Staniak, MariolaKsiężak, JerzyBojarszczuk, JolantaFeledyn-Szewczyk, Beata2026-01-302026-01-302018Applied Ecology and Environmental Research 17(1): 213-230ISSN: 1589 1623 eISSN: 1785 003710.15666/aeer/1701_213230https://bc.iung.pl/handle/123456789/4689https://www.aloki.hu/indvol17_1.htmWater deficit in the soil is one of the factors that limit the yield of crops, causing great damage to agricultural production. This is the result of genotypic expression as modulated by interaction with the environment. The effect of water deficit on gas exchange parameters of Festulolium hybrid and red clover grown in pure stand and in mixture were studied. Two-factor pot experiment was performed in the completely randomized block method, with four replications. Objects were evaluated at two soil moisture levels: well-watered conditions and drought stress. The studies have shown that all the measured parameters were affected by drought stress. Net photosynthetic rate, transpiration rate and stomatal conductance were significantly lower under drought stress than under well-watered conditions in all treatments. Red clover grown in a pure stand responded to stress the most, while Festulolium hybrid – the least. It was also found that the highest water use efficiency index (WUE) was observed in Festulolium which proves a more economical water management compared to red clover. The mixtures showed smaller yield losses under drought stress compared to red clover grown in pure stand, which indicates their higher suitability to be grown in areas with less rainfall.enphotosynthesis, transpiration, stomatal conductance, water-use efficiencyArticle