as well dehydrogenase (ProDH) activity. Furthermore, N0, higher-N (N1 N2) applications increased panicle number, yield P5C, activities ProDH ornithine aminotransferase (OAT). seed-setting rate, weight were under N2 N1, but content higher high-N (180 ha−1) N1 (120 ha−1). Conclusions: Sowing improved promoted biosynthesis, while reduced content. Therefore, is best, which can not only ensure also improve quality