Spring deficit irrigation in olive (cv. Genovesa) growing under arid continental climate: Effects on vegetative growth and productive parameters

Abstract

This study was aimed to evaluate theeffect of regulated deficit irrigation (RDI), applied from mid-spring to earlysummer, on physiological parameters, vegetative growth and productivity in anintensive hedgerow olive orchard located in a non-traditional (marked winter-spring water-deficit) olive growing region. The experiments werecarried out during three crop seasons by using four years old (7 m × 3.5 m)?Genovesa? olive trees. Three RDI treatments (T25, T50 and T75)were applied as a percentage of crop evapotranspiration (25, 50 and 75 % ETc,respectively) during the period from fruit set to pit hardening. Also, a control treatment was irrigated at 100 %ETc during the whole crop season. Under the analyzed environmental conditions, stomatalconductance wasless sensitive in young leaves than in mature leaves against changes in water availability.This fact should be considered when being used as benchmarks in olives treessubmitted to water deprivation during periods with marked water constraint.Regarding vegetative parameters, significant reductions in apical vegetative shoot growth, trunk cross-sectionalarea and canopyvolume were found in less irrigated treatments (T25 and T50) with respect to most irrigated ones (T75 and T100). Moreover, the strongest effects of deficitirrigation were observed when pruning was applied at the end of the second cropseason evaluated. Both fruit and oil yields were barely affected by wateravailability. Althoughin the first crop season evaluated the fruit yield was greater in the full-irrigationtreatment ? which could be due to the age of the olive trees -, at the end ofthe whole experimental period (three crop years) the mean values from thisyield component did not present significant differences among all irrigationtreatments. Similarly, water availability did not affect oil yield (kg/ha); nosignificant differences were found among irrigation treatments in any of thecrop seasons analyzed. The effects of water availability on productive parameters were moreevident when analyzed as an estimated productive response; the irrigation waterproductivity, calculated on both fruit weight and oil weight bases, gave the highest values in themost restrictive irrigation treatment. Overall, findings from this study couldbe of interest for olive cultivation in regions with dry spring period and for intensivehedgerow orchardssuited to over-rowharvesters. Imposing water restriction during this period could be suitable for achieving sustainable fruit and oilproductivity while saving considerable amount of irrigation water.