IMPACT OF THE SOURCE SINK RATIO ON VEGETATIVE GROWTH, YIELD AND RESERVES ACCUMULATION ON A MINIMAL PRUNING VINEYARD IMPACTO DE LA RELACIÓN FUENTE DESTINO SOBRE EL CRECIMIENTO VEGETATIVO, RENDIMIENTO Y ACUMULACIÓN DE RESERVAS EN UN VIÑEDO CONDUCIDO EN PODA MÍNIMA

PACHECO, Daniela1*; PEREZ PEÑA, Jorge2; PRIETO, Jorge A.2. 1 INTA EEA San Juan, Calle 11 y Vidart, Villa Aberastain, Pocito (5427) San Juan. 2 INTA EEA Mendoza, San Martín 3853, Luján de Cuyo, Mendoza, Argentina *Corresponding author: pacheco.daniela@inta.gob.ar

Abstract: Vines under minimal pruning reach a balance between vegetative growth and yield. However, berry sugar accumulation may be delayed due to excessive fruit production and this may affect reserves restoration. In this study, we evaluated the influence of the leaf to fruit ratio (LFR) on vegetative growth, yield and reserves accumulation during two seasons on a Cabernet Sauvignon vineyard located in San Juan, Argentina. Vines were minimally pruned since 2006. Treatments imposed were based on the % of cluster thinning: control (C) 0%, T1 50%, and T2 75%. The LFR (m2 kg-1) increased with thinning intensity. The T2 presented the highest LFR values, 1.46 m2 kg-1 in 2012 and 2.11 m2 kg-1 in 2013. Shoot number, shoot length and canopy leaf area were not affected by cluster thinning. Thinning treatments accelerated maturity in both seasons compared to control. As expected, yield per vine was significantly lower in thinned plants than that of control. Thinning treatments did not affect starch nor total nitrogen content in trunk and roots after two years of cluster thinning. Our results suggest that it is not necessary to control crop load in vineyards in San Juan under minimal pruning. Even if cluster thinning accelerated maturity, the control achieved commercial maturity and the trunk and root reserves were not affected after two years of treatment.

Keywords: leaf to fruit ratio, crop load, cluster thinning, starch, total nitrogen
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