光照和温度对氮饥饿及饱和营养条件下石莼(Ulva lactuca)的硝态氮吸收动力学影响

Effects of temperature and light intensity on the nitrate uptake kinetics of nitrogen starved and replete Ulva lactuca

为探讨海藻养分吸收能力并以高效养分过滤器筛选为目标,以N饥饿和N饱和的石莼为材料,研究了3种光照及温度因子及其交互作用对不同N素营养限制状态下石莼NO3-吸收动力学特征的影响。结果表明:N饱和条件下,随着光照的增强,石莼对NO3-的最大吸收速率也增加;30℃条件下,光照强度的增加虽然使得其最大吸收速率提高,但Vmax/Km在中等光强下最大;20℃最有利于石莼对NO3-的吸收。N饥饿条件下,石莼对NO3-的吸收速率显著大于非饥饿状态。在10℃和20℃条件下,呈现与N饱和条件下相似的规律,但在30℃条件下,中等光强石莼对NO3-的最大吸收速率最高。在10℃和20℃条件下,增加光强促进石莼对NO3-的吸收,但30℃条件下光强的增加并未起到促进作用。饥饿状态下的石莼的NO3-吸收速率较高,当石莼吸收NO3-饱和时,依然可以以较低的速率继续吸收环境中的NO3-。

In order to investigate the nutrient uptake ability of macroalga and to screen efficient biofilter to remedy coastal eutrophication, this paper studied the effects of three levels temperature and light intensity and their interactions on the nitrate uptake kinetics of nitrogen starved and replete Ulva lactuca. Under nitrogen repletion, the maximum nitrate uptake rate of U. lactuca increased with increasing light intensity. At 30 ℃, the maximum uptake rate increased with increasing light intensity, but the Vmax/Km value reached the highest at medium light intensity. The optimal temperature for the nitrate uptake by U. lactuca was 20 ℃, and the nitrate uptake rate was much higher under nitrogen starved condition than under nitrogen replete condition. The nitrate uptake rate of U. lactuca was similar at 10 ℃ and 20 ℃. At 30 ℃, U. lactuca had the highest maximum uptake rate at medium light intensity. The increase of light intensity enhanced the nitrate uptake at 10 ℃ and 20 ℃, but had less effect at 30 ℃. Nitrogen starved U. lactuca had a higher nitrate uptake rate than nitrogen replete U. lactuca. Even under nitrogen replete condition, U. lactuca could still take nitrate from the ambient environment.