水体悬浮泥沙对黑藻生长和叶绿素荧光特性的影响

利用粒径小于100 μm的泥沙调制水体浊度分别维持在30、60和90 NTU，将黑藻幼苗种植于上述水体中，定期测定植株的分枝长、分枝数和鲜质量，利用水下饱和脉冲荧光仪（DIVING-PAM）测定叶片在光化光下的荧光参数.结果表明：随着泥沙含量的增加，植株分枝数受到明显抑制，生物量逐渐降低，而分枝长则呈显著增加趋势；随着试验时间的延长，浑浊水体中光化学最大量子产量（F_v/F_m）值呈明显〖JP2〗降低趋势，但显著高于对照.在17 μmol·m^-2·s^-1光化光照射下，与第30天相比，第60天时30、60和90 NTU组植株叶片的有效荧光产量（△F_v′/F_m ′）分别增加了48.9%、36.8%和17.2%（P<0.01），相对光合电子传递速率（rETR）分别增加了56.7%、42.2%和21.4%（P<0.01）；而在104 μmol·m^-2·s^-1光化光照射下，第60天时植株的△F_v′/F_m′、光化学淬灭系数（q_P）和rETR显著降低，且热耗散能力（q_N）也显著降低，表明黑藻植株适应低光环境, 且在高光强条件下黑藻叶片易受到光伤害.可引种黑藻幼苗于混浊的浅水水体中.

Effects of suspended silts in waters on the growth and chlorophyll fluorescence characteristics of Hydrilla verticillata

Silt particles smaller than 100 μm in diameter were used to make the waters with a turbidity of 30 NTU,60 NTU,and 90 NTU.Hydrilla verticillata seedlings were planted in the turbid waters,and their branch length,branch number,and fresh mass were measured at definite periods of time.In the meanwhile,the leaf chlorophyll fluorescence parameters were determined in situ by a submersible pulse-amplitude modulated(PAM)fluorometer(Walz GmbH,Effeltrich,Germany).With the increase of water turbidity,the branch number of the seedlings decreased remarkably,biomass also decreased,but branch length increased significantly.In turbid waters,the F_v/F_m value decreased with time,but was still higher than that in the control waters.Under the actinic light of 17 μmol·m~(-2)·s~(-1) PPFD,the effective quantum yield(ΔF_v'/F_m')of seedling leaves on the 60th day in the waters with turbidity of 30 NTU,60 NTU,and 90 NTU increased by48.9%,36.8%,and 17.2%(P＜0.01),and the relative electron transport rate(rETR)increased by 56.7%,42.2%,and 21.4%(P＜0.01),respectively,compared with those on the30th day.However,under the actinic light of 104 μmol·m~(-2)·s~(-1) PPFD,the △F_v'/F_m',qp,and rETR on the 60th day decreased significantly,and the heat dissipation capability(q_N)also reduced evidently.All the resuhs suggested that the H.verticillata seedlings in turbid waters could adapt to low light environment,but their leaves were easy to be damaged under high light intensity.Therefore,it would be possible to introduce H.verticillata seedlings in shallow turbid waters.