Effect of climate conditions on properties of hydroponic nutrient solution

The effect of climatic conditions (air temperature, light intensity, relative air humidity and CO2 air level) on dynamics of nutrient solution pH and electrical conductivity (EC) was studied in experiments. The tomatoes were grown in hydroponics greenhouse system on rockwool during year 1995-1997. In most of cases there were found only not significant correlations of pH and EC to the climatic conditions. Nutrient solution EC shown positive correlation to the light intensity in all years (r = 0.63). Partially it was found the same effect of air temperature and negative one to the relative humidity. On the other hand there was no relationship of EC and CO2 air level detected. Simultaneously computed correlation analysis shown strong positive correlation of EC and levels of N-NO3. (r = 0.90), Ca (r = 0.69), Mg (r = 0.75) and Na (r = 0.74) in nutrient solution. Relationship evaluation of pH and climatic factors results with no significant correlation. The light intensity and air temperature increasing leads to the higher water uptake by plants and with this effect is connected the nutrient levels rising in solution accompanied by the same reaction of EC. On the other hand, the pH reaction is not significantly affected during this process.