喷施钾、钙和铁肥调控荔枝果色的效果及机制OA

Aiming at the production problem of pale pericarp and poor marketability of Xianjinfeng litchi,this study explored the regulatory effects and physiological and molecular mechanisms of foliar application of potassium fertilizer(KCl,K2SO4),calcium fertilizer(CaCl2)and iron fertilizer(EDTA-Fe)on its pericarp pigmentation.Using 5-year-old Xianjinfeng litchi plants as test materials,the corresponding fertilizers were sprayed three times at the fruit expansion stage.The mineral element content,phenolic components,key enzyme activities related to anthocyanin synthesis in pericarp were determined,and the differential expression of related genes was analyzed combined with transcriptomic sequencing.The results showed that compared with the water control,0.1%CaCl2 and 0.02%EDTA-Fe treatments sig-nificantly increased pericarp Ca and Fe contents by 18.2%and 22.7%,respectively,and significantly reduced pericarp Mn accumulation.The pericarp PAL activity of EDTA-Fe treatment significantly increased by 32.6%compared with the control,the UFGT activity of CaCl2 and EDTA-Fe treatments increased by 47.2%and 51.8%,respectively,and the GST activity increased by 42.5%and 45.3%,respectively.The contents of cyanidin-3-glucoside and cyanidin-3-rutinoside in pericarp of CaCl2 treatment significantly increased by 38.7%and 42.1%,respectively,and the content of cya-nidin-3-rutinoside in EDTA-Fe treatment significantly increased by 35.4%.At the same time,both treatments signifi-cantly increased the contents of co-pigments such as epicatechin,proanthocyanidin A2,quercetin-3-glucoside and fer-ulic acid,with increases ranging from 15.6%to 41.2%.Transcriptome analysis showed that CaCl2 and EDTA-Fe treat-ments could significantly up-regulate the expression of structural genes such as C4H,4CL,CHI,F3H,UFGT,GST in anthocyanin synthesis pathway,and key transcription factors such as MYB,bHLH,NAC,and regulate the expression of ion transport-related genes such as ACA and VIT,thereby reshaping pericarp cation homeostasis.However,0.2%KCl and 0.23%K2SO4 treatments did not significantly improve the pericarp pigmentation of Xianjinfeng,and significantly reduced the soluble solids and soluble sugar contents in pulp;CaCl2 and EDTA-Fe treatments had no negative effect on the core quality of fruits,and the pulp sugar-acid ratio of EDTA-Fe treatment was significantly increased by 14.8%compared with the control.In conclusion,foliar application of 0.1%CaCl2 and 0.02%EDTA-Fe can significantly im-prove the pericarp pigmentation of Xianjinfeng litchi by regulating the mineral element homeostasis of pericarp,acti-vating the activity of genes and enzymes related to anthocyanin synthesis and transport,and increasing the content of co-pigments,without impacting fruit internal quality,This approach can serve as a safe and efficient agronomic measure for fruit color regulation of this variety.