Pepper plants (Capsicum annuum L.) were hydroponically grown under glasshouse condition to study the effects of different strength of nutrient solution on the growth, transpiration, xylem exudation rate and ionic composition of the xylem sap. They were grown for 30 days in 1/4, 1/2, 2 and 4 times of standard nutrient concentration (NOD N 8.2, NH₄-N 0.8, H₂PO₄^- 2.4, K^+ 6.0, Mg^(2+) 2.0, Ca^(2+) 3.0 and SO₄^(2+) 2.8 me/ℓ).
The expansion of leaf area was severely reduced by low concentration of nutrient solution while high concentration did not affect. Transpiration and xylem exudation rate were the highest in the standard and in double ionic strength of nutrient solution. Anion(NO₃ + H₂PO₄ + SO₄^(2+)) to canon (K^+ + Ca^(2+) + Mg^(2+)) and K^+ to Ca^(2+) ratio in xylem sap were around 1.0 in all the nutrient concentration except standard nutrient solution which was 0.85. About two times of nitrate was absorbed compared to phosphorus while potassium and calcium were absorbed at equal amount in standard nutrient solution. There was a positive correlation between calcium concentration in xylem sap and the amount of transpiration.
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