LAUSR

Abstract Increased phosphorus (P) available in soil can modify the partitioning of P forms in annual and perennial organs of grapevines throughout the growing season. This study was to evaluate the distribution and redistribution of P forms in organs of grapevines grown in soils with different contents of available P. The study was conducted in two vineyards installed in the city of Santana do Livramento, state of Rio Grande do Sul (RS), in southern Brazil. The treatments were vineyard 1 (V1) with 11.8 mg kg−1 of available P in soil and vineyard 2 (V2) with 34.6 mg kg−1. The cultivar of both vineyards is Tannat (Vitis vinifera L.) grafted on SO4 (Vitis berlandieri × Vitis riparia) rootstock. Plant density per hectare was 2525 (1.2 m × 3.2 m) on a spur pruned cordon system. The grapevines were uprooted and partitioned into roots, trunks, arms, spurs, new-year shoots, leaves and clusters (when present) at flowering (F), veraison (V), harvest (H) and dormancy (D). The organs were dried, prepared and subjected to chemical fractionation of P, to estimate fractions of total acid-soluble P (PST), acid-soluble inorganic P (PSI), acid-soluble organic P (PSO) (by difference between TSP and PSI), phospholipids P (PLIP), P associated with RNA (PRNA), P associated with DNA (PDNA) and residual P (PRES). P in grapevines of V1 and V2 accumulated mainly in the PSI fraction in leaves and clusters, which was collected at F, V and H, and in PSO fraction in roots, collected at D. Part of the root PSI was redistributed at F to the leaves and clusters in vines of V1. Vines grown in V2 accumulated more P in PSO form in roots and tended to redistribute less PSI to the leaves and clusters after F. Grapevines accumulated P in roots, both in soils with low and high available P contents, and P was subsequently redistributed and accumulated in leaves and clusters in inorganic form.