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以西藏主栽春青稞品种喜马拉雅22为试验材料,于开花期,利用LI-6400XT光合仪分别测定了倒1叶、倒2叶、倒3叶的光合光响应曲线,应用直角双曲线模型(RH)、非直角双曲线模型(NRH)、直角双曲线修正模型(MRH)、指数模型(EM)、修正指数模型(MEM)拟合青稞不同叶位的光响应曲线,比较和分析各模型的拟合参数。结果表明:模型RH、NRH拟合的青稞倒1、倒2、倒3叶最大净光合速率(P_(nmax))均高于实测值,而模型EM拟合值均小于实测值;模型RH、NRH拟合的青稞倒1、倒2、倒3叶光饱和点(I_s)远小于实测值,而模型EM拟合值略小于实测值;模型MRH拟合的Pnmax、I_s均与青稞不同叶位叶片实测值接近。模型MEM由于光抑制项为负值,导致P_(nmax)和I_s无法计算。在高光合有效辐射条件下[PAR>1 200μmol photons/(m~2·s)],只有MRH拟合的青稞倒1、倒2、倒3叶光合光响应曲线与实测光响应曲线最为接近,且拟合优度最佳。5种模型的拟合效果为MRH>MEM>EM>RH、NRH。
Using the Himalayan 22, a major cultivated species of Tibetan springgrass, as the experimental material, the photosynthetic light response curves of the 1-leaf, 2-leaf and 3-leaf were measured by LI-6400XT at flowering stage. ), Non-rectangular hyperbolic model (NRH), rectangular hyperbolic modified model (MRH), exponential model (EM) and modified exponential model (MEM) Combined parameters. The results showed that the maximum net photosynthetic rate (P nmax) of the inverted Hypaconenidae 1, inverted 2 and inverted 3 leaf of the model RH and NRH was higher than the measured values, but the fitted values of the model EMs were less than the measured values. The RH, NRH fitted barley inverted 1, inverted 2, inverted 3 leaf light saturation point (I_s) is much smaller than the measured value, while the model EM fitted slightly less than the measured value; model MRH fitting Pnmax, I_s with different leaf positions The measured value of the leaf is close. The model MEM can not be calculated because P_ (nmax) and I_s are negative due to the light suppression term. Under the conditions of high photosynthetically active radiation (PAR> 1 200μmol photons / (m ~ 2 · s)], only the response curve of photosynthetic light response of the inverted barley 1, inverted 2, inverted 3 leaf of MRH fitted with MRH was the closest to the measured light response curve, And the best goodness of fit. The fitting effects of the five models were MRH> MEM> EM> RH, NRH.