Relationships among root traits
Based on the Kaiser’s criterion (Kaiser 1958), data could be condensed
in two factors, and the results indicated that the two – first
eigenvalue represented 88% of all the variability (Figure 1). After
varimax rotation, high root growth correlation for the first factor was
observed among TRL, RSA, RV and RT, and they all had positive
correlations with the first factor, or with each other respectively. For
the second factor, high root growth correlation was observed among root
biomass, SRL and RTD, whereas SRL had a negative correlation with the
second factor (Figure 1). In brief, there were two response types for
assessing root growth of S. breviflora , one was related to root
biomass, and another was related to root morphological traits.