Die Bodenkultur - Journal for Land Management, Food and Environment


Effect of seawater and soil salinity on ion uptake, yield and quality of tomato (fruit)


In a pot experiment the influence of irrigation with artificial seawater and of soil salinity on tomato plants and fruit quality was investigated. The surn of the salt concentrations in irrigation water was 0, 30, 60 and 100 mM (seawater salinity: NaCl: MgCl2 : MgS04=20 : 1 : 1; soil salinity: Na2S04 : MgC12=4: 1 on molar basis). Dry matter production of tomato plants was significantly increased by soil salinity but not by seawater salinity. Tomato fruit production was adversely affected only by high salt concentrations. Salt stress increased the uptake of Na, Mg and chloride ions in tomato plants. Sodium reduced the uptake of potassium due to ion antagonism. Sulphate uptake in tomato plants was increased by salt application only under soil salinity Phosphate ion uptake was significantly reduced by salt stress. Chloride ions did not antagonize the uptake of nitrate in tomato plants. Absorption of calcium remained unaffected by salt stress. Iron uptake decreased significantly only under seawater salinity. Glucose, fructose, ascorbic acid and citric acid contents were signifieantly enhanced in tomato fruits by salinity; synthesis of sucrose and malic acid remained unaffected. The increases in the concentrations of sodium, chloride and monosaecharides might have contributed to osmotic adjustment in tomato plants. Salinity inereased the eontents of sugars and acids (ascorbic and citric acid) of the tomato fruits and thus improved the fruit quality. Key-words: tomato, fruit quality, osmotic adjustment, ion balance, salinity.