Influence of shoot number on the global productivity of positioned and non-positioned training systems

Abstract

The global productivity of a vineyard is conditioned by the development of leaf area. The shoot density and the spatial distribution of leaf area influence the porosity of the canopy and the production of dry matter. The aim of this study was to determine the influence of the shoot density in the production of biomass in renewable parts and in the canopy microclimate, in both positioned and non-positioned training systems. The trial was developed during 2013 and 2014, in a Cabernet Sauvignon vineyard in Albacete (Spain). In two different training systems, one positioned -Vertical Shoot Positioned (VSP)- and another not positioned -Sprawl-, three levels of shoot density were established: 35 000, 55 000 and 70 000 shoots per hectare. At maturity the total leaf area, the external leaf area and the volume occupied by the canopy were determined, and the leaf area density was calculated. At the end of ripening, the biomass produced in renewable vegetative organs –leaves and shoots- and reproductive organs -cluster – were determined. The higher the shoot density was the greater the production of total biomass, due to increased biomass production in clusters. The individual shoot vigour offset the differences in shoot density, so no differences were observed in the production of vegetative biomass due to the shoot density. The increases of vegetative growth and biomass accumulation due to increased shoot density were higher in Sprawl, the not positioned training system, than in VSP, the positioned one. In 2013, with the increasing of the density of shoot, the amount of biomass produced by leaf area increased in both training systems. But in 2014, no significant differences were found. The increase of leaf area density caused by the increase of the shoot number was higher in VSP than Sprawl. With higher density of shoot, canopy have higher densities of leaf area and therefore less porous.