Comparative performance of direct seeded rice and transplanted rice under different irrigation regimes

Abstract:

Direct seeded rice (DSR) is promoted as a water-saving alternative to conventional transplanted rice (TPR), but its yield stability across irrigation regimes in temperate maritime climates remains poorly documented. This research compared DSR and TPR under three irrigation levels—continuous flooding (CF), alternate wetting and drying (AWD), and deficit irrigation (DI)—at the Royal Highland Institute of Agriculture, Edinburgh, during the 2023 growing season. A split-plot design with irrigation as the main plot and establishment method as the subplot was replicated four times. TPR under CF produced the highest grain yield (5.48 t ha⁻¹), while DSR under DI gave the lowest (3.89 t ha⁻¹). However, DSR under AWD (4.67 t ha⁻¹) was statistically comparable to TPR under the same regime (5.21 t ha⁻¹) while using 23.4% less total water. Water productivity was highest for DSR-AWD at 0.84 kg m⁻³ versus 0.59 kg m⁻³ for TPR-CF. Tiller counts and panicle number were lower in DSR, but individual grain weight was heavier, partially compensating for reduced panicle density. These results suggest that DSR combined with AWD irrigation can be a practical water-saving option for rice production in temperate UK conditions, provided that weed management during early establishment is adequate.