Abstract:  In order to investigate the relationship between the nutrient contents in needle of Pinus massoniana and its resistance against the pine armoured scale, Hemiberlesia pitysophila, contents of some nutrients were measured, including soluble sugar, total sugar, soluble protein, total N, free amino acids, crude fat and total sugar/total N in the needles of ten pine families both damaged and undamaged by H. pitysophila. Discriminant analysis was applied to analyze the relationship between seven indicators and the resistance of P. massoniana against H. pitysophila. Contents of soluble protein (X₃), total N (X₄) and total free amino acids (X₇) in the pines damaged or undamaged showed significant differences, suggesting they can be used for the indicators to distinguish the resistant group from the susceptible group. The three indicators increased with the decrease of tree resistance. The contents of the three nutrients in damaged pine were all significantly lower than those in undamaged pine. The total N (X₄) was significantly variable in discrimination of the resistance levels. The variation of soluble protein (X₃), total N (X₄) and total free amino acids (X₇) in the damaged pines all decreased while the resistance decreased. It is concluded that soluble protein (X₃), total N (X₄) and total free amino acids (X₇) might be the most important resistance indices. These indices and their variation have significantly negative and positive correlation with the tree’s resistance against H. pitysophila, respectively. The all seven indicators and their variation changed while the pine needles were injured, showing a correlation between the resistance and construction of the variable of effective discriminant functions. Compared with multiple comparisons and analysis of variance, the discriminant analysis seems more comprehensive and scientific for multi-target, multi-object and multi-group analysis.

Key words: Pinus massoniana, Hemiberlesia pitysophila, insect resistance, nutrient, discriminant analysis