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Effect of nitrogen supply on chlorophyll (Chl) concentration and Chl/N in the sixth leaf of maize. High nitrogen: 4 mM Ca(NO3)2; Low nitrogen: 40 µM Ca(NO3)2. Bars denote the SE of the mean. ns: not significant (p > 0.05); *, ** and ***: significant at p < 0.05, 0.01 and 0.001, respectively.
