Yield and quality of potato tuber and its water productivity are influenced by alternate furrow irrigation in a raised bed system

Scarcity of irrigation water has now become the main constraint for crop production globally. Irrigation water scarcity becomes severe especially during the dry, winter season in South Asia, particularly in Bangladesh due to the decline in groundwater table and drying of surface water resources. In South Asian countries, potato is traditionally grown with furrow irrigation system in dry, winter season in which irrigation water is applied frequently to each and every furrow. Such irrigation method increases water use and lowers irrigation water productivity (WP). We hypothesized that potatoes grown on raised beds, and irrigation water applied to alternate furrows based on the principle of partial root-zone drying, would maintain yield, reduce water use and increase WP, and enhance the quality of potato tubers in drought-prone areas of South Asia. To test this hypothesis, an experiment was conducted in two consecutive dry, winter seasons (2015-16 and 2016-17) at the research field of Irrigation and Water Management Division of the Bangladesh Agricultural Research Institute, Gazipur, Central Bangladesh and assessed crop dry matter and yields, water use and WP, quality, and nutrient concentrations of potato tubers in different irrigation treatments. The experiment consisted of two levels (first, three irrigation at critical growth stages and second, four irrigation at every 12-15 days interval) and three methods (AFI - alternate furrow irrigation; FFI - fixed furrow irrigation; and EFI - every furrow irrigation) of irrigation. Dry matter and tuber yield of potato did not differ significantly (P < 0.05) between AFI and EFI but differed significantly (P < 0.01) when compared to FFI. On average, AFI and EFI had tuber yield of 21.9 and 22.2 t ha(-1) with three irrigation and 23.2 t ha(-1) and 23.9 t ha(-1) with four irrigation, respectively during 2016 and 2017 while AFI and EFI had WP of 14.8 kg m(-3) and 9.89 kg m(-3) with three irrigation and 14.9 kg m(-3) and 9.96 kg m(-3) with four irrigation, respectively during 2016 and 2017. On average, AFI saved irrigation water by 35% and irrigation water productivity significantly (P < 0.001) improved by 50% compared to EFI over two years. Total soluble sugar, as an indicator of tuber quality, also varied significantly (P < 0.01) between AFI (6.29(0) Brix) and EFI (6.37(0) Brix). Nutrient concentrations of potato tubers were not significantly different (P < 0.05) between irrigation treatments. Results demonstrate that the alternate furrow irrigation can maintain potato tuber yield, and reduce water use and increase irrigation water productivity of potato tubers compared to every or fixed furrow irrigation in Bangladesh. This irrigation method could potentially be an attractive alternative to every or fixed furrow irrigation in South Asian countries where irrigation water is limited and appropriate water-saving irrigation methods are not available.