光照对菹草(Potamogeton cripus)幼苗生长发育和光合荧光特性的影响
摘要
Light is a crucial factor for the growth of submerged macrophytes. Its influence on seeding growth and photosynthetic fluorescence characteristics of Potamogeton cripus were studied in this study. The seeding of Potamogeton cripus were transplanted into the waters with 5%, 1%, 0.5%, 0.1% and 0.05% sunlights respectively. The sunlight intensity was controlled by a Shading-net. The growth of Potamogeton cripus seeding were investigated, Meanwhile, some photosynthetic fluorescence characteristics were determined by a developed, submersible, pulse-amplitude modulated (PAM) fluorometer, Diving-PAM. The results were shown as followings: (1) The seeding of Potamogeton cripus had a significant change in growth by the different irradiance densities. The seeding heights, leaf numbers and fresh weights increase rate decreased significantly with the light decreasing; (2) The photochemical efficiency (Fv/Fm ratio) of seedings exhibited apparent difference by the different irradiance densities, and the Fv/Fm by 0.5%, 0.1%, 0.05% were 65%, 53% and 42% than that of CK in the 16(superscript th) day; (3) The photochemical quenching(up) of seeding exhibited apparent also difference by the different irradiance densities, and the qP by 0.5%, 0.1%, 0.05% were 68%, 67%, 53% than that of CK at the end of experiment; (4) The qN by 0.5% increased in the beginning experiment and reduced significantly in the late experiment, however, the qN by 0.1%, 0.05% were decreased significantly during the experiment, which indicating that the photochemical efficiency of PSII reduced at the low intensity and excitation energy entering PSII decreased, and the heat dissipation decreased; (5) The Electron-transport rate (ETR) of seeding exhibited apparent significantly decreased by the different irradiance densities, the ETR by 1%, 0.5%, 0.1%, 0.05% were 70%, 63%, 56%, 36% than that of CK an the end of experiment and the photoresponse capacity of seeding had a significant changes by the different irradiances