Implementation of deficit irrigation to improve crop water productivity in cantaloupe melons

Abstract Deficit irrigation can enhance crop water productivity (CWP; yield per water applied) but requires careful management to prevent drought-like responses that limit leaf gas exchange (i.e., water-conservative responses) and compromise yield. Grafted and ungrafted melons ( Cucumis melo L.) were evaluated under three irrigation treatments: full irrigation (100% field capacity; FC), and 70% or 50% deficit irrigation, based on water applied to the 100% FC. Although deficit irrigation accentuated drought stress through the season, plants under moderate deficit irrigation (70% FC) had similar water potential (Ψ), and only 34% and 14% lower stomatal conductance ( g s ) and photosynthetic rate ( P n ) than the full irrigation. Under severe deficit irrigation (50% FC), plants had 28% and 17% lower predawn and midday Ψ than the full irrigation. The lower plant water status of the 50% FC resulted in water conservative-responses, and a 65% and 47% lower g s and P n than the 100% FC. Yield of the 100% and 70% FC treatments were affected by evapotranspiration demands (i.e., irrigation × year interaction), while the 50% FC had a 40% lower yield than the full irrigation. Moderate deficit irrigation reduced water applied by 25%, and had either a similar or a 47% increase in CWP compared to the full irrigation. Overall, grafting improved yield by 14%, but it was greater under full irrigation and low environmental stress. Overall, melon crop performance was maintained under a constant, moderate deficit irrigation, and this should be considered as an effective water-saving strategy for melons to cope with long-season droughts.