7种优良观赏草光合生理日变化及光响应特征研究

采用便携式LI-6400光合测定仪,选择晴朗天气对观赏草劲芒、柳枝稷、花叶虉草、歌舞芒、矮蒲苇、遍生芒、晨光芒的叶片细胞间CO₂浓度(Ci)、气孔导度(Cond)、气孔限制值、净光合速率(Pn)、瞬时光合有效辐射(PAR)和蒸腾速率(Tr)等有关参数进行测定,并计算各材料的光合饱和点(LSP)和光合补偿点(LCP),研究材料光合日变化及其耐荫性,测定结果表明,7种观赏草中,柳枝稷的光补偿点、净光合速率和水分利用率(WUE)最高,抗旱耐荫。晨光芒和花叶虉草均有较高气孔导度,两者在净光合速率和蒸腾速率方面,晨光芒最高,花叶虉草最低,花叶虉草WUE最低,抗旱性差,在潮湿或水环境中表现好,为具有较强耐荫能力C₃型植物,出现“光合午休”现象,主要由气孔导度下降引起。根据测定的数据及田间不同相对光强下材料的生长情况综合评估,7份材料的耐荫程度由强到弱依次是矮蒲苇、花叶虉草、歌舞芒、遍生芒、劲芒、柳枝稷、晨光芒。

Diurnal change of photosynthetic characteristics and response to light intensity of seven ornamental grasses

The diurnal variations of photosynthetic rate (Pn), stomatal conductance (Cond), transpiration rate (Tr), intercellular CO₂ concentration (Ci), water using efficiency (WUE), solar radiation (PAR) of Miscanthus sinensis ‘Strictus’, Panicum virgatum ‘Rehbraun’, Phalaris arundinacea ‘Picta’, M. sinensis ‘Cabaret’, Cortaderia selloana ‘Pumila’, M. sinensis ‘Cosmopolitan’ and M. sinensis ‘Morning light’ were determined by Li-6400 portable photosynthetic system, and the light saturation point (LSP) and the light compensation point (LCP) were calculated at the same time. Among the 7 ornamental grasses, the LSP,Pn and WUE of P. virgatum ‘Rehbraun’ were the highest. Both M. sinensis ‘Morning light’ and P. arundinacea ‘Picta’ have higher Cond,the Pn and Tr of M. sinensis ‘Morning light’ were the higher and P. arundinacea ‘Picta’ was the lower. WUE of P. arundinacea ‘Picta’ was lowest with low dry tolerance and good performance at wet site which was a shade tolerance plant of C₃ plant characters with appearing noon-rest phenomenon dued to the decrease of Cond. Shade tolerance from strong to weak were ranked as follows: C. selloana ‘Pumila’＞P. arundinacea ‘Picta’＞M. sinensis ‘Cabaret’＞M. sinensis ‘Cosmopolitan’＞ M. sinensis ‘Strictus’＞P. virgatum ‘Rehbraun’＞M. sinensis ‘Morning light’.