Association of mineral imbalance with leaf chlorosis under saline irrigation in Sharad seedless grapes raised on Dog Ridge rootstock

Abstract

Under saline irrigation, development of leaf chlorosis/discoloration beginning from the upper leaves has been found to cause severe reduction in productivity and life span of the Sharad Seedless grape (Vitis vinifera L.) and its mutants grafted on Dog Ridge rootstock. In the present study, mineral accumulation in vine tissues over the years under saline irrigation and association of mineral imbalance with chlorosis/necrosis was investigated during the two pruning seasons in Sharad Seedless vines grafted on Dog Ridge rootstock. The contents of nitrogen, phosphorus, potassium, calcium and magnesium were significantly lower and sodium and chloride contents were found significantly higher in upper leaf lamina of symptomatic vines. Lamina N, P, K and Ca and Mg contents were positively correlated, whereas sodium and chloride contents were negatively correlated with chlorophyll content. Significant negative correlation was observed between chloride and phosphorus and nitrogen concentration in leaf tissues. Principal component analysis revealed a negative interaction between N, P, K and Na and Cl- content in leaf tissues. Principal components (PCs) explained 91.7% of total variation in leaf lamina and were designated as PC1 (N+P+K-Na-Cl) and PC2 (N+P+K+Ca+Mg). Symptomatic vines accumulated higher sodium (>5.0 g-1/kg) than potassium content in the leaf tissues and mean potassium content in symptomatic leaf lamina was less than 5.0 g-1/kg. Increased accumulation of Na+ and Cl- in the chlorotic leaf tissues revealed that ability of Dog Ridge rootstock to exclude these salts diminished over time and long term studies are needed for identifying salt tolerant rootstocks.