Effect of branch girdling on berry traits, chemical and sensory characteristics of 'Italia' and 'Victoria' table grapes

Girdling is an ancient agronomic technique that causes a change in the distribution of photosynthates, mineral nutrients and plant hormones. The aim of this study was to assess the effect of girdling technique on ‘Italia’ and ‘Victoria’ table grape cultivars. In this study, the carpological, physico-chemical and sensory data were evaluated. In order to assess the effect of girdling on grape volatile compounds, a headspace solid-phase microextraction was also performed. Results showed the effects of girdling on morphological, physico-chemical and sensory characteristics of table grapes with a different change of berry size and colour depending on the cultivar. The girdling treatment produced a significant decrease of sugar content and total soluble solids/titratable acidity ratio only for ‘Italia’ cultivar. The analysis of volatile compounds revealed that ‘Italia’ cultivar had three more compounds than ‘Victoria’ and that the samples taken from the girdled grapevines had fewer compounds than their ungirdled ones. The results exhibited that the girdling treatment was more effective on the ‘Italia’ cultivar. This study showed that girdling efficacy strongly depends on the cultivar. The samples from the girdled grapevines had fewer volatile compounds than the ungirdled ones. The Principal Component Analysis totally differentiated both cultivar and treatment without overlap.