Effects of manganese in solution culture on the growth of five deciduous broad-leaved tree species with different successional characters from northern Japan

The effects of four manganese (Mn) concentrations (1, 10, 50, and 100 g m(- 3) = Mn-1, Mn-10, Mn-50, Mn-100) in solution culture on growth variables we re studied for seedlings of five deciduous broad-leaved trees with differen t successional characteristics and shoot development patterns in northern J apan. The five species were: Betula ermanii, Betula platyphylla var. japoni ca, and Alnus hirsuta (early-successional species with continuous leaf deve lopment), Ulmus davidiana var. japonica (mid-successional species with flus h and continuous leaf development), and Acer mono (late-successional specie s with a flush type leaf development). In plants grown in the Mn environmen t for about 45 d, relative growth rate (RGR) decreased with increasing Mn s upply. Between the 1 and 100 g(Mn) m(-3), RGR decreased by 20 % for B. erma nii and B. platyphylla, by 40 % for A. hirsuta and A. mono, and by 80 % for U. davidiana. Specific leaf area (SLA) and leaf mass ratio (LMR) of all sp ecies were little affected by high Mn supply. In U. davidiana, however, the re was a 67 % decrease in LMR in Mn-100 plants. Leaf area ratio (LAR) was h igher in early-successional species than in mid- and late-successional ones but differed little among Mn treatments within species, except for U. davi diana where LAR declined substantially with increased Mn supply. While LAR, which represents the relative size of assimilatory apparatus, was little a ffected, net photosynthetic rate (P-N) saturated with radiant energy decrea sed with increasing Mn supply in all species. Thus P-N was adversely affect ed by high accumulation of Mn in leaves, which resulted in an overall reduc tion in biomass production. However, the proportional allocation of photosy nthates to the assimilatory apparatus was not affected by different Mn toxi city in hardwood tree seedlings.