Fig. 4

The scatter plot of 24 wheat cultivars basesed on the scores of the first two principle components. The values of shoot dry weight, root to shoot ratio, root length, electrical conductivity, chlorophyll content, hydrogen peroxide content, malondialdehyde content, soluble sugar content, starch content, total non-structural carbohydrates, carbon to nitrogen ratio, leaf total nitrogen content, palmitic acid, hexadecylenic acid, hexadecadienoic acid, hexadecatrienoic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and double bond index for the 24 cultivars were included in the principle component analysis. The wheat cultivars represented by the numbers are corresponded to those of Additional file 1. All the data are analyzed based on the ratio of N deficient to N sufficient treatments. The low N-deficiency sensitive cultivars are circled with green rectangle, the high N-deficiency sensitive cultivars are circled with red ellipse, the moderate cultivars, number 17 and 19 are shown with blue arrows