| Wolfberry is one of the nine advantageous characteristic industries in Ningxia,and selenium-enriched wolfberry has become a new direction for the vigorous development of Ningxia’s wolfberry industry in the future.However,as an emerging industry of selenium-enriched wolfberry,Ningxia has not yet issued relevant policy standards for selenium-enriched wolfberry,and lacks scientific and standardized management of selenium-enriched wolfberry.Using 5-year-old "Ningqi No.1" wolfberry as material,the effects of exogenous selenium species and nano-selenium application concentration on physiological regulation of wolfberry and the effect of selenium on fruit quality,metabolites and fruit mineral element content of wolfberry were studied.The main findings are as follows:1.Foliar spraying of exogenous selenium can significantly increase the photosynthetic index,chlorophyll content and protective enzyme activity of wolfberry barbarum leaves.Nano-selenium can significantly increase intercellular CO2 concentration,stomatal conductance,net photosynthetic rate and transpiration rate,significantly increase chlorophyll a,chlorophyll b and carotenoid content in wolfberry leaves,effectively reduce malondialdehyde content,and increase superoxide dismutase.and catalase activity;organic selenium can significantly improve water use efficiency and leaf peroxidase activity.Exogenous selenium can significantly improve the morphological index,yield,quality of wolfberry fruit and the mineral elements of each organ of wolfberry.Among them,nano-selenium significantly improved the transverse diameter,longitudinal diameter,fruit shape index,single grain weight and yield of wolfberry fruit,increased the content of titratable acid,reducing sugar,and vitamin C,and significantly increased plant potassium,phosphorus,calcium,and iron.,selenium content,and the average fruit selenium content is 5.92 ug·100g-1,which can meet the requirements of human body selenium supplementation;organic selenium significantly improves the soluble solid content of fruit;through principal component analysis and comprehensive evaluation,the comprehensive ranking is:Nano selenium>organic selenium>sodium selenite>spray water.2.Differential metabolites mainly include amino acids and their derivatives,flavonoids,flavonoids and alkaloids.Among them,after spraying sodium selenite,2 kinds of amino acids and their derivatives were significantly up-regulated,3 kinds were significantly down-regulated;4 kinds of flavonoid metabolites were significantly down-regulated,4 kinds of flavonoid metabolites were significantly up-regulated;2 kinds of alkaloids were significantly up-regulated,1 alkaloids were significantly down-regulated.After spraying nano selenium,9 kinds of amino acids and their derivatives were up-regulated and 7 kinds were down-regulated;among flavonoid metabolites,only 2 kinds of flavonoid metabolites were up-regulated;5 kinds of alkaloids were significantly up-regulated,and 9 kinds of alkaloids were up-regulated significantly down.After spraying organic selenium,10 kinds of amino acids and their derivatives were up-regulated and 7 kinds were down-regulated;4 kinds of flavonoid metabolites,5 kinds of flavonoids,and 7 kinds of flavonoids were screened,of which 3 kinds were up-regulated and 9 kinds were down-regulated;among the 22 alkaloids,10 were significantly up-regulated,and 12 were significantly down-regulated.3.After spraying sodium selenite,6 differential genes were involved in peroxidase activity,41 differential genes were involved in catalytic activity,and 22 differential genes were involved in oxidoreductase activity;after spraying nano-selenium,273 differential genes were involved in organic nitrogen During compound metabolism,121 differential genes were involved in phosphorus metabolism,322 differential genes were involved in protein binding,and 197 differential genes were involved in adenylate binding;557 differential genes were involved in organic nitrogen compound metabolism after spraying organic selenium,There were 662 differential genes involved in protein binding and 738 differential genes involved in catalytic activity.The KEGG pathway analysis of the differential genes showed that the differential genes involved in sodium selenite treatment were significantly enriched in 13 pathways including the biosynthesis of secondary metabolites.Differential genes involved in nano-selenium treatment were significantly enriched in 20 pathways including amino acid biosynthesis.Differential genes involved in organic selenium treatment were significantly enriched in 20 pathways including carbon metabolism,amino acid biosynthesis and homologous recombination.Comparing the pathway enrichment analysis of transcriptome and metabolome,it was concluded that the differential genes and differential metabolites obtained by spraying sodium selenite were 5 common ones,such as flavonoid biosynthesis and amino sugar and nucleotide sugar metabolism.metabolic pathways.The differential genes and differential metabolites obtained by spraying nano-selenium compared with 10 common metabolic pathways including arginine and proline metabolism.There are 10 common metabolic pathways in the differential genes and differential metabolites obtained by spraying organic selenium,including arginine and proline metabolism,carbon fixation in photosynthetic organisms,and pentose phosphate pathway.4.200 mg·L-1 of nano-selenium can significantly improve the morphological index of fruit.Nano-selenium with a concentration of 300 mg·L-1 can effectively increase the contents of chlorophyll a and carotenoids,which are significantly increased by 80.00%and 206.25%compared with spraying water;and SPAD were the highest at the concentration of 100 mg·L-1,which increased by 76.54%and 5.36%,respectively,compared with spraying water.When the nano-selenium reached 300 mg·L-1,the activities of superoxide dismutase,catalase and peroxidase began to decrease with the increase of nano-selenium concentration;the malondialdehyde content was at the concentration of 200 mg·L-1 significantly decreased under treatment.5.The content of reducing sugar,total acid and Vc in the fruit is the best in 200 mg·L-1 300 mg·L-1 nano-selenium.The contents of potassium,phosphorus,magnesium,manganese,zinc and selenium in wolfberry were significantly increased by foliar spraying of nano-selenium,and the content of iron and calcium was significantly decreased.The content of various elements in the leaves of wolfberry is higher,and the content of elements in the fruit is less.The average fruit selenium content was 8.17 ug · 100g-1,which could meet the requirements of human body for selenium supplementation.The photosynthetic characteristics,resistance index,chlorophyll content,fruit quality and yield index of wolfberry leaves were comprehensively analyzed under the conditions of nano-selenium treatment,and the effect of nano-selenium at 200 mg·L-1 was the best.Foliar spraying of various selenium fertilizers can significantly improve the photosynthetic index,protective enzyme activity,fruit quality,morphological index,mineral element content and metabolites in wolfberry leaves.Nano-selenium has a good effect on improving the indicators of wolfberry.Nano-selenium at the concentration of 200 mg·L-1 can effectively improve the photosynthetic index,protective enzyme activity,fruit quality,morphological index and mineral element content of wolfberry leaves. |
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