Abstract:

To clarify the differences in the responses of different quality types of peanut kernel quality to nitrogen application rate,three peanut cultivars were used in this study,including high oil cultivar Yuanza 9102(YZ9102),high protein cultivar Zhuhua 2(ZH2),and conventional cultivar Yuhua 23(YH23).Five nitrogen application rates were established,including 0,75,150,225,and 300 kg/ha.The effects of nitrogen application rate on kernel nutritional quality,functional components,and volatile flavor compounds were investigated.The results showed that nitrogen application rate significantly affected the protein content and protein yield of peanut kernels.For three cultivars,the protein content and protein yield increased first and then tended to be stable with the increase of nitrogen application rate,225 kg/ha nitrogen treatment had the best overall performance.There were significant differences in protein content and protein yield among different varieties,both of which were the highest in ZH2.Nitrogen application rate also significantly affected oil content and oil yield.With the increase of nitrogen application rate,oil content generally decreased,whereas oil yield increased first and then tended to be stable or decreased slightly,150 kg/ha nitrogen treatment was better.There were significant differences in oil content and oil yield among different varieties,both of which were the highest in YZ9102.The proportions of oleic acid and linoleic acid markedly responded to nitrogen application rate.When nitrogen application rate ranged from 0 to 150 kg/ha,the proportions of oleic acid and linoleic acid changed substantially,but tended to be stable with further increase of nitrogen application rate.Sucrose content was mainly affected by variety,YH23 had the highest value,while the effect of nitrogen application rate was not significant.In terms of functional components,resveratrol content decreased with the increase of nitrogen application rate,whereas resveratrol yield increased first and then decreased.For YZ9102 and ZH2,the optimal nitrogen application rate for resveratrol yield was 150 kg/ha.Among cultivars,ZH2 had the highest resveratrol content and yield.Calycosin content showed clear differences among growth stages and varieties,and increased rapidly at 90 days after flowering.For YH23,calycosin content was the highest under 75 kg/ha nitrogen treatment.A total of 47 volatile flavor compounds were identified by GC-IMS.Compared with the no-nitrogen treatment,esters and some alcohols showed relatively clear responses under 75 kg/ha nitrogen treatment,involving compounds such as ethyl acetate,methyl acetate,ethyl propionate, and 1-pentanol;under 150 kg/ha nitrogen treatment, aldehydes, ketones, alcohols, and some nitrogen-containing heterocyclic compounds showed pronounced responses, including 2,3-butanedione, 2,3-pentanedione, acetoxyethanol, tetramethylpyrazine, pyridine, and 2-methylbutanol;under the 225 kg/ha nitrogen treatment,some compounds with high retention times or specific odor characteristics showed distinct responses,including dimethyl disulfide,2-ethylfuran, ethylbenzene, o-xylene,n-butylcyclohexane,ethyl 2,3-dihydrocinnamate,and butyric acid.Comparisons among varieties showed that YZ9102 exhibited prominent responses in aldehydes, alcohols, and ketones related to lipid oxidation;ZH2 showed marked responses in esters,alcohols,and sweet aroma-related ketones;YH23 displayed distinct responses in heterocyclic compounds,sulfur-containing compounds,and compounds associated with specific odors.Overall,the response of peanut kernel quality to nitrogen application rate varies by quality indicator and cultivar,nitrogen application rate of 225 kg/ha is suitable for improving protein quality,whereas 150 kg/ha is more appropriate for regulating oil quality,and the optimization of nitrogen application rate for functional components and flavor quality needs to be combined with cultivar characteristics.

Key words: Peanut, Nitrogen application rate, Different quality types, Quality, Volatile flavor compounds

CLC Number: 

• S565