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【Objective】In this experiment,the relationship between nitrogen and betaine and key enzymes of Ningxia Lycium barbarum by scientific design,implementation and related indicators determination,was determined,which provided a theoretical basis for the quality cultivation of Ningxia wolfberry.【Method】In this experiment,three factors randomized block design was used to study Ningqi 1 astested material.The effects of nitrogen on the content of betaine and the key enzymes of metabolism in Ningxia Lycium barbarum at different growth stages were studied based on three factors including nitrogen depth,basal dressing ratio and nitrogen level.【Result】The content and yield of betaine,betaine aldehyde dehydrogenase and choline monooxygenase of Lycium barbarum were the highest when the depth of nitrogen fertilizer application was 0-20 cm.With the increase of depth,the content of betaine and two enzymes of Lycium barbarum decreased gradually.The content of betaine was the highest when the basal ratio was 3:1,and the highest was at 2:1:1.The contents of betaine aldehyde dehydrogenase and choline monooxygenase were the highest when the basal ratio was 3:1.With the increase of nitrogen application rate,the content of betaine and two enzymes decreased,while the yield increased.The yield ofLycium barbarum was the most suitable at 40 kg/667 m2,which was 88.13 %,29 %,3 % higher than that of no fertilization and 30 and 50 kg/667 m2,respectively.【Conclusion】Rational application of nitrogen fertilizer can significantly improve the yield and quality ofLycium barbarum.Comprehensive analysis showed that the nitrogen application at 40 kg/667 m2 and 0-20 cm depth promoted the accumulation of yield,betaine and key metabolic enzymes,and the accumulation of two enzymes was obvious at the ratio of base topdressing to top dressing at 3:1. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to explore the effects of different nitrogen application rates on the gene levels of betaine and key enzyme contents in Lycium barbarum, and provide technical support for the quality generation cultivation of L. barbarum in Ningxia. [Method] In the experiment, Ningqi No. 1' was used as the experimental material, and the split-plot experiment design was used. The main area was two treatments of nitrogen fertilizer application depth A (A1: 0-20 cm, A2: 20-40 cm), and the sub-area was five treatments of nitrogen application amount B (CK: 0 kg/666.7 m², B1: 15 kg/666.7 m², B2: 30 kg/666.7 m², B3: 45 kg/666.7 m², B4: 60 kg/666.7 m²). Through the determination of related indicators during the growth period of L. barbarum and the high-throughput transcriptome sequencing analysis of L. barbarum samples with different nitrogen levels, the effects of nitrogen on betaine and key metabolic enzymes in L. barbarum were clarified. [Result] With the increase of nitrogen application rate, the contents of betaine and its synthesis-related enzymes in L. barbarum were basically on the rise. When the concentration reached 45 kg/666.7 m², the contents of the measured indexes began to decrease. A total of 98 264 genes were obtained by transcriptome sequencing, including 10 081 differentially expressed genes. GO annotation analysis showed that the annotated genes were mainly enriched in photosynthesis, apoplast, monooxygenase activity, chlorophyll, tetrapyrrole binding enzyme activity and other processes. After KEGG annotation, it was found that the differential gene signal patnway was significantly enriched in plant hormone signal transduction, plant pathogen interaction and ribosome. The differentially expressed genes related to betaine synthesis were analyzed, and it was found that the expression levels were up-regulated to varying degrees. Comprehensive analysis of the relationship between the content of the measured indicators and the results of gene expression levels showed that the up-regulation of betaine synthesis-related enzyme genes led to changes in betaine content in L. barbarum fruits. [Conclusion] The key enzymes of betaine synthesis are monooxygenase and betaine aldehyde dehydrogenase. With the increase of nitrogen application rate, the content of key enzymes in betaine synthesis and the number of related genes are up-regulated, resulting in the increase of betaine content in L. barbarum fruit. [ABSTRACT FROM AUTHOR]