The effect of nutrient solution on yield, its quality and the reaction of photosynthetic apparatus of endive (Cichorium endivia) grown in hydroponics

The effects of nutrient solution and cultivar on the yield, biological value and the photosynthetic efficiency of endive were investigated. Plants were grown in hydroponic system on a standard nutrient solution. For part of the plants, the nutrient solution was changed seven days before harvest. Half of these plants were supplied with the standard nutrient solution + 30 mmol L^-1 NaCl, and the other half with water. The experiment was carried out in two growing periods: spring and autumn. Four cultivars of endive were examined. The fresh weight and contents of following substances in leaves were determined: dry matter, ascorbic acid, total soluble solids, chlorophyll, carotenoids, nitrates, P, K and Ca. Some physiological parameters, such as chlorophyll fluorescence, were measured in the middle of leaf, for 3 plants 
treatment^-1. The biological value of endive was affected by nutrient solution and cultivar. The short term of low salt stress resulted in the increase in dry matter content and total soluble solids content and decrease in the fresh weight. The application of H₂O significantly reduced nitrates and chlorophyll content in plants and decreased the yield of endive. A positive correlation between SPAD index and nitrate concentration in endive leaves was found. The nutrient solutions used did not significantly reduce the performance of photosynthetic apparatus of endive plants.