苏北盐沼芦苇替代互花米草的化感效应初步研究

以芦苇(Phragmites australis)凋落物为实验材料,采用溶液浸提法和厌氧腐解法,获得水提物和腐解产物两种母液,并将每种母液分别稀释为50%母液和25%母液.试验中以母液、50%母液和25%母液这3种浓度的溶液分别处理米草(Spartina alterniflora)种子和刚刚萌发的米草幼苗以及米草滩涂中特有的被孢霉属米草益生菌(Mortierella sp.),考察其对米草种子的萌发、幼苗生长以及菌落生长的影响.在种子萌发试验中,对照组萌发率为36%,种子发芽速度指数为1 667;而水提物处理组依照浓度从高到低的次序萌发率依次为23%、24%和34%,发芽速度指数依次为1 184、1 037和1 328.芦苇水提物能够降低米草种子萌发率并减缓其萌发速度.并且高浓度的溶液与低浓度溶液相比,抑制效果更明显.腐解产物处理组萌发率依次为29%、29%和35%,发芽速度指数为884、980和1 272,米草种子的萌发率和发芽速度都受到了明显的抑制,尤其是在高浓度的处理液中.并且,这种抑制效应随着处理液浓度的降低而逐渐减弱.在幼苗生长试验中,以化感作用效应RI(response index)为指标考察了水提物和腐解产物对于米草幼苗生长的影响.水提物处理组中,处理液对米草幼苗和幼根的生长均无显著影响.腐解产物处理组对米草幼苗的生长没有显著影响,对于幼根长度的化感作用效应为-0.84,-0.30和0.27,说明腐解产物溶液对于米草幼根的生长有着明显的高抑低促的现象.在对米草益生菌的实验中,对照组菌落直径为3.75 cm,水提物处理组按浓度从大到小菌落直径分别为3.05 cm、2.90 cm和3.31 cm,腐解产物处理组菌落直径依次为3.57 cm、3.25 cm和3.20 cm.处理组和对照组之间有显著差异,说明水提物和腐解产物对米草益生菌的生长有显著的抑制效果,但在所选的浓度区间之内随浓度变化没有显著差异.

Allelopathy in the Progress of Phragmites Substituting Spartina from Salt Marsh in Northern Jiangsu

The litter of Phragmites australis was used to study the allelopathy in our experiments.After the water extraction and decomposing products being diluted to 50% and 25% of the mother liquors,respectively,these two solutions and the mother liquors with three concentrations were used to treat seeds and seedlings of Spartina alterniflora as well as a kind of endemic beneficial fungi of Spartina alterniflora that belonged to the genus of Mortierella to observe the effects.In the germination experiment,the germination ratio of the control was 36% and the index of seed-sprouting speed IS was 1 667,while the germination ratios for treatments of water extraction from high to low concentrations to low were 23%,24% and 34% and the values of IS were 1 184,1 037 and 1 328,respectively.Thus the water extraction of Phragmites australis can decrease the germination ratio and seed-sprouting speed of Spartina alterniflora.The higher the concentration was,the better it performed.The germination ratios of treatments of decomposing products were 29%,29%,35% and the values of IS were 884,980 and 1 272,respectively.They were significantly decreased,especially by the high concentration of the solution.In the experiment of seedling growth,RI(response index)was used to express the effects of water extraction and decomposing products on the growth of Spartina alterniflora seedling.The water extraction had no effect on growth of seedling and young shoots,neither did the decomposing products.However,the values of RI to the shoots from high concentration to low were-0.84,-0.30 and 0.27,suggesting that high concentration of decomposing products restrained the growth of young shoots of Spartina alterniflora but low concentration promoted it.In the experiment of fungi growth,the diameter of the colony of control was 3.75 cm,while those treated by water extraction were 3.05 cm,2.90 cm,3.31 cm and those treated by decomposing products were 3.57 cm,3.25 cm,3.20 cm.Significant difference between the control and treatments indicated that water extraction and decomposing products can restrain the growth of colony but there was no significant difference among various concentrations.