灌浆期虉草不同位叶对光照强度响应能力及光合贡献率

Photosynthetic contribution rate and response of Phalaris arundinacca leaves at the different position in filling stage to light intensity

设置10个内置光照强度,测定光照强度对灌浆期虉草(Phalaris arundinacca)1-4位叶光合参数的影响,同时分析自然光下各位叶的光合贡献率与水分消耗率差异。结果表明,虉草能利用≥50μmol·(m^2·s)^(-1)光照进行光合作用;叶片光合参数受光照强度和叶位的影响极显著(P<0.01);不同位叶的4个光合参数在500~1 700μmol·(m^2·s)^(-1)光照下均无显著差异(P>0.05),当光照强度大于1 400μmol·(m^2·s)^(-1)时则有光抑制现象。水分利用效率在光照800~1 400μmol·(m^2·s)^(-1)时最高。在自然光下,不同位叶单位叶面积的光合速率(Pn)和胞间CO_2浓度(Ci)有显著差异(P<0.05),第2、3叶单叶光合速率和贡献率大于其它位叶,且水分利用效率也较高。所以,田间管理时应注意保持第1~3叶的完整与健康,以保证虉草种子发育对营养的需要。

In the present study,Phalaris arundinaccaleaves at different position in filling stage were irradiated with ten different built-in light intensity including 0,50,100,200,500,800,1 100,1 400,1 700,2 000μmol·（m2·s）^-1.The photosynthetic parameters such as photosynthetic rate,transpiration rate,stomatal conductance,photosynthetic contribution rate and water consumption rates of leaves from first to fourth position were measured to investigate the response of the P.arundinaccaleaves at different position to light intensity and its photosynthetic contribution rate.The results showed that P.arundinacca can use more than 50mol·（m2·s）^-1 intensity light for photosynthesis.Leaf photosynthetic parameters were extremly significantly affected by light intensity and leaf position（P0.01）.The net photosynthetic rate,stomatal conductance,intercellular CO_2concentration（Ci）and transpiration rate（Tr）of P.arundinaccaleaves at different position had no significant difference with 500～1 700μmol·（m2·s）^-1 illumination,however,there was photoinhibition when the light intensity was greater than 1 400μmol·（m2·s）-1.Water use efficiency reached the highest with 800～1 400μmol·（m2·s）^-1 illumination.With natural light,the photosynthetic rate and intercellular CO_2 concentration per unit leaf area of P.arundinaccaleaves at different position had significant difference（P〈0.05）.The photosynthetic rate,contribution rate and water use efficiency of second and third leaf were higher than those of other leaves.Therefore,the more attention should be paid to maintaining the integrity and health of first to third leaf for field management in order to obtain adequate nutrition for seed development of P.arundinacca.