局部根区灌溉对裸燕麦光合特征曲线及叶绿素荧光特性的影响

摘要

为探讨局部根区不同灌溉方式下裸燕麦(Avena nuda L.)光合能力下降的生理机制,采用盆栽及渗水盘供水方法,比较了交替根区灌溉(APRI)、固定根区灌溉(FPRI)和常规灌溉(CTRI)下,裸燕麦旗叶相对叶绿素含量(SPAD值)、光合特征曲线及叶绿素荧光动力学特性的差异.与CTRI处理相比,局部根区灌溉(包括APRI和FPRI处理)降低了叶片SPAD值、净光合速率(Pn)和初始羧化速率(CE),但APRI处理未明显降低初始量子效率(α)、PSII最大量子效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、电子传递效率(ETR)和光化学效率(QP).在2种局部根区灌溉模式中,APRI较FPRI显著提高了叶片SPAD值(p＜0.05),而且APRI的叶片最大净光合速率(Pmax)、α、光饱和点(LSP)、光能利用率(LUE)、Ci/Ca、CE、CO2饱和点(Ci,sat)、初始荧光(Fo)、最大荧光(Fm)、(Φ)PSⅡ、ETR、qP和非光化学效率(NPQ)均高于FPRI.APRI和FPRI的光合速率降低与气孔因素有关,FPRI光合速率降低还与PSⅡ结构损伤有关；局部根区灌溉提高了裸燕麦干旱胁迫逆境下的耐受能力,APRI有利于保持更高的光合速率.%The objective of this study was to provide experimental evidence for photosynthetic mechanism under drought stress and practical technique of water-saving irrigation in naked oat (Avena nuda L.). In a pot experiment with instrument to control root zone irrigation and water amount, the effects on relative chlorophyll content (SPAD), photosynthetic curves, and chlorophyll fluorescence parameters were compared among irrigation models of alternative partial root zone irrigation (APRI), fixed partial root zone irrigation (FPR1), and conventional total root zone irrigation (CTRI). Compared to CTRI, partial root zone irrigation, including APRI and FPRI treatments, decreased leaf SPAD, net photosynthetic rate (Pn), and carboxylation efficiency (CE); however, APRI had no obvious effects on reducing initial quantum efficiency (α), maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency of PSII (ΦPSII), apparent electron transport rate (ETR), and photochemical quenching coefficient (qP). The leaf SPAD of APRI was significantly enhanced compared to that of FPRI (P<0.05), and the maximum net photosynthetic rate (Pmax),α, light saturation point (LSP), light use efficiency (LUE), Ci/Ca, CE, CO2 saturation point (Ci,sat), Fo, Fm, ΦPSII, ETR, qp, and NPQ were all higher in APRI than in FPRI. The reduction of Pn in partial root zone irrigation treatments resulted from stomatal factors, and structural damage of photosynthetic system II (PSII) was found in FPRI treatment. Clearly, partial root zone irrigation can improve the tolerance ability of naked oat against drought stress; particularly, APRI has the effect to maintain higher Pn than FPRI.