The response of field-grown mango (cv. Keitt) trees to regulated deficit irrigation at three phenological stages

Abstract

The objective of the current study was to examine the effect of different irrigation levels at different phenological stages on fruit yield, fruit size, vegetative growth, and subsequent season crop yield of mango trees growing in sub-tropical weather conditions. Three independent experiments were conducted in parallel in three phenological stages: main fruit growth (MFG)—from fruit set to pit hardening; final fruit growth (FFG)—from pit hardening up to harvest; and post-harvest (PH)—after harvest until the first meaningful rain. Each experiment was consisted of four irrigation levels that were determined as crop coefficients of Penman–Monteith evapotranspiration. Differential irrigation levels were applied in each phenological stage, where commercial irrigation levels were applied in the rest of the season. Crop yield in the MFG stage was unaffected by the irrigation treatments. The number of fruit in the MFG stage increased slightly with increasing water quantities. Average fruit size in the MFG stage decreased with increasing the number of fruit per tree, indicating that the number of fruit rather than irrigation regime is the main determinant of the final fruit size. The number of fruit per tree in the FFG stage was unaffected by the lowest irrigation treatment; however, the same treatment had the lowest fruit size, significant only in 2013. Post-harvest shoot growth in the FFG stage experiment increased with irrigation level (significant in 2013), indicating that water stress in the FFG stage had a carryover effect. The crop yield in the PH stage increased with increasing irrigation rate in the former season, significant in 2011 and 2013. The higher yields in the high irrigation treatments in the PH stage were associated with larger fruit size. The number of post-harvest vegetative flashes increased with increasing crop coefficient (K c) in the PH stage in the same season, except for the 2011. Crop yield in the PH stage increased with increasing number of post-harvest vegetative flashes in the former season. The results obtained in the current study indicate that the mango in Israel is sensitive to deficit irrigation in both the FFG in an “ON” season and in the PH stage towards an “ON” season.