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Submitted to: Journal of Agricultural Studies
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/6/2015 Publication Date: 9/26/2015 Citation: Wang, D. 2016. Water use dynamics of peach trees under postharvest deficit irrigation. Journal of Agricultural Studies. 4(1):34-54. Interpretive Summary: For early season tree crops, postharvest deficit irrigation or applying water to less than the full evapotranspiration needs may be used to save water. Field experiments were carried out in a peach orchard in three growing seasons to determine evapotranspiration and crop coefficient characteristics under deficit irrigation as compared to full irrigation conditions. Results showed that the peak crop coefficient values under deficit treatment was reduced from the full irrigation scenarios and the findings are valuable for potentially using pre-determined deficit crop efficient values to manage deficit irrigation practices to increase agricultural water use efficiency. Technical Abstract: Postharvest deficit irrigation is a potential strategy for conserving valuable fresh water for production of early season tree fruit crops such as peaches. However, behaviors of evapotranspiration characteristics and crop coefficient (Kc) under deficit irrigation conditions are largely unknown. A three-year field study was carried out in a 1.6 ha peach orchard to determine evapotranspiration characteristics and compare Kc values under deficit irrigation conditions with non-water stressed conditions. A Bowen ratio flux tower was installed to make measurements for estimating actual crop evapotranspiration (ETc) in the orchard where some areas received deficit irrigation. The study showed that from July to August 75-85% of the daily net radiation was used by latent heat or partitioned into ETc. The average monthly cumulative ETc was 151 mm in June, 162 mm in July, and 155 mm in August. Kc values under deficit irrigation conditions or termed as Deficit_Kc was computed as ratios of the ETc over potential evapotranspiration or ETo, and were compared with Kc derived from a lysimeter study under non-water stressed conditions or termed as Lysimeter_Kc. The maximum Deficit_Kc values were 0.90, 1.03, and 1.07 for the three field seasons but all were smaller than 1.20, the maximum Lysimeter_Kc. The study demonstrated that water stress under deficit irrigation can be characterized in Kc values. The approach may be used to provide guidance on deploying deficit irrigation practices with pre-determined Deficit_Kc. |
