Growth, yield and water productivity of selected lowland Thai rice varieties under different cultivation methods and alternate wetting and drying irrigation

Abstract

Development of water‐saving techniques for irrigated lowland rice production system is a requirement in the context of increasing irrigation water scarcity. A pot experiment was conducted to evaluate the performance of selected lowland Thai rice varieties grown under different cultivation methods subjected to alternate wetting and drying (AWD) irrigation. Treatments consisted of three varieties (Pathumthani 1, RD57 and RD41), three cultivation methods (dry direct seeding [DDS], wet direct seeding [WDS] and transplanting [TP]) and four AWD irrigation levels (re‐watered when soil water potential reached at 0, −5, −15 and −30 kPa). DDS resulted in higher grain yield at −5 and −15 kPa (74 and 68 g/pot, respectively) with a respective reduction of 15 and 34% under WDS and TP at −5 kPa, and 15 and 28% at −15 kPa. The highest water productivity was recorded at −30 kPa under DDS, which was reduced by 17–61% for other soil water potentials irrespective of varieties; however, grain yield was also reduced by 12–19% at −30 kPa. All varieties responded similarly to water‐saving techniques (direct seeding and different levels of AWD) with non‐significant differences in grain yield and water productivity; therefore, could be recommended to grow these varieties using water‐saving techniques. The optimum threshold level of AWD could be −15 kPa for its high grain yield and water productivity.