Abstract
Arbuscular mycorrhizal fungi (AMF) provide host plants with water and nutrients. Here, we investigated the response of six rice varieties from two ecotypes (three irrigated and three rainfed upland varieties) to inoculation at five fertilizer levels, under continuous flooding (CF) and alternate wetting and drying (AWD) irrigation in field conditions in two consecutive years. For both irrigated and upland rice, the application of AWD irrigation and reduction in NPK fertilizer levels resulted in significant yield losses, with a greater magnitude for irrigated rice. Under AWD irrigation, inoculation with AMF reduced relative yield losses with a more pronounced effect at half recommended dose of fertilizer. Under CF, the yield losses related to reduction in NPK fertilizer levels were often fully offset by inoculation with AMF. On the other hand, irrigation regime, fertilizer level and ecotype were identified as significant sources of variation in mycorrhizal inoculation effect for many yield-related traits including, total biomass, tiller number, panicle number, fertility and maturity dates. Our results suggest that inoculation with AMF could be associated with AWD irrigation and/or low NPK inputs to contribute to mineral fertilizer and water saving in both irrigated and upland rice production systems.