ABSTRACT
Nitrogen application at the booting stage affects 2-acetyl-1-pyrroline, proline, and total nitrogen contents in aromatic rice

Zhaowen Mo1, 2, Umair Ashraf1, 3, Yongjian Tang1, 2, Wu Li4, Shenggang Pan1, 2, Meiyang Duan1, 2, Hua Tian1, 2, and Xiangru Tang1, 2*
 
Aromatic rice (<em">Oryza sativa L. subsp. japonica Kato) is globally popular due to its pleasant aroma and enchanting flavor. 2-Acetyl-1-pyrroline (2-AP) is recognized as the only major flavoring compound in aromatic rice. Plant nutrition affects the production and accumulation of 2-AP in rice, but the effect of time-specific nutrient application during the developmental phases of rice on 2-AP has not yet been reported. Three N levels (N0: 0 kg ha-1, N1: 30 kg ha-1, and N2: 60 kg ha-1) at the booting stage were applied to a popular aromatic rice cv. Yungengyou 14, to assess the accumulation pattern of 2-AP, proline, and N as well as relationships among the investigated indices regarding 2-AP accumulation. Among all other plant parts, the highest 2AP contents were found in ear axes and flag leaves, i.e. 17.04%-18.26% and 14.37%-15.05% at 17 as well as 18.41%-22.74% and 14.38%-15.75% at 30 DAF under all N-levels. Interestingly, N application at the booting stage also maintained higher proline and 2-AP contents in different plant tissues during the early grain filling stage. Hence additional N dose at booting stage could improve the grain aroma contents of aroma rice while considering the amount of N fertilizer added.
Keywords: Aroma, Oryza sativa subsp. japonica, nitrogen, plant tissues, 2-AP.
1South China Agricultural University, College of Agriculture, Guangzhou, 510642, Guangdong, China.
*Corresponding author (tangxr@scau.edu.cn).
2Ministry of Agriculture P.R. China, Scientific Observing and Experimental Station of Crop Cultivation in South China, Guangzhou, 510642, Guangdong, China.
3University of Agriculture, Department of Agronomy, Faisalabad, 38040 Pakistan.
4Crops Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, Guangdong, China.