Additional Nitrogen Application Under Different Water Regimes at Tillering Stage Enhanced Rice Yield and 2-Acetyl-1-Pyrroline (2AP) Content in Fragrant Rice

Abstract

Water (W) and nitrogen (N) management at tillering stage could largely affect aroma biosynthesis in fragrant rice. In the present study, three rice cultivars, i.e., Basmati, Nongxiang 18, and Yungengyou 14, were applied with three N levels, i.e., 0, 30, and 60 kg N ha−1 regarded as N0, N1, and N2, respectively, and three water levels, i.e., well-watered treatment with water layer of 4–6 cm, 0 kPa (W1), soil water potential of ‒10 kPa (W2), and soil water potential of ‒20 kPa (W3), were applied at tillering stage during 2012 and 2013 under field conditions. Results depicted that application of N fertilizer and less irrigation water at tillering stage increased head milled rice yield and 2 acetyle-1-pyrroline (2AP) content in grain. The N2 and W3 treatments were found effective regarding grain yield and aroma improvements than other levels of nitrogen and water. The head milled rice yield (HMRY) in Nongxiang 18 and Yungengyou 14 was remained than Basmati during both years, whereas the trend for HMRY and 2AP content in mature grain was found as W1 < W2 < W3 and N1 < N2 < N3 for water and nitrogen treatments, respectively. Moreover, the 2AP, 1-pyrroline-5-carboxylic acid content, and pyrroline-5-carboxylic acid synthetase activity were significantly associated with the grain 2AP content at MS. Overall, additional N application at tillering stage with intermittent irrigation could improve rice yield and aroma of fragrant rice.