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.