Sap Flow Scaling and Crop Coefficient of Dry-Farmed Olive Orchards Converted to Irrigation

Abstract

Tree water uptake is often estimated based in a crop coefficient k c , a ratio of the tree water uptake and a reference evapotranspiration, ET0. The concept behind estimating tree crop coefficient implies that data should be representative of the population of trees analyzed. Ideally it would require the monitoring of a large number of trees in each treatment population. This paper reports on a scaling method to establish stand-level transpiration estimates and crop coefficients from individual sampled tree sap flow measurements. The scaling technique was implemented for individual tree sap flow measurements on the following irrigation treatments: A, fully-irrigated; B, irrigated to provide for approximately 60% of crop evapotranspiration; C, irrigated to provide for 100% of crop evapotranspiration during three critical phase periods: before-flowering, at beginning of pit-hardening and before crop-harvesting, and dry-farming treatment D. Results show that stand transpiration T depart from individual tree transpiration values. They consequently were used to establish crop, k c and water stress, k s coefficients to account for the cluster's characteristics and degree of tree's water uptake. Using the individual tree transpiration rates would be less appropriate.

Quantifying the vertical water exchange of dominant tree species in a reclaimed landscape in the Athabasca oil sands region, Alberta

“…Total cumulative volume water use per species (L) was summed for each subplot and converted to mm day À1 following a series of conversions similar to Langs et al (2021). In brief, once the daily regressions are applied to the tree survey and daily flows were summed (L day À1 ), T was converted to ground area by dividing by the total sampled area of the tree survey (m 2 ) (Santos et al, 2012). Total daily T was converted to a depth (mm day À1 ) and averaged per plot and then across the study area.…”

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF OLIVE (Olea europaeaL.): A REVIEW

“…In the well-irrigated trees the T/ETo ratios declined over the summer months from 0.75–0.8 in March/April to 0.6 in June/July, before increasing to 0.9 in September. This reflected the effect of the high-potential ETo (=7–8 mm d −1 ) experienced in mid-summer, which exceeded the capacity of the trees to transfer water from the wet soil to the sites of evaporation in the leaf at the needed rate (Santos et al ., 2012). The implications of the results of this experiment in terms of yield are considered below.…”

Evapotranspiration Partition and Dual Crop Coefficients in Apple Orchard with Dwarf Stocks and Dense Planting in Arid Region, Aksu Oasis, Southern Xinjiang

“…Direct measurement methods in the field can obtain ET a , such as water balance method [9,10], lysimeters [8], sap flow measurements [11][12][13] and eddy covariance [10,[14][15][16], and by crop evapotranspiration modelling, e.g., SIMDualKc [7,14,15,17,18], HYDRUS [19], Crop-Syst [8], and remote sensing information [20,21]. The FAO crop coefficient procedure, classified as single coefficient and dual coefficients, is one of the most common methods for determining ET a [22].…”

“…Meanwhile, the rainfall intercepted by plant canopy accounts for 20 ± 8% of the total global rainfall [25]. Crop coefficients of woody plants in different regions have been reported by researchers, such as olives in Portugal [12,15,18,20,23], apples in Spain [8], Italy [16], Chile [21], North China [6,24,[26][27][28] and South Africa [13,29], pears in Portugal [14,17,30], citrus in India [10], and pecan in southwestern USA [31]. Although several apple crop coefficient results were reported, the dual crop coefficients and evapotranspiration components of the DCHD orchards are limited, especially for the DCHD apple orchards in extremely arid regions.…”