Genetic differences as estimators of osmotic adjustment and source-sink balance in grapevine hybrid elites

Abstract

This study deals with the best responses of a diverse collection of grapevine genotypes to osmotic stress associated with source-sink balance responses given by an estimator such as leaf area to fruit ratio. ‘Centennial Seedless’, a drought tolerant cultivar, was selected as control. The cultivars, ‘Victoria’ and ‘Argessis’, were chosen as a repetition from previous research dealing with pollen grain test, two years ago. Ten genotypes were hybrid elites in first and second hybrid generations. Three cultivars ‘Victoria’, ‘Centennial Seedless’, and ‘Argessis’ were grown under field conditions in containers, and in the soil under greenhouse conditions. Significant differences were found between genotypes for both responses to osmotic stress and source-sink balance. ‘Centennial Seedless’ and ‘BP9’ hybrid showed the best responses of induced osmotic adjustment; results confirmed the compensatory potassium uptake theory. ‘Victoria’ and ‘Argessis’ had almost the same average values as ‘Centennial Seedless’ osmotic estimator for induced osmotic adjustment. ‘Victoria’ and ‘HR7’ hybrid showed an increase in osmotic stress in the cell, after application of polyethylene glycol solutions without potassium cation and a lower source-sink ratio, which could be associated with higher photosynthesis rates. No correlations were identified between the mechanisms expressed by the analyzed estimators, indicating that they are activated and functional separately from each other, sometimes only compensatory.