Combined effects of elevated [CO2] and high temperature on leaf mineral balance in Coffea spp. plants

Modelling studies predicted that climate change will have strong impacts on the coffee crop, although no information on the effective impact of elevated CO2 on this plant exists. Here, we aim at providing a first glimpse on the effect of the combined impact of enhanced [CO2] and high temperature on the leaf mineral content and balance on this important tropical crop. Potted plants from two genotypes of Coffea arabica (cv. Icatu and IPR 108) and one from C. canephora (cv. Conilon Clone 153) were grown under 380 or 700 mu L CO2 L-1 air, for 1 year, after which were exposed to an stepwise increase in temperature from 25/20 A degrees C (day/night) up to 42/34 A degrees C, over 8 weeks. Leaf macro -aEuro parts per thousand(N, P, K, Ca, Mg, S) and micronutrients (B, Cu, Fe, Mn, Zn) concentrations were analyzed at 25/20 A degrees C (control), 31/25 A degrees C, 37/30 A degrees C and 42/34 A degrees C. At the control temperature, the 700 mu L L-1 grown plants showed a moderate dilution effect (between 7 % and 25 %) in CL 153 (for N, Mg, Ca, Fe) and Icatu (for N, K and Fe), but not in IPR 108 (except for Fe) when compared to the 380 mu L L-1 plants. For temperatures higher than control most nutrients tended to increase, frequently presenting maximal contents at 42/34 A degrees C (or 37/30 A degrees C), although the relation between [CO2] treatments did not appreciably change. Such increases offset the few dilution effects observed under high growth [CO2] at 25/20 A degrees C. No clear species responses were found considering [CO2] and temperature impacts, although IPR 108 seemed less sensitive to [CO2]. Despite the changes promoted by [CO2] and heat, the large majority of mineral ratios were kept within a range considered adequate, suggesting that this plant can maintain mineral balances in a context of climate changes and global warming.