Effects of Soil Types and Irrigation Modes on Rice Root Morphophysiological Traits and Grain Quality

Can Zhao,Yajie Hu,Baowei Guo,Mengyun Chen,Qigen Dai,Zhongyang Huo,Xiaofeng Li,Weiling Wang,Ke Xu

doi:10.3390/agronomy11010120

Abstract

Soil moisture plays an important role in rice (Oryza sativa L.) root development and grain quality. However, little is known about the effects of soil type on rice root morphophysiological traits (RMTs) and grain quality under different irrigation modes. A soil-grown experiment was conducted during the 2016–2017 rice growing seasons in Yangzhou city with three soil types, namely, clay soil, loamy soil, and sandy soil, and three irrigation regimes, namely, conventional irrigation (CI, 0 kPa), alternate wetting and moderate drying (AWMD, −15 kPa), and alternate wetting and severe drying (AWSD, −25 kPa). The AWMD regime improved the RMT by 3.05–48.95% when compared with the CI and AWSD regimes, and the RMTs in loamy were 7.38–93.67% higher than those in clay and sandy soil under AWMD across 2016 and 2017. The AWMD regime improved the rice milling quality and appearance quality both in clay and loamy soil by 2.88–10.08% and 15.43–45.77%, respectively. The CI regime improved the processing quality and nutritional quality of rice in sandy soil. Both loamy and clay soils improved the rice RMTs and grain quality under an AWMD regime. The RMTs were very significantly correlated with water use efficiency, rice milling, and cooking quality and were negatively correlated with rice appearance quality. The AWMD regime can affect the rice RMT and can improve the rice grain quality in loamy soil. Our results provide a theoretical basis for the design of water-saving rice irrigation regimes and for an improvement in rice grain quality in the process of rice cultivation.

Highlights

Rice (Oryza sativa L.) is one of the most important grain crops in the world, and more than three billion people worldwide consume rice as a staple food [1]
Climatic data at the experimental sites during the trial periods are shown in Figure 1 and Table 1
The results showed a significant interaction between years and soil types in root dry weight and root shoot ratio (Tables 4–6)

Summary

Introduction

Rice (Oryza sativa L.) is one of the most important grain crops in the world, and more than three billion people worldwide consume rice as a staple food [1]. In the face of increasing water shortages, to meet the needs of the growing population, to increase rice yield, and to save water, some widely used water-saving irrigation regimes such as shallow-wet irrigation (SWI), controlled irrigation (CI), intermittent irrigation (II), and rain-gathering irrigation (RGI). In AWD, irrigation is applied a few days after water has disappeared from the surface so that, during the growing season, soil immersion and non-submerged periods alternate [10,15]. Compared with continuous flooding irrigation, this technique can significantly reduce irrigation water usage and can increase nutrient uptake, root growth, and the grain filling rates of rice [10,15,16,17]

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Discussion

Conclusion