流动沙丘先锋植物沙米对风沙流和干旱胁迫的光合生理响应

Photosynthetic Physiological Responses of the Pioneer Plant Agriophyllum squarrosum on Mobile Dune to Wind-sand and Drought Stress

以民勤野外和盆栽沙米(Agriophyllum squarrosum)为研究对象,在自然条件下设置对照、挡风墙、浇水及浇水+挡风墙处理,在风洞内干旱和浇水环境下分别设置风速(0、6、8、10和14 m·s^(-1))和吹袭时间(0、15、30、45 min)处理,采用Li-6400便携式光合仪对沙米光合生理特征进行测定,探讨风沙流和干旱胁迫互作对沙米植株光合作用的影响。结果表明:(1)在野外自然条件下,沙米叶片P_(n)日进程在对照、设挡风墙、浇水处理均呈“双峰”曲线,而在设挡风墙+浇水处理呈“单峰”曲线,且设挡风墙处理峰值比对照增加,浇水处理的“午休”时间比对照推后;叶片G_(s)、T_(r)、WUE的日变化趋势与P_(n)基本相似,而C_(i)的日变化趋势则与P_(n)基本相反;沙米WUE日均值以设挡风墙处理最高,T_(r)日均值以浇水处理最高,P_(n)和G_(s)日均值均以设挡风墙+浇水处理最高。(2)在浇水条件下,沙米叶片的P_(n)、G_(s)在低速(6 m·s^(-1))风沙流胁迫下升高,后随着风速增大而减小,其T_(r)随风速的增大而增大,WUE则逐渐减小;在干旱条件下,沙米叶片P_(n)、G_(s)和WUE均随风速的增大而降低,其C_(i)和T_(r)则升高;在相同风速下,浇水处理叶片的P_(n)、G_(s)、T_(r)和WUE均不同程度高于干旱胁迫处理,而其C_(i)和WUE均与干旱胁迫处理接近。(3)沙米叶片的光合性能在浇水条件下遭受中速(8 m·s^(-1))风沙流吹袭45 min时显著降低,在干旱胁迫下遭受中速风沙流吹袭30 min时就显著降低。研究发现,干旱和风沙流胁迫均会抑制沙米进行光合作用,浇水和设挡风墙则可以提高沙米的光合性能;沙米的光合性能在浇水条件下受到低速风沙流胁迫的显著促进,在干旱胁迫下则随风速的增大而降低;浇水可以延长沙米光合作用对持续风沙流胁迫的耐受时间。

Minqin field and potted Agriophyllum squarrosum were used as the research objects.The control,wind retaining wall,watering and watering+wind retaining wall treatments were set under natural conditions,and the wind speed(0,6,8,10 and 14 m·s^(-1))and the blowing time(0,15,30 and 45 min)were set under the drought and watering environments in the wind tunnel,respectively.To investigate the effects of wind-sand flow and drought stress on photosynthesis of A.squarrosum,we measured the photosynthetic physiological characteristics of A.squarrosum by LI-6400 portable photosynthetic apparatus.The results showed that:(1)under the natural field condition,the P_(n)diurnal progression of control,wind-retaining wall and watering treatments showed“double peak”curves,while it showed“single peak”curve in the wind-retaining wall+watering treatment.The peak value of wind-retaining wall was higher than that of the control,and the“lunch break”time of watering treatment was later than that of the control.The diurnal trends of G_(s),T_(r)and WUE were similar to those of P_(n),while the diurnal trends of C_(i)were opposite.The daily mean value of WUE was the highest in the retaining wall treatment,the daily mean value of T_(r)was the highest in the watering treatment,and the daily mean value of P_(n)and G_(s)were the highest in the retaining wall+watering treatment.(2)Under the watering condition,P_(n)and G_(s)increased under the low speed(6 m·s^(-1))sand flow stress,then decreased with the increase of wind speed,T_(r)increased with the increase of wind speed,and WUE decreased gradually.Under drought conditions,P_(n),G_(s)and WUE decreased with the increase of wind speed,while C_(i)and T_(r)increased.At the same wind speed,P_(n),G_(s),T_(r)and WUE of the watering treatment were higher than those of the drought stress treatment,while C_(i)and WUE of the watering treatment were same to those of the drought stress treatment.(3)The photosynthetic performance of A.squarrosum was significantly decreased when it was blown by medium speed(8 m·s^(-1))sand flow for 45 min under watering condition,and significantly decreased when it was blown by medium speed sand flow for 30 min under drought stress.The results showed that drought and wind-sand flow stress could inhibit the photosynthetic performance of A.squarrosum,while watering and retaining wall could improve the photosynthetic performance.The photosynthetic performance of A.squarrosum was significantly enhanced by low-speed aeolian sand flow stress under watering condition,but decreased with the increase of wind speed under drought stress.Watering could prolong the tolerance time of photosynthesis to persistent wind sand flow stress.