陇东乔化密闭苹果园树体特性及冠层微域环境对果园群体结构的响应机制研究

The technology of transform in orchard population structure is widespread applied in the production at present, but for the mechanism of improving quality and yield and the effects of leaf characteristics change did not delve into, especially in relationship between that change of the organization structure, inclusions, yield and quality that as main evaluation factors of tree leaf quality, Lack of necessary research and analysis. In order to investigate the effect of closed orchard on leaf characteristics change and have a scientific evaluation for the effects on tree leaf quality and production capacity. In this study, we’ll have a transform in the closed orchard 15 years old that in 450mm and 550mm rainfall plateau area, and have a observation for the canopy micro environment, leaf photosynthesis and fruit yield, and have a measure for the organizational structure index and inclusions index of leaf, and for the appearance index and inclusions index of fruit. Which so that we have a study of the influence about leaf characteristics and fruit quality and it’s driving factors by the transformation technology of closed orchard, and so that we have a analysis for the relationship between micro environment - leaf characteristics - fruit quality, and so that we can make clear the action mechanism of leave quality and tree’s production capacity about the transformation technology of closed orchard, and so that we can provide theoretical support for development and utilization of this technology.

苹果园群体结构调整技术在密闭果园改造中由于增效显著已被大面积推广应用，但对其提质增产机理及树体特性变化效应没有深入探讨，尤其在作为树体叶片质量状况主要评价因子的组织结构、内含物变化与产量品质关系等方面，缺乏必要的研究分析。为探明群体结构调整对冠层微域环境及树体叶片特性改变的影响，并科学评价该技术对树体叶片质量和生产能力的影响效应，本研究在大田试验条件下，分别在450mm和550mm降雨量的旱塬区对15年生树龄的乔化密闭苹果园进行群体结构调整，对树冠微域环境、叶片光合特性及果实产量进行观测，并在室内对叶片的组织结构指标、内含物指标，果实外观指标、内含物指标进行测定，研究密闭果园群体结构调整对苹果树体叶片特性和果实品质及其驱动因素的影响，分析微域环境-叶片特性-果实品质之间的关系，明确该项技术对叶片质量和树体生产能力的改善机理，为其完善发展和可持续开发利用提供理论支持。

本研究在4年大田定位试验条件下，以旱塬区乔化密闭苹果间伐改形原位跟踪试验为基础，通过观测树冠微域环境、叶片光合特性、组织结构、内含物、转录组、果实产量及品质，分析微域环境-叶片特性-果实品质之间的关系，研究密闭苹果园间伐改形对树体叶片特性和果实品质及其驱动因素的影响，探索间伐改形对叶片质量和树体生产能力的改善机理。研究结果表明：间伐改形后，冠层微域环境主要因子与对照差异显著，相对光强、温度分别比对照提高50.27%和1.21℃，相对湿度降低了2.36个百分点，并且分布更趋均匀合理；叶片光合主要指标的净光合速率、蒸腾速率、气孔导度比对照分别提高了12.6%、7.3%和17.1%，胞间CO2浓度降低了7.1%，差异均显著；叶绿素荧光主要指标最大荧光产量、非光化学猝灭系数、φEo和ψO显著优化，分别比对照提高1.52%、2.15%、11.32%和8.23%，光合潜能明显增大；叶片厚度、栅栏组织厚度和海绵组织厚度分别比对照提高了5.41%、9.23%和4.33%；参与促进光合作用的叶绿素等相关内含物及酶活性显著提高，叶绿素、RUBP、ATP、GSH、APX、DHAR和GR活性分别提高8.70%、12.18%、20.77%、16.27%、7.42%、16.08%和16.42%。抑制光合同化作用的脱氢抗坏血酸等相关内含物及酶活性显著降低，DHA、GSSG、抗坏血酸氧化物酶和多酚氧化物酶活性分别降低11.00%、13.16%、12.29%和12.44%。光合潜能显著提高；果实品质主要指标与对照差异显著，单果重和着色面积分别比对照提高了33.5%和20.9%，可溶性固形物含量由对照的14.00%提高到14.95%；转录组测定发现，间伐改形后，光捕获天线蛋白LHCB1、LHCB2、LHCB3、LHCB4和LHCB6表达量显著提升，Mg螯合酶亚基chld表达量显著上调，组成真核生物光系统Ⅱ（PSⅡ）的放氧复合物7个核基因之一的PsbQ也显著上调，进而提高了树体整体的光合能力。最终研究表明，果园间伐改形后树体光能利用效率的提高是由外因（冠层微域环境因子的改善）和内因（叶片栅栏组织厚度、叶绿素含量、光合酶活性、光合相关的基因表达量等指标的显著提升）共同协作完成的。研究成果为乔化密闭果园间伐改形技术的完善发展和生产实践提供理论支持和科学依据。