Does Partial Rootzone Drying Alternation Frequency Enhance Water Stress Resistance and Improve Water Saving?

The objective of the work was to assess if the variation of alternation frequency when applying partial rootzone drying irrigation strategy (PRD) does affect tomato crop water shortage resistance and water use efficiency (WUE). Hence, physiological responses in terms of stomatal conductance, maximum daily shrinkage (MDS), root initiation were monitored and water use efficiency was determined. Three treatments were applied: a control (T0) and two PRD treatments. The control received 100 % of tomato crop water requirements (ETc) whereas PRD50-20 and PRD50-40 were both irrigated at 50 % of ETc. PRD50-20 was alternated at 20 % of rootzone dry side water storage depletion while PRD50-40 was alternated when the water storage within rootzone dry side decreases by 40%. PRD treatments showed a decrease in leaf stomatal conductance while the control was characterized by the highest stomatal conductance levels. In addition, PRD50-20 registered higher values than PRD50-40 showing that the later restrict more its water loss. Stem diameter micro-variation results corroborated previous finding since PRD50-20 registered higher MDS than PRD50-40. Besides, when compared to T0, root initiation was enhanced by 78 % and 32 % for PRD-5040 and PRD50-20, respectively. In terms of water use efficiency (WUE), PRD treatments registered higher values than the control (61g/l) and PRD50-40 (84g/l) performed better WUE than PRD50-20 (73g/l)