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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(ФPSII)、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)、ФPSII、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。
In order to investigate the physiological mechanism of photosynthetic capacity decline in bare oat (Avena nuda L.) under different irrigation patterns in local root zone, pot and water seepage plate were used to compare the effects of alternate root zone irrigation (APRI), fixed root zone irrigation (FPRI) Under conventional irrigation (CTRI), the relative chlorophyll content (SPAD value), photosynthetic characteristic curve and chlorophyll fluorescence kinetic characteristics of naked oat flag leaf were analyzed. Compared with the CTRI treatment, local root zone irrigation (including APRI and FPRI treatment) reduced leaf SPAD value, Pn and initial carboxylation rate (AP), but APRI treatment did not significantly reduce the initial quantum efficiency (α) , PSII maximum quantum efficiency (Fv / Fm), PSII actual photochemical efficiency (ФPSII), electron transfer efficiency (ETR) and photochemical efficiency (qP). APRI significantly increased the leaf SPAD value (P <0.05) compared with FPRI, and the maximum net photosynthetic rate (Pmax), α, light saturation point (LSP), light energy utilization rate LUE, Ci / Ca, CE, Ci sat, initial fluorescence, maximum fluorescence, ФPSII, ETR, qP and non-photochemical efficiency (NPQ) were all higher than those of FPRI. The decrease of photosynthetic rate of APRI and FPRI was related to stomatal factors, and the decrease of photosynthetic rate of FPRI was also related to the damage of PSII. Local root zone irrigation increased the tolerance of bare oats under drought stress and APRI was better for maintaining higher photosynthetic rate.