The Effect of Reduced Nitrogen Fertilizer Application on _japonic_ Rice Based on Volatile Metabolomics Analysis  
[PERSON]  
1 School of Health Science and Engineering, University of Shanghai for Science and Technology,  
Shanghai 200093, China; 157128064800163.com  
[PERSON]  
2 Academy of National Food and Strategic Reserves Administration, Beijing 100037, China; [EMAIL_ADDRESS] (Q.W. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (X.D.) 2  
[PERSON]  
2 Academy of National Food and Strategic Reserves Administration, Beijing 100037, China; [EMAIL_ADDRESS] (Q.W. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (X.D.) 2  
[PERSON]  
2 Academy of National Food and Strategic Reserves Administration, Beijing 100037, China; [EMAIL_ADDRESS] (Q.W. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (X.D.) 2  
[PERSON]  
1 School of Health Science and Engineering, University of Shanghai for Science and Technology,  
Shanghai 200093, China; 157128064800163.com  
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milling, appearance, cooking, eating, and nutritional properties. Among these, rice's eating quality is the most important characteristic, as it determines the price of rice in the market and influences customer satisfaction [12]. Taste and aroma are some of the most important factors of high-quality rice and determine whether rice is accepted by the public or not [13; 14]. Rice with a better aroma and flavor is more likely to be accepted by consumers and will command a higher price in the market. Therefore, the evaluation and research of rice flavor play an important role in promoting both competition in the rice market and agricultural economic development. Existing research on rice aroma has largely focused on preliminary analyses of the volatile compounds in rice or the characterization of its flavor quality using chromatography. In terms of objective evaluation, in addition to flavor analyzers and electronic noses, gas chromatography (GC) combined with corresponding pretreatment techniques and detectors with different characteristics has been widely explored and applied. With the invention, development, and application of gas chromatography, more specifically the establishment of GC-mass spectrometer (GC-MS) technology, research on rice flavor has made great progress [15; 16; 17]. Researchers [18; 19] have analyzed the flavors in rice using GC-MS, established systems for evaluating rice flavor, and identified more than 500 volatile compounds in rice via GC-MS and other chromatographic techniques [13]. Volatile aromatic compounds in rice include aldehydes, ketones, organic acids, alcohols, esters, hydrocarbons, phenols, pyrazines, and pyridines [14; 20]. A select few volatile organic compounds give rice its overall aroma and play a major role in sensory characterization; such compounds are referred to as key aroma components. Among them, 2-acetyl-1-pyrroline (2-AP) was first reported in 1982 [21] and is considered a typical aromatic compound of rice due to its extremely low sensory threshold, strong popcorn aroma, and sweetness [22]. It has been detected only in aromatic rice and is a typical substance therein [23; 24]. That said, alternative key aroma components may be present at levels below the flavor threshold, and these compounds may interact with aromatic compounds to affect the overall flavor. In addition, aromatic compounds often present different flavor properties at different concentrations and may play a variety of roles in various aroma systems. Any rice aroma is influenced by the comprehensive performance of volatile organic compounds (VOCs) in different concentrations and interactions between compounds [25]. Nitrogen is critical for rice yield and quality, but its overuse can be detrimental to efficiency and the environment.