外源NH4^＋对穗花狐尾藻根系形态和养分吸收的影响

Effects of sediment adding ammonium on root morphology and nutrition absorption of Myriophyllum spicatum

在温室内进行静态实验,以原沉积物(CK)和分别添加0.24%和0.48%氯化铵(SN1和SN2)的沉积物作为底质培养沉水植物,探讨了高NH4+环境中穗花狐尾藻的根系形态特征及营养物质积累与干物质分配策略。结果表明,穗花狐尾藻主根直径(0.432-0.518mm)与主根/侧根比率(1.50-4.39)均随着沉积物NH4+含量升高呈现增大趋势,但单株主根总长(31.64-171.67cm)则在高NH4+环境中显著变短;其中,SN2处理中穗花狐尾藻主根数量(8.17条/株)显著低于SN1(14.67条/株)和CK(14.33条/株)处理,而SN1与CK处理之间差异不显著。SN1和SN2处理中穗花狐尾藻植株全氮含量(55.98和55.19mg/g)均显著高于CK(42.89mg/g)处理,而SN1和SN2处理中穗花狐尾藻植株全磷含量(1.63和1.53mg/g)则比CK处理中(3.71mg/g)显著降低。穗花狐尾藻植株干物质积累量(168.17-405.81mg/株)和全磷积累量(0.25-1.51mg/株)均随沉积物NH4+含量升高而显著下降,但植株全氮积累量(9.12-21.08mg/株)则表现为:SN1>CK>SN2。全氮和全磷在叶片中的分配率都随着沉积物NH+含量升高而显著降低,而在根系和茎秆中分配率则显著增加。

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.