Modeling photosynthesis in olive leaves under drought conditions

Abstract

We quantified parameters for a model of leaf-level photosynthesis for olive, and tested the model against an independent dataset. Specific temperature-dependence parameters of the model for olive leaves were measured, as well as the relationship of the model parameters with area-based leaf nitrogen (N) content. The effect of soil water deficit on leaf photosynthesis was examined by applying two irrigation treatments to 29-year-old trees growing in a plantation: drip irrigation sufficient to meet the crop water requirements (I) and dry-farming (D). In both treatments, leaves had a higher photosynthetic capacity in April than in August. In August, photosynthetic capacity was lower in D trees than in I trees. Leaf photosynthetic capacity was linearly and positively related to leaf N content on an area basis (N(a)) and to leaf mass per unit area (LMA), and the regression slope varied with irrigation treatment. The seasonal reduction in N(a) was used in the model to predict photosynthesis under drought conditions. Olive leaves showed a clear limitation of photosynthesis by triose phosphate utilization (TPU) even at 40 degrees C, and the data suggest that olive invests fewer resources in TPU than other species. The seasonal decrease in photosynthetic capacity moderated the stomatal limitation to carbon dioxide (CO(2)) fixation as soil water deficit increased. Further, it enabled leaves to operate close to the transition point between photosynthetic limitation due to RuBP carboxylation capacity and that due to RuBP regeneration capacity, and resulted in a near constant value of internal CO(2) concentration from April to August. Under well watered conditions, N-use efficiency of the olive leaves was enhanced at the expense of reduced water-use efficiency.

Plant-Based Methods for Irrigation Scheduling of Woody Crops

“…When working with a species for which the daily dynamics of gs are unknown, daily curves of gs must be previously made to assess the time of the day at which gsmax must be measured [32]. In addition, information on the optimal environmental conditions leading to maximum potential gs values is valuable for properly assessing the meaning of field gsmax measurements [33]. Figure 2.…”

Long-term acclimation of mesophyll conductance, carbon isotope discrimination and growth in two contrasting Picea asperata populations exposed to drought and enhanced UV-B radiation for three years

“…For instance, leaf N is correlated with leaf photosynthetic capacity, and both of them are often correlated with SLA (Díaz-Espejo et al, 2006;Feng, 2008). However, most of the above-cited papers have dealt with simple bivariate relationships.…”

Determining Evapotranspiration in an Olive Orchard in Southwest Spain

“…We used the K c values determined by Fernández et al (2006) for the orchard conditions (0.76 in May, 0.70 in June, 0.63 in July and August, 0.72 in September and 0.77 in October). The value of the coefficient related to the percentage of ground covered by the crop (K r ), calculated after Fereres and Castel (1981), was 0.71.…”

“…From the θ values we calculated the relative extractable water (REW) of the soil as REW = (R -R min )/(R max -R min ), being R (mm) the actual soil water content, R min (mm) the minimum soil water content measured during the experiments, and R max (mm) the soil water content at field capacity (Granier, 1987). The leaf area (LA, m 2 one side) of the three trees in which θ was measured was estimated as described by Fernández et al (2006). Half-hour values of the main meteorological variables were continuously recorded by an automatic weather station next to the olive orchard.…”

“…The Orgaz et al (2005) method was used to develop a user-friendly Excel application intended to calculate crop water requirements in commercial orchards, which was delivered with the book by Pastor et al (2005). Our aim was to evaluate the method by Orgaz et al (2005) in an olive orchard representative of the commercial orchards in the Aljarafe county, the main production Palomo et al (2002) show that the K c values suggested by Fernández et al (2006) are reasonably precise for our orchard conditions. In addition, we compared the E p Orgaz values with the E p sim values.…”