Water scarcity is one of the most important problems of agroecosystems in Mediterranean and semiarid areas, especially for species such as vineyards that largely depend on irrigation. Actual evapotranspiration (ET) is a variable that represents water consumption of a crop, integrating climate and biophysical variables. Actual evapotranspiration models based on remote sensing data from visible bands of Sentinel-2, including Penman-Monteith–Stewart (RS-PMS) and Penman-Monteith–Leuning (RS-PML), were evaluated at different temporal scales in a Cabernet Sauvignon vineyard (Vitis vinifera L.) located in central Chile, and their performance compared with independent ET measurements from an eddy covariance system (EC) and outputs from models based on thermal infrared data from Landsat 7 and Landsat 8, such as Mapping EvapoTranspiration with high Resolution and Internalized Calibration (METRIC) and Priestley–Taylor Two-Source Model (TSEB-PT). The RS-PMS model showed the best goodness of fit for all temporal scales evaluated, especially at instantaneous and daily ET, with root mean squared error (RMSE) of 28.9 Wm⁻² and 0.52 mm day⁻¹, respectively, and Willmott agreement index (d₁) values of 0.77 at instantaneous scale and 0.7 at daily scale. Additionally, both approaches of RS-PM model were evaluated incorporating a soil evaporation estimation method, one considering the soil water content (f_SWC) and the other hand, using the ratio of accumulated precipitation and equivalent evaporation (f_Zhang), achieving the best fit at instantaneous scale for RS-PMS f_SWC method with relative root mean squared error (%RMSE) of 15.2% in comparison to 58.8% of f_Zhang. Finally, the relevance of the RS-PMS model was highlighted in the assessment and monitoring of vineyard drip irrigation in terms of crop coefficient (Kc) estimation, which is one of the methods commonly used in irrigation planning, yielding a comparable Kc to the one obtained by the EC tower with a bias around 9%.

A two-year study was conducted to determine how soil texture affects calcium (Ca) absorption and partitioning in potted ‘Hass’ avocado trees. Trees were planted in 200 L pots in one of four soil types: clay (C), clay loam (CL), sandy loam (SL) or sand (S). Prior to planting, Ca content in each soil was in the normal range of availability, although the Ca concentration was highest in C soil. After two years of tree development, dry weights of shoots and roots were significantly higher in the SL and S soils than in C soil. Trees in the C soil had higher wood dry weight than trees in SL or S soils. The Ca contents (absolute quantities, not concentrations) in the roots, shoots and whole tree were significantly lower in the C soil than in the SL or S soils. The K/Ca ratio of trees in the C soil (K/Ca = 1.5) was significantly higher than that in the other soil types. Stem water potential was significantly lower for trees in the C soil compared to the other soils. These results indicate that Ca absorption and partitioning in young avocado trees varies with soil texture, probably associated with soil effects on root growth and/or plant water status.

Common bean is an important crop, consumed as green-shelled bean in several countries. In Chile, green-shelled beans are cultivated often as a dry land crop, vulnerable to drought. The objective of this study was to characterize the hydric and productive responses of four green-shelled bean genotypes subjected to deficit irrigation in order to outline production strategies in the face of increasing water scarcity. Two experiments were evaluated: one pot experiment with three irrigation treatments, supplying 100% of the crop evapotranspiration (ETc) (T100), 50% (T50), and 30% (T30); and an open field experiment with two treatments: 100% (I100) and 40% of ETc (I40). Treatments were applied during reproductive stage in determinate cultivars and vegetative stage in indeterminate plants. Severe water restriction (T30 and I40) in both experiments showed a significant decrease in stomatal conductances, as well as biomass and number of grains per pod; I40 treatment also showed a reduction in chlorophyll fluorescence. Water use efficiency (WUE) was higher under water stress in field (I40), but lower on the T30 treatment from the pot experiment. Determinate cultivars showed 22.7% higher of 100-seed weight compared to indeterminate type, and, thus, higher tolerance to drought. Our results indicate that severe water stress is highly harmful in terms of yield, and a moderate controlled deficit irrigation plus the use of determinate genotypes may be a strategy for producing green-shelled bean successfully under a drought scenario.

This chapter focuses on the ecophysiology of avocado trees and summarizes the impact of environmental variables including light, temperature, water, salinity, carbon dioxide and pollution on the physiology, growth and development of avocado.