柱型苹果突变体叶片解剖结构及光合特性观察

Observation on leaf anatomy structure and photosynthetic characteristics of columnar apple(Malus × domestica Borkh.) mutants

柱型苹果因其显著特征是果树省力化栽培树型品种选育的珍贵资源。本文以4组柱型苹果突变体为试材,对其叶片解剖结构及光合特性的相关参数进行了观察和测定,结果表明,柱型苹果叶片颜色浓绿,叶片较大,其重量、厚度、叶绿素含量（SPAD）、栅栏组织厚度和栅海比均显著大于普通型苹果。普通型苹果叶片中每层栅栏组织细胞大小一致,且排列整齐紧密,而柱型苹果栅栏组织细胞排列相对杂乱。在一天的光合日变化中,柱型和普通型苹果的净光合速率（Pn）、蒸腾速率（Tr）均高于普通型苹果,二者均呈明显的双峰曲线,12：00出现明显的光合午休现象。在固定LED光源下,柱型苹果净光合速率（Pn）高于普通型,分别是普通型的1.1~1.3倍。柱型苹果荧光参数值（Fv/Fm）均低于普通型苹果,表明柱型苹果在转化光合产物过程中以荧光形式散失的能量少,有助于光合产物的积累,利于早果和丰产。

The columnar apple tree is a valuable resource for genetic improvement of cultivated apples due to its special architecture. In this paper, using four groups of columnar mutants as materials, the leaf structure was observed, and the photosynthesis and fluorescence parameters of the leaves were measured. The results showed that, the leaf color of each columnar type apple was dark green and the leaf area was more bigger, and the weight, thickness, chlorophyll content（SPAD） of the leaf, palisade tissue thickness and palisade tissue/spongy parenchyma（P/N） were significantly higher than those of the standard apple. The size of each layer palisade tissue cells in the standard apple leaves was consistent, and its arrangement was closely and regular. While the arrangement of the palisade tissue cells in column apple was relatively disorderly and irregular. Within the daily variations of leaf photosynthetic, the net photosynthetic rate（Pn） and transpiration rate（Tr） of the columnar apple were all significantly higher than those of the standard apple, and the daily variations of Pn and Tr both showed a double peak curve in columnar and standard apple. At 12：00 columnar and standard apple all appeared obviously photosynthetic midday depression. Under the fixed LED light source, the net photosynthetic rate（Pn） of the columnar apple in the same group was higher than that of the standard apple, which was 1.1–1.3 times of the standard apple. The fluorescence parameters value（Fv/Fm） of the columnar apple were all lower than those of the standard apple, which showed that the transformation of photosynthetic products with fluorescence loss less energy in columnar apple, and showed that the tree architecture of columnar apple is helpful to the accumulation of photosynthetic products and for early fruit and high yield.