Dualex植物多酚-叶绿素仪:钾肥对柑橘果实裂果影响的生理代谢综合分析

钾（K）营养在缓解果树果实的各种果皮障碍方面起着关键作用，但这种营养对柑橘果实分裂相关的生理和代谢特征的影响尚不清楚。用三种水平的钾处理了果实容易裂开的杂交品种‘Ehime Kashi 34’（citrus Nishinoka×C.Shiranui）。结果表明，施用钾肥处理的根系增加了果皮和果肉中钙（Ca2+）、氮（N）、钾的含量、果皮与果肉的硬度比、光合速率、气孔导度和细胞间CO2浓度。相反，它降低了叶片的相对叶绿素指数和Ca2+含量。同时，经K处理后，在果皮和果肉中分别检测到59和13种差异表达代谢物（DEM）。其中，5种化合物积累上调，包括果皮中各种氨基酸的合成和果肉中各种糖苷代谢物的积累，这些代谢物被上调。赤霉素和糖苷的积累水平被下调。这可能是钾缓解果实分裂的主要原因。

关键词：钾；柑橘；果实裂开；生理学；代谢物

Integrated Physiological and Metabolomic Analyses of the Effect of Potassium Fertilizer on Citrus Fruit Splitting

Abstract

Potassium (K) nutrition plays a key role in alleviating a variety of peel disorders in tree fruit, but the effect of this nutrient on the physiological and metabolic profiles involved in the fruit splitting of citrus remains unclear. Three levels of K were used to treat citrus ‘Ehime Kashi 34’ (Citrus Nishinoka × C. Shiranui), a hybrid cultivar with fruit that easily split. The results showed that the roots of the treatment with K fertilizer increased the contents of calcium (Ca2+), nitrogen (N), and K in the skin and flesh, the fruit firmness ratio of the peel to the flesh, photosynthetic rate, stomatal conductance, and concentration of intercellular CO2. In contrast, it decreases the relative chlorophyll index and content of Ca2+ in the leaves. Simultaneously, 59 and 13 differentially expressed metabolites (DEMs) were detected in the peel and flesh, respectively, after treatment with K. Of them, five compounds were upregulated, including the synthesis of various amino acids in the peel and the accumulation of various glycoside metabolites in the flesh which were upregulated. The accumulation of levels of gibberellin and glycoside were downregulated. That could be the main reason why potassium alleviates fruit splitting.

Keywords: potassium; citrus; fruit splitting; physiology; metabolite