Water use, transpiration, and crop coefficients for olives (cv. Cordovil), grown in orchards in Southern Portugal

Abstract

To improve the scheduling of irrigation for low-density olive trees (Olea europaea L.) grown in a typical Mediterranean environment of Southern Portugal, and to clarify the mechanisms of water uptake by trees, transpiration, soil water status and stomatal response to water deficit were measured in an olive orchard. Olive trees of cv. Cordovil were subject to three irrigation treatments: full-rate irrigation, sustained deficit irrigation (SDI) providing for approximately 60% of water applied at full-rate irrigation, and a regulated deficit irrigation (RDI) with water applied at periods during three critical phases: before-flowering, at beginning of pit-hardening, before crop-harvesting to replenish soil moisture to field capacity. There was also a dry-farming treatment. Trees responded differently to summer rainfall and irrigation water: full-rate irrigation, which received 880 mm of irrigation and 240 mm of rainfall, used 704 mm for transpiration; SDI, which received the same amount of rainfall and 448 mm of irrigation water, used 745 mm of water for transpiration; RDI, which received 69 mm of irrigation water and 240 mm of rainfall, used 638 mm of water for tree transpiration; dry-farming, which received no irrigation, benefited from 240 mm of summer and early autumn rain and used 404 mm of water for transpiration. The results support the hypothesis that trees under RDI and dry-farming satisfy most of their early atmospheric evaporative demand by extracting water from outside of the area wetted by drip irrigation. Scaled-up orchard transpiration was used to define orchard crop and water stress coefficients. With full-rate irrigation and SDI the results showed that during summer droughts olive trees slow down their physiological mechanisms to conserve water, regardless of amount applied. The derived crop coefficient results also indicated that SDI was the most appropriate for scheduling the irrigation of cv. Cordovil orchards in Southern Portugal although applying RDI helped sustain orchard transpiration and yields. Irrigation accounted for 11% of total water used in transpiration, with the balance extracted by roots in the large volume of soil lying in the areas between the trees. However, using the RDI scheme to schedule irrigation appears to be appropriate only in wet years with well distributed late summer rainfall or where there is a shortage of farm irrigation water. In general, and particularly in years with no summer and early autumn rains as can often occur in this region, the SDI regime appears to be more appropriate for scheduling irrigation.

Ecological impacts of early 21st century agricultural change in Europe – A review

“…In Portugal, the loss of economic value of traditional arable systems, coupled with the increasing demand for Mediterranean products such as olive oil and wine, is resulting in large-scale conversion of open arable and pastoral landscapes into vineyards and intensive, irrigated olive orchards with densities up to 1700 trees ha À1 (Ramos and Santos, 2009). This conversion is considered a major threat for open farmland specialists.…”

Evapotranspiration and crop coefficients for a super intensive olive orchard. An application of SIMDualKc and METRIC models using ground and satellite observations

“…Various studies have been developed with derivation of crop coefficients for olive orchards but with results largely varying with management (e.g., Villalobos et al, 2000;Ramos and Santos, 2009;Er-Raki et al, 2010;Cammalleri et al, 2013). Thus, the adjustment of crop coefficients is required taking into consideration planting density and vegetation height.…”

Effects of Land Use Intensification on Fish Assemblages in Mediterranean Climate Streams

“…However, in recent decades the region has experienced a more accelerated change in farming systems, due to the expansion of more profitable irrigated agriculture (Pinto-Correia and Vos 2004). Increased demand for products such as olive oil and wine has resulted in a significant conversion of open arable land to permanent and intensive uses such as vineyards and irrigated olive groves (Diogo and Koomen 2010;Ramos and Santos 2009).…”