Abstract:
Objective To study the change of physiological characteristics changes of Quercus spp. during the discoloration period and found the relationship between leaf color diversity and physiological changes. Method 4-year-old seedlings of Sect. Lobatae (Quercus texana, Q. shumardii, Q. phellos, Q. laurifolia and Q. pagoda) and Sect. Quercus (Q. lyrata, Q. michauxii and Q. fabri) were used to measure chromatic aberration parameters (L*, a*, and b*), pigment, soluble sugar, C, N and P contents during the leaf senescence stage. Result During the autumn, the leaf senescence period, the variation range of L* value was small and stable. The values of a* and b*, chlorophyll and carotenoid contents decreased whereas the anthocyanin content increased gradually. The leaf N and P contents decreased gradually in the senescing leaves, but the contents of soluble sugar in leaves increased. The a* value showed significantly positive correlations with anthocyanin and soluble sugar content, C:N ratio and C:P ratio; and negative correlations with chlorophyll, carotenoid, N and P content. In general, the leaf color of Sect. Lobatae was redder than that of Sect. Quercus, while there were significant differences among species in terms of leaf color and leaf color retention period. Due to the different magnitude of variation in each index of each species, the leaf color of Quercus spp. changed from green to yellow-red, crimson, bright red or brown in the late stage of leaf discoloration. The leaf color of Q. texana was the reddest in autumn and the red leaves occurred the longest. Conclusion Usually, the leaf color of Sect. Lobatae will change earlier than that of Sect. Quercus. In the early stages, the variation of parameters is very small. After, the leaf color of Quercus spp. is mostly affected by chlorophyll and carotenoids break down and anthocyanins will synthesize quickly. The N and P contents will gradually decrease, and the utilization rate increase significantly.