Limitations to photosynthesis inCoffea canephoraas a result of nitrogen and water availability

摘要: Summary Plants of C. canephora grown in pots under low nitrogen (LN) or high (HN) applications were submitted to either cyclic water stress daily irrigation. Water deficit led marked decreases net carbon assimilation rate (A) and, a lesser extent, stomatal conductance (gs), regardless the N treatments. In well-watered plants, A appreciably increased HN plants relative LN without significant changes gs. As whole, internal CO2 concentration predominantly reflected rather than Under irrigated conditions, A, but not gs, correlated with leaf curvilinear way. Photosynthetic nitrogen-use efficiency was considerably low, and decreased increasing concentration. Limited N, water, slightly maximum photochemical photosystem II (PSII). continuous irrigation, had smaller quantum yield electron transport (ϕPSII) through slight quenching (qp) capture excitation energy by open PSII reaction centres, increases Stern-Volmer non-photochemical quenching. water-stressed photochemistry apparent only 25 % decrease ϕPSII, due mainly variations qp. Biochemical constraints, limitations, provoked limited supply water.