Effect of Planting Density and Irrigation Management on the Growth, Yield, and 2-acetyl-△1-pyrroline Content of Fragrant Rice

Fragrant rice has excellent rice quality and considerable economic benefits. There are few reports on planting density and irrigation management on the yield and 2-acetyl-△1-pyrroline (2-AP) content of fragrant rice. In this study, 2 planting densities (3–4 and 6–7 seedlings hills −1 ) and 3 irrigations (farmers’ irrigation practice with mid-season drainage (FP), alternate wetting and drying irrigation (AWD) at the − 15 cm (AWD15), and − 25 cm (AWD25) threshold level for irrigation managements) were adopted to investigate the effects of planting density and irrigation management on growth, yield, 2-AP, synthetic precursors, and enzymes involved in 2-AP formation. The results showed that dry weight (DW), leaf area index (LAI), panicle number, and yield as well as the content of 2-AP, synthetic precursors, and enzymes activities involved in 2-AP biosynthesis increased in high-density. Compared with FP, AWD15 increases N concentration of leaves, LAI, net photosynthetic rate (Pn), seed setting rate, and 1000-grain weight, yet it has no effect on yield. Although AWD25 has a better effect on enhancing 2-AP, AWD25 reduces DW, LAI, Pn, yield, and yield components. Our results illustrated that 6–7 seedlings hills −1 and AWD15 are the superior water-saving methods for fragrant rice to increase the content of 2-AP and maintain yield.