Sensitive Tolerant Parameter BRS1010 2B710 DKB 390 BRS1055   FC WD FC WD FC WD FC WD A 23,20cA 0,152bB 28,06bA 1,187bB 27,72bA 2,257aB 33,62aA 2,257aB FvFm 0,803aA 0,762bB 0,790aA 0,757bB 0,800aA 0,757bB 0,801aA 0,784aB gs 0,102cA 0,007aB 0,145bA 0,010aB 0,138bA 0,023aB 0,189aA 0,023aB E 2,107cA 0,088aB 3,886aA 0,192aB 2,347cA 0,499aB 2,979bA 0,498aB Ci 75,27aB 357,8aA 31,64aB 158,9cA 43,38aB 215,5bA 67,94aB 214,4bA A/E 11,99aA 1,645bB 7,315bA 6,508aA 11,81aA 4,592aB 11,28aA 4,599aB gm 55,17bA 0,830bB 124,0aA 22,41bB 61,62bA 83,79aA 74,65bA 86,63aA Cc 63,67aB 357,8aA 17,61bB 158,3cA 29,52bB 214,4bA 51,13aB 213,3bA PR -1,91aB 0,619aA -4,32cB 1,501aA -2,63aB 1,122aA -3,38bB 1,122aA Vpmax 38,26cA 12,54aB 43,50bA 14,01aB 42,60bA 14,94aB 48,81aA 14,94aB Vcmax 64,84cA 50,66bB 67,80bA 51,36bB 67,60bA 52,03aB 71,10aA 52,03aB Jmax 231,8cA 71,29aB 267,7bA 76,40aB 260,0bA 81,56aB 312,5aA 81,57aB ATP 1,280aA 0,882aB 1,078bA 0,844aA 1,322aA 0,963aB 1,436aA 0,963aB NADP 3,970cA 3,637cB 4,035bA 3,656bB 4,033bA 3,674aB 4,088aA 3,674aB H+ 3,842aA 2,647aB 3,233bA 2,531aB 3,965aA 2,889aB 4,308aA 2,888aB

Abreviatures: photosynthetic rate (A), stomatal conductance to water vapour (gs), maximum efficiency of photosystem II (FvFm), transpiration rate (E), internal CO2 concentration (Ci), relation of water use efficiency (A/E), mesophyll conductance (gm), chloroplastidic CO2 concentration (Cc), photorespiration rate (PR), maximum rate of carboxylation of phospoenolpyruvate (Vpmax), maximum rate of carboxylation of Rubisco (Vcmax), maximum rate of carboxylation limited by electron transport (Jmax). Means followed by the same letter are not statistically different from each other. Lowercase letters denote comparisons between genotypes within the same water level soil, and uppercase letters denote comparisons between the water levels in the soil within the same genotype. Means were compared by Scott-Knott test at 5 % probability.

Table 1: Leaf gas exchange obtained in situ and derived from A-Cc curves in four maize genotypes with contrasting characteristics for drought tolerance (BRS1010 and 2B710 - sensitive; DKB390 and BRS1055 - tolerant) grown under different water contents in the soil (field capacity - FC, and water deficit - WD) (n=6).