Five‐Year Observations on Scion–Rootstock Combinations of Peach Under Mild and Severe Deficit Irrigation in Warm Area

ABSTRACT With new trends for intensification, questions on the sustainability of irrigated agriculture and efficient water demand management need to be investigated under water shortage. A field experiment was conducted to improve water management of peach orchards in Northern Tunisia. An early peach cultivar grafted on GF677 and Cadaman was subjected to mild (DI 1 ) and severe (DI 2 ) deficit irrigation in a public irrigation network with poor reliability of supply. Tree and soil water status, yield, fruit quality and water productivity (W p ) were investigated. Tree water status under contrasting water supply was affected by rootstock. Lower predawn (Ψ PD ) and stem (Ψ stem ) water potentials were observed on less vigorous Cadaman. Ψ PD and Ψ stem were linearly correlated with each other and with soil water content and water supply index K s (as ratio [Irrigation + Precipitation]/ET o ). Fruit yield and W p were significantly reduced with DI 2 for both rootstocks. Lower yields were also obtained in the warmest year. In conclusion, Ψ stem and K s could be considered as valuable tools for deficit irrigation scheduling with threshold values established for DI 1 and DI 2 with adjustment according to rootstock type. Low‐chill cultivar with vigorous rootstock and mild deficit seemed to be the best solution in warm areas under water scarcity.