Early Navel Orange Fruit Yield, Quality, and Maturity in Response to Late-season Water Stress

Abstract

The objective of this study was to measure effects of late-season water stress on fruit yield, size, quality, and color of an early-maturing navel orange cultivar, Citrus sinensis (L.) Osbeck ‘Beck-Earli’. Three irrigation regimes were initiated in August in the southern San Joaquin Valley of California in 2006, 2007, and 2008. Increasing levels of water stress resulted in decreasing midday shaded leaf water potential (SLWP) ranging from –1.4 MPa in early September to a minimum of –2.5 MPa at harvest. Generally, over the course of the 3 years, late-season water stress decreased fruit grade and increased soluble solids concentration (SSC), titratable acidity (TA), the BrimA index, and orange color. Fruit juiciness and SSC:TA ratios were unaffected by late-season water stress. The intensity of the water stress in 2007 decreased fruit yield by number and weight and decreased the percentage of large fruit. When trees exposed to 2 years of late-season water stress were fully irrigated the next year, fruit yield and quality were similar to trees that had not experienced late-season water stress for the 3 years of the study.