矮化砧及对应中间砧苹果叶片光合对光照和CO_(2)响应的模型模拟与评价

Model Simulation and Evaluation of Photosynthetic Responses of Apple Leaves of Dwarf Rootstocks and Corresponding Interstocks to Light and CO_(2)

为了阐明矮化砧木调控苹果叶片光合作用对光照度和CO_(2)响应的机制,筛选适宜的苹果叶片光合模型,以8 a生‘长富2号’苹果为试材,设置4种砧木处理:M9、M26、M9/八棱海棠和M26/八棱海棠。结果表明:各个模型均可用于模拟不同砧木苹果叶片光合-光响应(P_(n)-PAR)和光合-二氧化碳(P_(n)-CO_(2))响应过程,决定系数(R^(2))均大于0.99。非直角双曲线模型(NRH)对M9/八棱海棠和M26/八棱海棠叶片的P_(n)-PAR曲线模拟的R^(2)最大,均方根误差(RMSE)和平均绝对误差(MAE)最小,直角双曲线修正模型(MRH)对M9和M26叶片的P_(n)-PAR曲线模拟的R^(2)最大,RMSE和MAE最小,且MRH模型对各处理的P_(n)-CO_(2)曲线模拟精度最高。与实测值相比,基于MRH模型的光合参数估计值相对误差最小,且获得的参数信息最全面,NRH模型次之。M26和M26/八棱海棠的初始量子效率、最大净光合速率、光饱和点、羧化效率、光呼吸速率高于M9和M9/八棱海棠,而光补偿点、CO_(2)补偿点、暗呼吸速率低于M9和M9/八棱海棠,说明M26对弱光和低CO_(2)浓度的利用效率高,耐弱光能力强,呼吸消耗少。结论:基于叶片尺度光合模型的砧木光合能力评价可优先考虑使用NRH和MRH模型。M26在作为基砧及中间砧的叶片光合能力优于M9。

The aim of this study is to clarify the role of dwarf rootstock in regulating the photosynthetic response of apple leaves to light intensity and CO_(2) and to construct suitable photosynthetic models.The cultivar ‘Naga Fu 2’ and four rootstock-scion combinations(M9,M26,M9/Baleng,and M26/Baleng) of 8-year-old trees were used in the study.The results showed that all the models constructed in this study had qualified accuracy in simulating the response of photosynthesis to light(P_(n)-PAR) and carbon dioxide(P_(n)-CO_(2)).The determination coefficients(R^(2)) of all the models were higher than 0.99.The non-rectangular hyperbolic(NRH) model had a greater R^(2) and smaller mean square error(RMSE) and mean absolute error(MAE) than the other models in simulating P_(n)-PAR response of M9/Baleng and M26/Baleng apple leaves.The modified rectangular hyperbolic(MRH) model had a greater R^(2) and smaller RMSE and MAE than other models in simulating P_(n)-PAR response of M9 and M26 leaves.The MRH model had highest accuracy in simulating P_(n)-CO_(2) under the all treatment compared with other models.The relative error of the predicted values of photosynthetic parameters was smaller than that of measured values based on MRH model,and the MRH model produced the most reasonable information of photosynthetic parameters,followed by the NRH model.The initial quantum efficiency,maximum net photosynthetic rate,light saturation point,carboxylation efficiency,and light respiration rate in M26 and M26/Baleng apple leaves were higher and the light compensation point,CO_(2) compensation point,and dark respiration rate were lower than those in M9 and M9/Baleng apple leaves,indicating that M26 had higher light and CO_(2) utilization efficiency,strong resistance to low light intensity and lower respiration consumption in M9 apple leaves.In conclusion,the results showed that NRH and MRH are appropriate candidate models for evaluating photosynthetic capacities of apple leaves of different rootstocks and interstocks.Leaf photosynthetic capacities of M26 are better than those of M9.