不同短截程度对苹果枝条修剪反应及新稍叶片光合特性的影响

Effects of various cutting back degree on pruning and photosynthetic characteristics of new shoot leaves in apple trees

为研究不同短截程度对苹果修剪反应以及新梢叶片光合特性的影响,以5年生‘富士’(Malus Domestica Borkh cv.Fuji)苹果树为试材,在休眠期对一年生外围延长枝条进行不同程度的短截,观察枝条的修剪反应,测定新梢叶片的叶绿素含量及叶片形态特征、光合参数、叶绿素荧光参数。结果表明:1)随短截程度的加重,枝条萌芽率降低,成枝力增大,抽发长枝比率明显增加,叶绿素a含量增加;延长枝增长增粗,延长枝重量、节间数、春秋稍长度显著增加。2)净光合速率、蒸腾速率随短截程度加重明显增大,这可能是短截之后新梢叶片叶肉细胞本身光合能力增强导致。3)最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)也随短截程度的加重而增大,电子传递更快,用于CO2同化的能量较多;相反,非光化学猝灭(NPQ)随短截程度加重而降低,用于热散失消耗的较少。

In this study,effects of various cutting back degree on pruning and photosynthetic characteristics of new shoot leaves were examined by using 5-year-old‘Fuji＇apple（Malus Domestica Borkh cv.Fuji）.Within the same tree,during dormancy period,the 1-year-old surrounding extended shoots were treated with cutting back in different degree.The pruning responses of branches such as the content of chlorophyll,the morphology of leaves,leaf photosynthesis and chlorophyll fluorescence were measured after treatments.The results showed that：1）Cutting back increased the branching rate,the long branch rate,the content of chlorophyll a,the length,diameter,weight,internode number,length of spring and autumn shoots of extended branches,whereas the germination rate was decreased;2）Cutting back affected the net photosynthetic rates and transpiration rate positively,which probably because cutting back improved the photosynthetic capacity of mesophyll cell;3）The PSⅡ maximal photochemical efficiency（Fv/Fm）,the PSⅡactual photochemical efficiency（ΦPSⅡ）and the photochemical quenching（qP）increased after cutting back.The more the cutting back degree,the greater the efficiency increase..Hence,the electron transferred faster,and more energy was provided for CO2 assimilation.On the contrary,the non-photochemical reaction（NPQ）decreased along with the cutting back degree due to less heat for consumption.