不同温度下甜高粱叶片光合作用的气孔限制和非气孔限制特征分析

Stomatal and non-stomatal limitations to photosynthesis in Sorghum bicolor at diferent temperatures

甜高粱(Sorghum bicolor)是一种重要的经济作物,在我国牧草中占据很大比重。为探索温度对甜高粱叶片光合作用气孔限制方面的影响,本文利用LI-6800光合仪研究了不同温度下甜高粱叶片的净光合速率(P_(n))、胞间CO_(2)浓度(C_(i))、气孔导度(G_(s))和气孔限制值(L_(s))对光强的响应规律,通过分析它们的变化关系解析了不同温度下甜高粱叶片光合的气孔限制和非气孔限制特征。结果表明,甜高粱早熟品种‘KFJT-1’的P_(nmax)随温度升高不断增大,对高温表现出较强的耐受能力。但在较高光强下(>1300μmol·m^(-2)·s^(-1))叶片发生了一定程度的光抑制,并随着温度升高发生光抑制的光强不断增大,这可能与高温下甜高粱叶片G_(s)的增大有关。甜高粱叶片的(C_(i))和L_(s)对光强的响应呈现出明显的负向同步变化,以(C_(i))和L_(s)变化的方向为依据可以准确地判断甜高粱光合速率下降的气孔和非气孔限制。在25和30°C时,较高光强下限制甜高粱叶片光合作用的因素主要为非气孔限制;而35°C时,较高光强下的甜高粱叶片受到了明显的气孔限制。

Sweet sorghum(Sorghum bicolor)is an important cash crop,which occupies a large proportion of the forage grass in our country.The project aims to evaluate the effect of temperature on the characteristics of stomatal and non-stomatal limitations of leaf photosynthesis in sweet sorghum‘KFJT-1’that is an early maturity mutant.The changes of net photosynthetic rate(P_(n)),stomatal conductance(G_(s)),intercellular CO_(2)concentration(C_(i))and stomatal limit value(L_(s))in leaves of sweet sorghum under different temperatures were measured and analyzed using a LI-6800 portable photosynthesis analyzer.The results indicate‘KFJT-1’showed a strong tolerance to high temperature(35°C),its P_(nmax) increased while temperature rising.However,the increase of light intensity above 1300μmol·m^(-2)·s^(-1)triggered a slight photoinhibition in leaves of sweet sorghum,and the saturated light intensity(I_(sat))where photoinhibition occurred increased with the increase of leaf temperature,which may be attributed to the increase of G_(s)under high temperature.Synchronous changes in opposite directions for leaf(C_(i))and L_(s)were observed.Based on these results,we found that the main limiting factor for leaf photosynthesis of sweet sorghum under higher light intensities was the non-stomatal limitation at 25 and 30°C;while at 35°C,it was the stomatal limitation.