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Saturation (SI) and compensation (CI) irradiances [μmol(photon) m -2 s -1 ] were 383.00±18.40 and 12.95±0.42 for wild C. nitidissima (in mid-July) and 691.00±47.39 and 21.91±1.28 for wild C. sinensis, respectively. C. nitidissima is a shade tolerant species, whereas C. sinensis has a wide ecological range of adaptability to irradiance. Both wild and cultivated C. nitidissima demonstrated low maximum net photosynthetic rate, maximum carboxylation rate, maximum electron transfer rate, and SI, which indicated low photosynthesis ability of leaves that were unable to adapt to strong irradiance environment. Both C. nitidissima and C. sinensis demonstrated strong photosynthetic adaptabilty in new environments. Hence proper shading may raise photosynthetic efficiency of cultivated C. nitidissima and promote its growth.Additional key words: compensation irradiance; net photosynthetic rate; saturation irradiance.--

Background: Blueberry is well known for its high content of bioactive metabolites, including anthocyanins, flavonols, and phenolic acids. This study aims to systematically study the effect of exogenous ABA application on ripening fruits in fruit growth, quality and anthocyanins content. The ripening process of blueberry fruit is divided into six stages for further analysis.Results: In this article, nontarget metabolomics were performed to demonstrate the effect on metabolites level. Basic results showed that 1000 mg/ml ABA significantly promoted fruit ripening, accelerated fruit colouration and increased soluble solid and anthocyanins content. At the same time, the fruit firmness and the content of some bioactive metabolites were also reduced. In metabolites level, a total of 1145 metabolites and 575 metabolites were detected and annotated in the positive model and the negative model, respectively. Principal component analysis and endogenous ABA content shows the exogenous ABA application is mainly concentrated on the green fruit turning into red fruit, after which the effect begins to decrease. The important metabolites of flavonoid pathway were detected and the result shows that anthocyanins synthesis was increased and parts of other bioactive metabolites were decreased. Conlusion: After comprehensive assessments, we believe that 1000 mg/ml exogenous ABA will have positive impacts on blueberry fruit quality and economic benefits. This finding provides a reference for different cultivation methods to improve the anthocyanin content of blueberry. Also, it provides a good research foundation for the next step of precise breeding for specific active compound of blueberry.

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