Study of temporal stability of within-field variability for total soluble solids in four irrigated grapevines growing under semi-arid conditions
Résumé
The aim of this work is to study the intra and inter-annual Temporal Stability of the Within-Field Variability (TSWFV) of Total Soluble Solids (TSS) as an estimate of grapes quality. The experiment was carried out on four fields (one cv. each) of the cvs Cabernet Sauvignon, Chardonnay, Sauvignon Blanc and Carménère, all of them located in the Maule Valley, Chile, under irrigated conditions. A regular sampling grid was designed within each vine fields. On each sites TSS was measured at different dates (from veraison to harvest), using a thermo-compensated reflactometer. A Kendall test (W) was used to analyse the TSWFV between all dates measured for each cv and season. A non parametric rank coefficient of correlation (Spearman) was used to analyse the relationships between sampling dates, taking as reference the harvest. Results of the study highlight the within-field variability observed in TSS. W highlights a significant intra and inter annual TSWFV and Rank coefficients of correlation were high and significant. For PV management these results are significant and show that, under simiarid conditions, TSS maps obtained 40 days before harvest present the same spatial patterns until harvest. Early maps may be used to define relevant quality zones for differential harvest.