Soil salinization affects growth, yield and mineral composition of cauliflower and broccoli

In coastal regions of Mediterranean areas, summer crops are often irrigated with saline water. As a consequence, salts may accumulate in the root zone, damaging the following winter crops if the rainfall is insufficient to leach them. In 1994 and 1996 we investigated the effect of residual salts from the previous summer irrigations on plant growth, yield and mineral composition of cauliflower and broccoli, two non-irrigated winter crops. The salt treatments for the irrigated summer crops were four concentrations of commercial sea salt, corresponding to ECw of 2.3 (S1), 4.4 (S2), 8.5 (S3) and 15.7 dS m(-1) (S4), plus a non-salinized control (NSC 0.5 dS m(-1)). An increase of the electrical conductivity of the saturated-soil extract (ECe) from 2.0 dS m(-1) (NSC) to 6.0 dS m(-1) (S4) caused a decrease in the marketable yield from 26.9 to 9.6 t ha(-1) and from 15.8 to 4.9 t ha(-1) in cauliflower and broccoli, respectively. A 55 and 57% salt induced leaf area reduction was observed in cauliflower and broccoli, respectively. Leaf dry matter concentration and specific leaf weight were positively correlated with ECe. In contrast, head weight and diameter were negatively correlated with ECe. Based on the Maas and Hoffman bi-linear model we ranked cauliflower and broccoli as moderately tolerant crops. The ECe thresholds were 1.52 and 1.28 dS m(-1) and the relative yield reductions per unit increase in ECe above the threshold were 14.4 and 15.8% for cauliflower and broccoli, respectively. Assessment of the relative yield as a function of soil pH revealed an 80 and 119% yield reduction per pH unit increase above a 7.2 and 7.12 threshold for cauliflower and broccoli, respectively. Head concentration of Na, Cl, S and Fe increased with soil ECe whereas N, P and K decreased. Overall, residual soil salinity and salt-induced permanent modifications of the soil physical-chemical properties affected both growth and yield of non-irrigated cauliflower and broccoli crops. (c) 2004 Elsevier B.V. All rights reserved.