Effects of sediment adding ammonium on root morphology and nutrition absorption of Myriophyllum spicatum
外源NH+4对穗花狐尾藻根系形态和养分吸收的影响

The root morphology, nutrition accumulation and dry biomass distribution of Myriophyllum spicatum from different treatment with ammonium chloride (SN1, SN2 and CK) adding were investigated using sediment\|water\|submerged macrophytes system in the greenhouse in static experiment condition. The results indicated that the taproot diameter (0.432-0.518 mm), taproot/lateral root ratio (1.50-4.39) of Myriophyllum spicatum increased with the increasing of ammonium contents in the sediment. Taproot total length per plant (31.64-171.67 cm ) was shorten significantly in high ammonium condition. Taproot numbers per plant in SN2 (8.17 piece) were lower than in SN1 (14.67 piece) and CK (14.33 piece) remarkably, while no significant difference between SN1 and CK. The total nitrogen contents of plant in the treatments (SN1 55.98 and SN2 55.19 mg/g) were significantly higher than that of CK (42.89 mg/g), while the total phosphorus contents of plant in the treatments (SN1 1.63 and SN2 1.53 mg/g) were significantly lower than that of CK (3.71 mg/g). The total plant dry biomass (168.17-405.81 mg/plant) and total plant phosphorus (0.25-1.51 mg/plant) increased with the increasing of sediment ammonium contents, while the rank order of the total plant nitrogen (9.12-21.08 mg/plant) was SN1>CK>SN2. The allocation ratios of total plant nitrogen and total plant phosphorus in leaf decreased, but those in root and stem increased significantly with the increasing of sediment ammonium contents.