FIGURE 5 Total phenol content of A. trifoliata in different habitats
3.3  | Effects of rocky desertification on enzyme activities of phenylpropanoid pathway in A. trifoliata
PAL, 4CL and C4H are the three most important enzymes in the phenylpropanoid pathway, and their activities affect the secondary metabolites of the basic phenylpropanoid pathway (Singh et al., 2009). It can be seen from Figure 6 that in the Guanling base, the PAL activity of roots and stems in the rocky desertification habitat first increased and then decreased compared with the normal habitat, while the leaves showed a gradually increasing trend. The difference of roots in September was the biggest, increased by 1.35 times; The difference of stems was the biggest in September, which increased by 6.28 times; The difference of leaves in October was the biggest, increased by 1.28 times. In Huaxi base, the PAL activity of roots in rocky desertification habitat increased first and then decreased compared with that in normal habitat, while that in stems decreased and that in leaves increased. The difference of roots was the biggest in October, increased by 1.20 times; The difference of stems was the biggest in August, which decreased by 0.89 times; The difference of leaves in September and October was the biggest, increased by 1.29 times and 1.33 times respectively. In conclusion, the PAL activity in roots and leaves of A. trifoliatacould be increased in rocky desertification habitat.