Differential Effects of Deficit Irrigation and Reflective Mulch Application on Two Clingstone Peach Cultivars

The effect of deficit irrigation and reflective mulch on fruit quality of clingstone peach cultivars ‘Loadel’ and ‘Fortuna’, which ripen during the second half of July, was studied during 2007. Four treatments were applied for each cultivar: 1) control (C), irrigation applied at 160% of evapotranspiration (ETc); 2) deficit irrigation, irrigation at 75% of ETc in the last three weeks before harvest; 3) reflective mulch Extenday® underneath the tree canopy on the tree row applied three weeks before harvest; and 4) the combined treatment of reflective mulch and deficit irrigation. Quality was assessed with fruit harvested at commercial maturity from throughout the canopy of the experimental trees. The fruit quality parameters measured included: skin color; firmness, specific conductivity and percent dry mass in the flesh; and acidity, soluble solids content, and total phenolic content in fruit juice. In addition, solar radiation (UV and PAR) underneath the tree canopy was measured. The reflective mulch significantly increased reflected UV and PAR to the lower canopy of peach trees compared to the reflected light from the soil underneath the control trees. Deficit irrigation of 'Fortuna' peaches delayed ripening with overall reduction in fruit quality compared to control peaches. In the same cultivar, reflective mulch combined with excessive or deficit irrigation did not affect fruit quality compared to control, but had improved quality compared to fruit from deficit irrigated trees. In contrast, 'Loadel' peaches of deficit irrigated or reflective mulched trees and their combination treatment had better quality (or advanced maturity) compared to fruit from control trees.