黄土区农林复合生态系统中大豆和绿豆的光合生理特性

用Li-6400光合测定系统和FMS-2.02荧光仪测定了单作及间作农林复合系统中大豆和绿豆的光合荧光参数日变化特征,进一步解析复合系统光能竞争机理.结果表明:(1)从单作到间距核桃1 m间作模式,距核桃树越近,遮光愈多,各处理大豆、绿豆的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)表现出与光合有效辐射(PAR)基本一致的先升后降的日变化模式.(2)随着遮荫程度的提高,大豆、绿豆叶绿素含量和表观量子效率(Ф)升高,而光饱和点(LSP)和光补偿点(LCP)降低.(3)随着遮荫程度的提高,大豆、绿豆叶绿素荧光参数最大光能转换效率(Fv/Fm)、PSⅡ电子传递量子效率(ФPSⅡ)以及光化学猝灭系数(qP)均有不同程度的升高,而非光化学猝灭系数(qN)却逐渐降低.研究发现,大豆和绿豆能适应间作系统的弱光环境,在较低的光照条件下正常生长,植物的光合特性与其生境特点相符.

Photosynthetic Characteristics of Soybean and Mungbean in an Agroforestry Eco-system in the Loess Area

Using Li-6400 portable photosynthesis system and FMS-2.02 fluorescence system,we examined the photosynthetic characteristics and parameters of chlorophyll fluorescence of soybean and mungbean in an agroforestry system.It was shown that(1)The photosynthetic active radiation(PAR) was reduced significantly from full daylight at 1 m from the tree(Juglans regia L.) row and the diurnal variations of photosynthetic rate(Pn),stomata conductance(Gs) and transpiration rate(Tr) of soybean and mungbean were similar to photosynthetic active radiation,and they were lower in the agroforestry system compared to full daylight.(2)The content of total chlorophyll and apparent quantum yield(Ф) of both crops increased and light compensation point(LCP) and light saturation point(LSP) decreased with increasing degree of shade.(3)The Fv /Fm,ФPSⅡ and qP were significantly higher than those under full daylight in treatments of both crops,but qN decreased with increasing degree of shade.The results indicated that soybean and mungbean had strong adaptability to low irradiance and photosynthetic characteristics of plants correspond with their environment.