Effects of the application of a moderate alternate wetting and drying technique on the performance of different European varieties in Northern Italy rice system

Alternate wetting and drying (AWD) technique has been developed and evaluated on rice ( Oryza sativa ) systems in several countries worldwide for increasing water use efficiency and reducing negative effects of permanent flooding, like the increase in methane emissions and arsenic availability in soil. In this study, a paddy field experiment was carried out for two years to evaluate the application in Northern Italy rice area of a moderate AWD, i.e. only implemented during the vegetative phase of the crop and ponded water maintained thereafter, compared with Continuous Flooding (CF) system. The adaptability of 12 European commercial rice cultivars to AWD was investigated in terms of crop phenology, morphological traits, root production, nitrogen (N) uptake, yield, milled rice yield and microelement concentration in grains. Results showed substantial (40.7%) water saving probably favoured by the presence of a shallow water table. In these pedoclimatic conditions, very limited effects of a mild AWD on crop status and final productivity were recorded and the commercial cultivars did not display significant different adaptabilities to the water stress. Moreover, AWD
decreased arsenic (As) concentration in grain but increased grain Cadmium (Cd) being the degree of such a response dependent upon the variety, suggesting that the genotype plays an important role in this aspect of adaptation to AWD.