THE SIMULTANEOUS EFFECT OF HEAT STRESS AND WATER SUPPLY ON TOTAL POLYPHENOL CONTENT OF EGGPLANT

Eggplant is considered as one of the healthiest vegetables due to its nutritional values. A 2-year open field experiment was set up in 2011 and 2012 to observe the effects of heat stress and different irrigation volumes on the amount of phenolic compounds, fibre and dry matter in eggplant fruits. The optimal irrigation volume (IO) was calculated from the daily potential evapotranspiration and was compared to a treatment utilising 50% of the optimal water volume (I50). We concluded that there was no significant difference between the irrigation levels in the aspect of total polyphenol and dry matter, but there was a decrease in fibre content. Yield was increased by 19.6% with irrigation in 2011 and by 4.44% in 2012. The effect of heat stress is closely related to harvest time. In our study we proved that more heat stress resulted in more total polyphenol content in eggplant, the equation describing this relation is y=39.322+0.501x. Heat stress also stimulated dry matter and fibre content, and this influence was also significant.