Photosynthetic Activity and Growth of Four Arabica Coffee Genotypes under Water Deficit

Due to the genotype-dependent effects of water deficit (WD) on coffee physiology, climate change raises the risk of coffee yield. The aim of the study was to assess the effect of WD on physiological and growth traits in arabica coffee (Coffea arabica L.). Water status, photosynthetic response to in-tercellular concentration of CO2 (A/Ci curves) and growth parameters were evaluated in seedlings of four genotypes (Catimor ECU 02, Cavimor ECU, red Caturra and Sarchimor 4260). Most of the physiological traits evaluated differed significantly among genotypes. Between control and WD plants, there were significant differences in A/Ci parameters, showing a wide range of values for photosynthetic rate, stomatal conductance, and water use efficiency, with decreases ranging from 4 to 74%. Maximum rate of carboxylation by RuBisCO, maximum electron transport rate through photosystem II, and triose phosphate utilization rate were all strongly reduced by WD 61 % (red Caturra and Sarchimor 4260), followed by Cavimor ECU (35 %) and 24 % in Catimor ECU 02. Differences in response to WD among genotypes suggest possible genotypic differences in toler-ance. The results indicated that Catimor ECU 02 and Cavimor ECU were less sensitive to WD, while red Caturra and Sarchimor 4260 were the most susceptible.