Change of ion content in Phyllostachys vivax and Ph. glauca and its relationships with growth and photosynthesis in coastal regions

Abstract

The changes of Na+, K+, Ca2+, Mg2+contents of 10 year-old Phyllostachys vivax and Ph. glauca and the relationships with the growth and photosynthesis were investigated in the shelter belt of coastal beach with three salt levels, i.e., 0.1% of mild salinity zone, 0.2% of moderate salinity zone, and 0.4% of severe salinity zone. Compared with the mild salinity zone, bamboo density and diameter of Ph. vivax growing in the severe salinity zone decreased by 30.4% and 28.8%, and such reductions were 44.1% and 31.2% for Ph. glauca, respectively. Salinity decreased the biomass of the two species, and the decrease of biomass in shoots was greater than that in underground organs. Compared with the mild salinity zone, the net photosynthetic rate (Pn) and the maximum PS2 photochemical efficiency (Fv/Fm) of Ph. vivax and Ph. glauca decreased by 57.6% and 67.7%, and 6.1% and 7.4% in the severe salinity zone, respectively. Ph. vivax had stronger salt-tolerance than Ph. glauca in saline environment. Na+ contents in roots, rhizome, stems, and leaves were significantly elevated in Ph. vivax and Ph. glauca with increasing soil salinity, however, the contents of K+, Ca2+ and Mg2+ were reduced. Na+ was markedly accumulated in roots, and K+ was generally enriched in shoots. Salinity led to an evident decline of Ca2+ in Ph. vivax roots and Mg2+ in Ph. glauca leaves. The biomass, Pn and Fv/Fm of the two species were usually negatively correlated to Na+ content, and positively correlated to K+ and Ca2+ contents.