Effect of soil moisture and transpiration on mineral content in leaves and berries of Cabernet sauvignon grapevine

Leaf and berry transpiration ratio in grapevine (Vitis vinifera L.) was found to be affected by soil moisture. With the condition of diminished soil moisture, berry transpiration is higher prior to veraison compared to conditions when the water content in the substrate is higher and berry transpiration decreases with an increase of leaf transpiration. Studies were conducted in 1993 and 1994 to investigate the link between soil moisture, traspiration, and accumulation of certain mineral elements in leaves and berries on plants of the Cabernet sauvignon cultivar grafted on Kober 5 BB rootstock. Leaf and berry transpiration and mineral accumulation were evaluated by gaseous exchange measurements, soil sampling and moisture analysis, and leaf and berry sampling and analysis of mineral content. Observations were repeated at about 15-day intervals between full bloom and berry ripening. Transpiration per unit of surface area (mmol H2O m-2 s-1) was always higher in leaves than in berries. Leaf transpiration varied from 5.62 mmol H2O m-2 s-1 to 2.92 mmol H2O m-2 s-1 in 1993 in the period between the 8th and 86th day after full bloom (DAFB), and from 6.49 mmol H2O m-2 s-1 to 4.37 mmol H2O m-2 s-1 in 1994 between the 12th and 94th DAFB. Berry transpiration ranged between 3.86 mmol H2O m-2 s-1 and 1.04 mmol H2O m-2 s-1 in 1993 and between 4.34 mmol H2O m-2 s-1 and 0.5 mmol H2O m-2 s-1 in 1994. Leaf transpiration was not correlated with the mineral element content in the leaves, whereas berry transpiration was directly correlated with the nitrogen (N), calcium (Ca), potassium (K), and phosphorus (P) content in berries. Leaf mineral composition was affected only for iron (Fe) content by the variation on soil moisture, whereas the berry N, P, K, and Ca contents were positively correlated with soil water content. The leaf and berry Ca content appeared to be greater with high soil moisture, i.e., in conditions which favor intense metabolism of the whole plant.