Irrigation Factor Approach Based on Soil Water Content: A Nectarine Orchard Case Study

Abstract

Precision agriculture requires irrigation supported by an accurate knowledge of the crop water requirements. In this paper, a novel approach for drip irrigation scheduling of fruit trees is presented based on the results obtained during a full growing season in an early-maturing nectarine orchard growing in a clay loam soil in a Mediterranean environment. Real-time water content was monitored in the soil profile of the main root exploration zone by means of capacitance probes; in addition, plant water status (midday stem water potential and leaf gas exchange) and canopy development were frequently measured throughout the vegetative cycle. The reference evapotranspiration (ET0) values, taken from a nearby automatic meteorological station, and the measured irrigation values allowed the determination of the irrigation factors once irrigation drainage during the season was assumed to be negligible and plant water status was proved to be adequate. The proposed irrigation factors offer a hands-on approach as an easy tool for irrigation management based on suitable soil water deficits, allowing the water requirements of nectarine trees under precision irrigation to be determined in semi-arid agrosystems where water resources are limited.

Trends and Challenges in Irrigation Scheduling in the Semi-Arid Area of Spain

“…VSWC-based treatment induced moderate water deficits in peach trees as indicated the lower Ψ stem values (up to −1.5 MPa) compared with the control trees (around −0.8 MPa) during the postharvest period [117,120]. Ψ stem values for nectarine trees remained around −1 MPa in both treatments [123].…”

“…For stone fruit tress under drip irrigation, the values α = 0.1 MAD during the critical period (fruit growth and early postharvest) and α = 0.3 MAD during late-postharvest were applied ( Figure 2). This approach was studied in a nectarine orchard (with a similar phenology calendar as in peach) with the aim of fulfilling plant water requirements [123]. irrigation only started if the SWC in the top 0.5 m layer at this time was below 95% of field capacity (FC) and stopped when the sensor at 0.8 m depth showed an increase of 2% over its value recorded at 22:00 h. This procedure induced a "divergent pattern" on VSWC with a progressive decrease in VSWC at 0.8 m, with increasingly higher levels needed before reaching the target.…”

Terrestrial and Remote Indexes to Assess Moderate Deficit Irrigation in Early-Maturing Nectarine Trees

“…A non-flat pattern of the Ψ stem in both irrigation treatments reflected the climatic demand ( Figure 2A), with decreasing values from May onwards. In control trees, mean Ψ stem was −0.82 MPa ( Figure 3A), which is characteristic of well-watered nectarine trees [3,51,52], whereas in the PDI treatment Ψ stem values were on average 0.25 MPa lower with respect to control trees, this difference being statistically significant from mid-July onwards. A minimum Ψ stem value of −1.7 MPa was reached in September in the PDI treatment ( Figure 3A).…”

“…Efficient irrigation of horticultural crops using technologies that enable the better husbandry of scarce freshwater resources has been increasingly studied in recent years, because irrigated agriculture is the largest user (up to 70%) of freshwater worldwide [1]. This situation might worsen in coming years as the world's population is expected to increase by 30% by 2050 coupled with forecasted climate change and competition with urban, touristic, and industrial activities [2,3].…”

Leaf Water Relations in Lime Trees Grown under Shade Netting and Open-Air

“…The trees were irrigated to fulfil plant water requirements throughout the experiment. The irrigation scheduling was automated with soil management that allowed depletion (MAD) of 10% [52]. The soil water content was monitored at a depth of 0.8 m by means of multi-depth capacitance probes (EnviroPro ® , Entelechy Pty.…”