Mineral Nutrition of Leafy Vegetable Crops Irrigated with Saline Drainage Water

ABSTRACT Nine leafy vegetable crops were grown in outdoor sand plots to determine the effects of salinity and the timing of salt stress on leaf-ion concentration. Vegetable species were: radicchio (Cichorium intybus L.), curly endive (C. endivia L.), pac choi (Brassica rapa L., chinensis group), tatsoi (B. rapa L., narinosa group), kale (B. oleracea, acephala group), cooking greens (B. rapa L.), mustard greens (B. juncea (L.) Czerniak), spinach (Spinacia oleracea L.), and Swiss chard (Beta vulgaris L.). All species were planted at the same time and irrigated with a complete nutrient solution. Three weeks after planting, six saline treatments were imposed on half of the plants; the remaining plants were salinized four weeks later. Saline solution compositions were prepared to simulate the high-sodium, high-sulfate drainage waters typically found in the San Joaquin Valley of California. Electrical conductivities of the irrigation waters (ECi) were 3 (control), 7, 11, 15, 19, and 23 dS.m−1. Mineral ion concentrations in leaves were significantly affected by increasing salinity, but not by the stage of growth when salinity was applied. With increasing salinity, Ca2+ and K+ decreased in the leaves of all species, whereas Na+ and total-S significantly increased. Magnesium in leaves of the composites and the crucifers also increased with salinity, but treatment had no effect on Mg2+ concentration in the chenopods. Increases in salinity caused significant increases in Cl− in leaves of the crucifers and spinach but had no influence on the Cl− relations in Swiss chard and the composites. The use of moderately saline irrigation waters for the production of these leafy vegetable crops did not adversely affect crop quality as rated by color, texture and the mineral nutrient content available to consumers.