Long-term performance of ‘Valencia’ sweet orange grafted onto nine rootstocks under two subtropical environments in Brazil: Effects of orchard age on growth, yield, fruit quality, and planting estimates

• Rootstock × location interaction modulated tree growth, yield, and fruit quality. • Trees on ‘Carrizo’ and ‘Swingle’ showed high yields and stable performance over 17 years. • ‘Trifoliate’ reduced tree size, improving planting density and yield efficiency. • Paranavaí favored early yield while Londrina enhanced vegetative growth and late stable yields. • ‘Carrizo’ and ‘Swingle’ produced fruit with high juice content and TSS yield. ‘Valencia’ sweet orange is a cornerstone of the global citrus industry, widely cultivated for both juice-processing and fresh fruit markets. Rootstock selection plays a critical role in determining long-term tree performance, yet comparative multi-environment studies spanning different orchard ages remain limited. This 17-year field trial (2000–2017) evaluated the horticultural performance of ‘Valencia’ trees grafted onto nine rootstocks – ‘Rangpur’ lime, ‘Swingle’ citrumelo, ‘Volkamer’ lemon, ‘Caipira DAC’ orange, ‘Cleopatra’ and ‘Sunki’ mandarins, ‘Trifoliate’ orange, ‘Carrizo’, and ‘Fepagro C-13′ citranges – at two contrasting locations in Paraná, Brazil (Londrina and Paranavaí). Trees were assessed over three orchard maturity phases: establishment (3–7 years old trees), full production (8–13 years), and aging (14–17 years; evaluated in one location only). Vegetative growth, yield performance, fruit quality attributes, and estimates of planting density, productivity, and total soluble solids (TSS) yield were evaluated over time. Data were analyzed using mixed-effects models for each orchard age, based on a randomized block design structured as a 9 × 2 factorial arrangement (rootstock × location), with six replicates and four trees per plot. ‘Cleopatra’ induced vigorous tree growth across the orchard’s lifespan, while ‘Trifoliate’ reduced tree size of ‘Valencia’, enhancing yield efficiency and supporting higher planting density. ‘Carrizo’, ‘Swingle’, and ‘Fepagro C-13′ induced superior cumulative yields and consistent productivity across orchard ages. In contrast, ‘Sunki’ and ‘Caipira DAC’ performed poorly, particularly under Paranavaí’s warm-dry climate, accentuating yield instability. ‘Volkamer’ showed a marked decline in yield during the aging phase in Londrina, highlighting its limitations for long-term cultivation. Rootstock × location interactions significantly influenced tree performance, with Londrina conditions favoring vegetative growth and delayed peak yield, while Paranavaí promoted early bearing and improved yield efficiency. Juice quality and technological indices were highest for fruit from trees on ‘Carrizo’, ‘Swingle’, and ‘Trifoliate’, revealing their suitability for juice-oriented production in subtropical regions. Overall, rootstock performance varied markedly with genotype and location, emphasizing the importance of matching rootstock selection to local conditions. ‘Carrizo’ and ‘Swingle’ provided superior long-term yields, while ‘Cleopatra’ favored vegetative growth. Conversely, ‘Volkamer’, ‘Sunki’, and ‘Caipira DAC’ rootstocks showed poor long-term yield performance, particularly in Paranavaí. Rootstock choice may also affect susceptibility to pests and diseases by influencing canopy size and shoot flushing pattern. This study provides robust long-term evidence to guide rootstock selection for sustainable cultivation of ‘Valencia’ orange, optimizing tree vigor, yield stability, and fruit quality across orchard ages in subtropical citrus regions.