Abstract
BackgroundWater (W) and nitrogen (N) management generally cause regulations in the 2-acetyl-1-pyrroline (2AP) accumulation in fragrant rice; nevertheless, the feasibility of such management strategies at booting stage in improving 2AP accumulation has not been examined in details.MethodsField experiments were conducted in the early season (March–July) and repeated in the late season (July–November) in 2013. The treatments were applied urea (90 kg ha− 1), calcium super phosphate (90 kg ha− 1) and potassium chloride (195 kg ha− 1) as basal fertilizer, and urea (65 kg ha− 1) at tillering stage. Three N levels i.e., 0 kg N ha− 1 (N1), 30 kg N ha− 1 (N2), and 60 kg N ha− 1 (N3) and three water levels i.e., W1 treatment (well-watered treatment with water layer of 2–4 cm), W2 treatment (soil water potential was − 15 ± 5 kPa), and W3 treatment (soil water potential was − 25 ± 5 kPa) at booting stage was set up for three rice varieties i.e., Nongxiang 18, Yungengyou 14 and Basmati. The grain yield, head milled rice yield, 2AP contents and the biochemical parameters related to 2AP formation were investigated.ResultsResult indicated that W and N dynamics regulated the grain yield, head milled rice yield, and 2AP contents in brown rice across three varieties. The N2 and N3 treatment significantly increased the 2AP contents in brown rice by 9.54% and 11.95%, and 8.88% and 32.54% in the early and the late season, respectively; improved grain yield and head milled rice yield. The W3 treatment improved grain yield, head milled rice yield and 2AP content. Significant W and N interaction effect on 2AP content in brown rice was detected, where the W3 N3 treatment showed the strongest interaction regarding improvement of 2AP contents in brown rice. The 2AP accumulation and its related biochemical parameters and their relationships in different plant tissues at different growth stages under W and N treatments had also been assessed. The 2AP content, P5C content and DAO activity during grain filling periods was highly related to the 2AP content in brown rice.ConclusionThis study revealed that the 60 kg N ha− 1 coupled with − 25 ± 5 kPa treatment showed the best positive effects on yield and aroma in fragrant rice, suggested that water and nitrogen management at booting stage can improve grain yield and fragrance in fragrant rice. However, further study to evaluate the metabolic and molecular basis of 2AP accumulation in fragrant rice is needed.
Highlights
Fragrant rice such as the Pakistani and Indian ‘Basmati’ and Thai ‘Jasmine’ are worldwide famous fragrant rice types among consumers with high trade prices (Sakthivel et al, 2009)
Head milled rice yield and 2AP content Varieties (V) differed significantly regarding grain yield and 2AP content in brown rice in both seasons whereas significant differences among varieties regarding head milled rice yield was detected for late season only
Water (W) showed significant effects on grain yield and head milled rice yield in both seasons, while significant water effect on 2AP content in brown rice was detected for late season only
Summary
Fragrant rice such as the Pakistani and Indian ‘Basmati’ and Thai ‘Jasmine’ are worldwide famous fragrant rice types among consumers with high trade prices (Sakthivel et al, 2009). Many volatile compounds have been detected in fragrant rice, but the 2-acetyl-1-pyrroline (2AP) is considered to be the most important one (Buttery et al, 1983; Buttery et al, 1988; Champagne, 2008; Jezussek et al, 2002). The genetic factor is recognized to play the important role in affecting the aroma biosynthesis in fragrant rice (Lorieux et al, 1996; Bradbury et al, 2008; Fitzgerald et al, 2008), many environmental factors and management practices have been reported to affect the 2AP biosynthesis in fragrant rice (Bhattacharjee et al 2002; Champagne, 2008; Gay et al, 2010; Yang et al 2012; Mo et al, 2016, b). Water (W) and nitrogen (N) management generally cause regulations in the 2-acetyl-1-pyrroline (2AP) accumulation in fragrant rice; the feasibility of such management strategies at booting stage in improving 2AP accumulation has not been examined in details
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