Effects of Light Quality Treatments during the Grain Filling Period on Yield, Quality, and Fragrance in Fragrant Rice

Huijia Xie,Shenggang Pan,Xiangru Tang,Meiyang Duan,Xuwei Liu,Wenjun Xie,Shuli Wang,Hua Tian,Zhaowen Mo

doi:10.3390/agronomy11030531

Abstract

The effect of the light quality on 2-acetyl-1-pyrroline (2AP) during the grain filling period in fragrant rice has rarely been investigated. A pot experiment was carried out with two fragrant rice varieties, Xiangyaxiangzhan and Yuxiangyouzhan, grown under three light treatments, 100% red light (L1), 100% blue light (L2), and compound light (L3), during the grain filling period, and natural light was taken as the control (CK). The yield, quality, and fragrance were investigated. The results showed that light quality treatments significantly decreased the 2AP content in mature grains by 16.67–32.82% but improved the grain yield by 2.70–21.41% compared to CK. The regulation effects of light quality treatments on grain yield and 2AP are linked to yield-related traits, biomass accumulation, antioxidant physiology, and 2AP formation-related physiology. Additionally, light quality treatments decreased the chalky rice percentage and chalkiness, and increased the length-to-width ratio. Overall, light quality treatments during the grain filling period had a positive effect on the grain yield but not on fragrance in fragrant rice.

Highlights

Rice is one of the most popular food crops in the world, and fragrant rice is a specific rice type with high economic value and broad market prospects due to its fragrance and delicacy [1]
Studies have reported that it contains lots of volatiles, of which 2-acetyl-1pyrroline (2AP) is generally considered to be the most important compound for fragrance in the grain of fragrant rice [2,3]
Fragrant rice has a lower grain yield than non-fragrant rice, and one study has suggested that the fragrance in fragrant rice is related to the reduction of grain yield under salt treatment [8]

Summary

Introduction

Rice is one of the most popular food crops in the world, and fragrant rice is a specific rice type with high economic value and broad market prospects due to its fragrance and delicacy [1]. Previous studies have reported crop management practices, such as application of plant growth regulators [9,10], silicon [11], nitrogen [12], water–nitrogen interaction [13,14], and selenium–silicon interaction [15] effect on both grain yield and fragrance in fragrant rice. Those studies suggested that proline, 1-pyrroline-5-carboxylate (P5C), γ-aminobutyric acid (GABA), as related substances of 2AP synthesis, are highly related to aroma synthesis of fragrant rice. The regulation of grain yield under low light intensity could be associated with changes in gas exchange parameters, dry matter accumulation, and partition [17,18]

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