Changes of Photosynthetic and Antioxidant Activity of Phaseolus vulgaris to Potassium

Greenhouse experiment was conducted with two cultivars of common beans and four concentrations of potassium (1, 2, 10 and 20 millimolar –mM ) were supplied to the soil pots aiming to access variations in plant antioxidant defense systems (secondary metabolites and enzymatic mechanisms), growth parameters and leaf gas-exchange measurements. The total fresh leaf mass increased in both cultivars from 1 to 10 mM of potassium and the dry matter content decreased from 1 to 20 mM. Root volume significantly increased in Uirapuru cultivar. Potassium increased chlorophyll A in both in the range of 1 to 10 Mm. Catalase activity and carotenoids increased only in Dama cultivar. Potassium increased the photosynthetic activity in cultivar-dependent manner. Cultivar ‘Dama’ showed higher intrinsic water use efficiency, NDVI index, chlorophyll contents, total leaf mass and higher catalase activity. If the selection of cultivar under those traits is aimed, ‘Dama’ cultivar is a candidate and presented a linear stomatal conductance model.