Effect of Alternate Wetting and Drying Irrigation on the Nutritional Qualities of Milled Rice

Tao Song,Debatosh Das,Fuyuan Zhu,Xiaofeng Chen,Jianhua Zhang,Feng Yang,Moxian Chen

doi:10.3389/fpls.2021.721160

Abstract

Alternate wetting and drying (AWD) irrigation has been widely used to save irrigation water during rice production when compared to the traditionally continuous flooding (CF). Although the influence of AWD on water-saving potential and grain yield has been studied before, its detailed effect on grain nutritional quality in milled rice remains relatively unexplored. In this study, AWD could maintain grain yield as compared with CF. Thus, we undertook efforts to compare the nutritional traits of milled rice irrigated with AWD and CF regimes. A targeted metabolome assay on milled rice identified 74 differentially accumulated metabolites (DAMs) with 22 up- and 52 down-accumulated metabolites under AWD vs. CF. Clustering of the metabolite content obtained in this assay suggested that most of the metabolites showing significant changes belonged to “lipids,” “alkaloids,” and “phenolic acids.” In addition, total protein, starch, lipid, and amino acids content were measured to correlate it with the differential accumulation of specific metabolites detected in the metabolome. Overall, the data suggested that AWD may improve the nutritional performance of milled rice by increasing amino acids and phenolic acids and decreasing lipids and alkaloids. Our study provides research proof for the need for the optimization of irrigation to optimize rice nutritional qualities.

Highlights

Metabolites play an important role in plant growth, plant–environment interactions, and human nutrition (Saito and Matsuda, 2010; Wurtzel and Kutchan, 2016)
A field study suggested that the grain yield increased under AWD vs. continuous flooding (CF), and the rice nutritional quality increased with lower content of sulfur, calcium, iron, and arsenic, and higher contents of manganese, copper, and cadmium (Norton et al, 2017a)
In order to investigate the effect of irrigation regimes on rice yield, both the grain yield and yield components under AWD and CF were quantified

Summary

Introduction

Metabolites play an important role in plant growth, plant–environment interactions, and human nutrition (Saito and Matsuda, 2010; Wurtzel and Kutchan, 2016). Metabolite analysis serves as a reliable and detailed measure of food nutritional quality under different agricultural practices (such as irrigation regime and fertilizer application). AWD Improves Rice Nutritional Qualities as an alternative water-saving practice, the alternate wetting and drying (AWD) irrigation regime has been adopted in many Asian countries including China, Bangladesh, India, and Vietnam. Many studies were conducted on the effects of AWD on rice (Cheng et al, 2003; Norton et al, 2017a; Graham-Acquaah et al, 2019; Song et al, 2019; Dossou-Yovo and Saito, 2021). We hypothesized that the metabolite content of milled rice will be significantly affected with differences in irrigation regime depending upon the quantity of water used. We compared differences in metabolite levels for milled rice grown under AWD and CF using widely targeted UPLC–ESI-MS/MS-based metabolome assay. The results of this study would provide hints for rice production practices to obtain milled rice of improved quality

Methods

Results

Discussion

Conclusion