Influence of manganese on growth, physiological effects of chestnut seedlings

A shortterm cultivation simulation experiment was carried out to investigate the influence of manganese on growth, physiological effects of chestnut seedlings. The responses of photosynthetic characteristics, chlorophyll content, seedling height, diameter, root, biomass and contents of mineral elements in leaves to different Mn2+ concentrations (0, 0.905, 1.810, 2.715 and 3.620 mg/L) were studied. The results show that in the range of Mn2+ 0-2.715 mg/L, the Pn, Gs, Tr, chlorophyll content, seedling height, diameter, root weight and biomass of chestnut seedlings are enhanced significantly (P0.05) with the increase of the concentration, however when Mn2+ concentration is over 2.715 mg/L, the above indexes are decreased. That is to say, 1.810 and 2.715 mg/L are the most effective treatments with no significant difference between the two treatments (P0.05). Compared with CK, the Mn2+ manganese absorptions are increased under different Mn2+ concentrations, while the absorptions of calcium, iron and copper are restrained. With the increase of the Mn2+ concentration, the contents of phosphorus and boron are increased first and then decreased, while the potassium contents are in the opposite variation tendency. The results of correlation analysis show that there are significant negative correlations (P0.05) between the contents of manganese, and the contents of calcium, iron and copper. A positive correlation between manganese and boron contents, and negative correlations between manganese and phosphorus, potassium contents are also found in the experiment, but not significant (P0.05). In conclusion, the treatments of 1.810 and 2.715 Mn2+ mg/L could promote photosynthesis and growth, and it is unfavorable for the plant growth and for the balanced absorptions of mineral elements when the Mn2+ concentration is higher than 2.715 mg/L.