Enhancing Soil Physical Properties and Grapevine Performance Through Polyvinyl Alcohol (PVA) Application Rates

The aim of this study was to determine the effects of different application rates of polyvinyl alcohol (PVA), a synthetic organic polymer with soil-conditioning properties, on soil physical properties and the vegetative growth parameters of Karaerik and Narince grapevine cultivars. The experiment was conducted under greenhouse conditions using a total of 60 pots, consisting of six treatment groups, two grapevine cultivars, and five replicates. The treatment groups included three reference growing environments (control (D0), sand, sand + soil) and three PVA application rates based on weight (D1: 0.05%, D2: 0.10%, and D3: 0.30%). At the end of the experiment, soil aggregate stability (AS), air permeability (AP), water permeability (WP), bulk density (BD), and total porosity were determined. The evaluated plant morphological parameters included root length (RL), number of roots (NR), shoot length (SL), number of leaves (NL), fresh root weight (FRW), and dry root weight (DRW). In addition, several phenological observations of the grapevines were recorded. The results showed that PVA applications increased aggregate stability by 32% compared with the control treatment. Correspondingly, air permeability, water permeability, and porosity also increased significantly. In particular, the improvement in soil permeability and aeration capacity resulting from PVA application promoted the development of optimal rhizosphere conditions, leading to substantial improvements in plant morphological characteristics. Under the D3 PVA treatment, the average root length increased by approximately 75% in the Karaerik cultivar and 125% in the Narince cultivar. Similarly, fresh root weight increased by 34% and 142% in the Karaerik and Narince cultivars, respectively, under the D3 treatment. Comparable statistically significant improvements were observed for all other plant growth parameters. Overall, the findings demonstrated that the highest PVA application rate (0.30%) produced the most pronounced effects, with the greatest improvements observed in all measured plant growth parameters of the Narince grapevine cultivar.