Abstract:

Comparing the cold resistance of different introduced mixed-growth bamboo species, the excellent bamboo species were selected for the promotion of southern bamboo introduction to north and afforestation. Using the two-year old transplanted mother bamboos of 11 bamboo species, namely Pleioblastus fortunei, Pl. viridistriatus, Pl. pygmaeus, Shibataea kumasaca, Indocalamus latifolius, S. hispida, I. decorus, I. latifolius f. flavistriatus, Pseudosasa japonica var. tsutsumiana, Ps. japonica, Chimonobambusa sichuanensis, as materials, this study explored their morphological and physiological responses to natural low temperatures for 6 consecutive years after introduction. The cold resistance of different bamboo species was comprehensively evaluated through principal component analysis combined with the membership function method. Under natural low temperature stress, the external morphology of the 11 bamboo species showed significant adaptive changes, mainly manifested as typical cold damage symptoms such as leaf yellowing, death of newly sprouted bamboo and mother bamboo. Photosynthetic physiological indicators showed that natural low temperature significantly inhibited the actual photochemical efficiency Y(Ⅱ) of PSⅡ, the maximum electron transport rate (ETR), the maximum photochemical efficiency of PSⅡ (Fv/Fm), and the effective photochemical efficiency (Fv/Fo) of the 11 bamboo species. With the extension of the introduction time, the variation ranges of the photosynthetic parameters of each bamboo species showed significant differences, reflecting obvious differences in the tolerance levels of different bamboo species to natural low temperature stress. The results of principal component analysis showed that after dimensionality reduction of 7 single indicators, 4 principal components could be extracted, with a cumulative contribution rate of 93.0%. By calculating the comprehensive evaluation value D of cold resistance, the final ranking of the cold resistance abilities of the 11 bamboo species was obtained as follows: I. decorus> I. latifolius f. flavistriatus> Ps. japonica var. tsutsumiana> S. kumasaca> I. latifolius> Pl. viridistriatus> Pl. pygmaeus> C. sichuanensis> S. hispida> Ps. japonica> Pl. fortunei.

Key words: amphipodial bamboo species, cold resistance, principal component analysis, membership function method, comprehensive evaluation