Suitability of soybean, cowpea and quinoa for conditions of climate change in the Vietnamese Mekong Delta dry season

Background Saline intrusion and freshwater scarcity is occurring across regions of the Mekong River Delta Vietnam which is driving the need to identify suitable alternative crops that are fast maturing, water efficient and/or saline tolerant. Methods A glasshouse trial examined the suitability of quinoa ( Chenopodium quinoa Kruso white), cowpea ( Vigna unguiculata Red Caloona) or soybean ( Glycine max Richmond) for growth in regions affected by salinity and drought. Plants were irrigated with either fresh or saline (up to 4 g L ^− 1 ) water. Chameleon soil moisture sensors were used to trigger irrigation events, either constantly (water potential 0 to -22 kPa) or intermittently (irrigating when the water potential was <‒50 kPa). Results Saline treatments significantly affected the yield of all three species; however, quinoa grew in saline conditions for the longest duration. Cowpea was negatively affected by intermittent irrigation causing decreased yield higher proline concentrations in younger leaves. Quinoa had the lowest daily water use whilst soybean had the highest daily water consumption. Cowpea and quinoa tolerated irrigation with 4 g L ^− 1 during reproductive phases, whilst soybean experienced leaf chlorosis and premature senescence with saline irrigation. Conclusion Quinoa may be suitable for growth in saline and water limited affected areas of the MRD, soybean suitable for areas where saline intrusion or freshwater scarcity is not a problem, and cowpea suitable for saline affected areas provided irrigation supply is available to match plant demand. Chameleon sensors can improve water use and be used to aid farmers in developing irrigation schedules.