Clarifying the characteristics of photoassimilates transport and distribution to the fruits from leaves located on different branches can guide the branch composition and pruning of apple trees. A field experiment was carried out in 6-year-old ‘Fuji’3/M26/ Malus hupehensis Rehd. apple trees, and the 13 C-labeled tracer method was used to study the growth characteristics of the leaves on different branches (vegetative branches, long branches, mid branches, short branches, bourse branches, and cluster branches) and the translocation of 13 C-photoassimilates to the fruit from these leaves at the fruit enlargement stage in 2018 and 2019. Additionally, the effect of the distance between the leaf and fruit (leaves from both short and long branches that were 20, 40, and 60 cm away from the fruit) was assessed. We found that with increased branch length, the intensity of photosynthesis and the level of photoassimilates synthesis in the leaves decreased, but increased in the leaves near the fruits. Indole-3-acetic acid, gibberellic acid, and zeatin accumulated in the leaves of the longer branches, while abscisic acid accumulated in the leaves of the shorter branches. The δ values of the 13 C-labeled leaves from the short branches, the short branches 20 cm away from the fruits (S20), and the bourse branches at the fruit stage were low, and the corresponding δ values of the fruits were high. The 13 C absorption of the fruit was highest in the leaves of the short branches, followed by those of the bourse branches, S20, and mid branches, and was lower in the leaves of the vegetative branches, cluster branches, and 60 cm short and long branches. The leaf 13 C-photoassimilates in the short branches were more greatly transported to the fruits than those from the long branches when the distance between the leaves and fruits was the same. The 13 C absorption of the fruit increased by 10.91, 5.28, and 1.14 mg at the leaf–fruit spacing of 20, 40 and 60 cm, respectively, and the leaf–fruit spacing was determined to be more important than branch type in determining the 13 C absorption of the fruit.

中文翻译：

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苹果不同分枝位置叶片光同化物对果实的运输和分布特征

阐明光同化物从不同枝条上的叶子向果实的运输和分布特征，可以指导苹果树的枝条组成和修剪。在6年生'富士'3/M26/Malus hupehensis Rehd进行田间试验。用 13 C 标记示踪剂法研究不同枝条（营养枝、长枝、中枝、短枝、交枝、丛枝）叶片的生长特性及 13 C 的易位- 在 2018 年和 2019 年果实膨大阶段，这些叶子对果实进行光同化。此外，叶与果实之间距离的影响（来自距果实 20、40 和 60 厘米的短枝和长枝的叶子）果）进行了评估。我们发现随着分支长度的增加，叶片中光合作用强度和光同化物合成水平降低，但在果实附近的叶片中增加。Indole-3-乙酸、赤霉酸和玉米素在较长枝条的叶子中积累，而脱落酸在较短枝条的叶子中积累。13 C标记的短枝、距果实20 cm处(S20)短枝和交枝的13 C标记叶片δ值较低，果实对应的δ值较高。果实对 13 C 吸收在短枝叶中最高，其次是交生枝、S20 和中枝，而在营养枝、丛生枝和 60 cm 短枝和中枝的叶子中吸收的 13 C 较低。长长的树枝。当叶与果实的距离相同时，短枝叶13 C-光同化物比长枝叶13 C光同化物向果实的运输量更大。在叶-果间距为20、40和60 cm时，果实的13 C吸收量分别增加了10.91、5.28和1.14 mg，并且确定了叶-果间距比枝条类型更重要。 13 C 吸收果实。