树形调整对香榧树冠光照强度和种实品质的影响

Effects of tree shape adjustment on canopy light intensity and seed quality of Torreya grandis ‘Merrillii’

【目的】研究不同树形调整对香榧Torreya grandis‘Merrillii’树冠光照强度和光合速率的影响,阐明不同骨干枝数目和开张角度处理下香榧种实中碳水化合物、油脂等变化规律,揭示树形调整对香榧种实品质的影响,为香榧树形培养、提质增效提供科学依据。【方法】设置不同骨干枝数目和骨干枝开张角度单因素和交互处理试验,测定树冠光照强度、叶片光合速率,分析可溶性糖、淀粉、可溶性蛋白质量分数、含油率及脂肪酸组分变化。【结果】骨干枝开张角度调整对香榧树冠光照强度有显著影响。与对照相比,60°处理下5—9月香榧树冠中层和下层的光照强度显著增加(P<0.05),7月树冠中层光照强度最高达到40 klx,但80°开张角度则会降低树冠光照强度。同时,骨干枝数目和开张角度的交互处理下,5、7和9月香榧叶片净光合速率、气孔导度、蒸腾速率均显著提高(P<0.05)。碳水化合物检测发现,3和4条骨干枝与60°开张角度(N3-A60°和N4-A60°)处理下香榧种实中可溶性糖和淀粉质量分数显著增加(P<0.05),5月香榧种实可溶性糖和淀粉质量分数分别达到609.05和576.63 mg·g^(−1)。树形调整也显著促进了香榧种实中可溶性蛋白和油脂的积累(P<0.05)。【结论】树形调整对香榧树冠光照强度、叶片光合能力和种实品质有明显的促进作用,其中以3和4条骨干枝与60°开张角度处理最佳。

[Objective]This study aimed to investigate the impact of adjusting the number and opening angle of skeleton branches of Torreya grandis‘Merrillii’on canopy light intensity and leaf photosynthesis.Additionally,it aimed to elucidate alterations in carbohydrate,oil content,and other components to reveal the effect of tree shape adjustment on seed quality and provide a scientific basis for the tree cultivation.[Method]Experiments with different numbers and opening angles of skeleton branches were conducted using single-factor and interactive treatments to examine canopy light intensity,leaf photosynthesis,and the contents of soluble sugar,starch,soluble protein,oil and fatty acid components.[Result]Adjusting the opening angle of skeleton branches significantly influenced canopy light intensity.Under the opening angle of 60°,the light intensity in the central and lower layers of the canopy notably increased(P<0.05)from May to September,peaking at 40 klx in the central layer in July.However,an excessively wide opening angle of 80°led to a decrease of canopy light intensity.Under the interactive treatment of different numbers and opening angles of skeleton branches,the net photosynthetic rate, stomatal conductance, and transpiration rate of the leaves significantly increased in May, July and September (P<0.05). Carbohydrate analysis revealed that the contents of soluble sugar and starch in seeds under 3 and 4 branches with the opening angle of 60° adjustment (N3-A60° and N4-A60°) were significantly increased (P<0.05). The content of soluble sugar and starch in the seeds reached 609.05 and 576.63 mg·g−1, respectively. Furthermore, tree shape adjustment significantly promoted the accumulation of soluble protein and oil in the seeds. [Conclusion] The tree shape adjustment of T. grandis ‘Merrillii’ can enhance the canopy light intensity, leaf photosynthesis and seed quality, and the 3 and 4 skeleton branches with the opening angle of 60° has the best promotion effect. [Ch, 2 fig. 7 tab. 38 ref.]