Characterizing roots and water uptake in a ground cover rice production system.

Sen Li,Wenwen Ma,Xiaoyu Wang,Qiang Zuo,Alon Ben-Gal,Xinxin Jin,Jianchu Shi,Khawar Jabran

doi:10.1371/journal.pone.0180713

Abstract

Background and aimsWater-saving ground cover rice production systems (GCRPS) are gaining popularity in many parts of the world. We aimed to describe the characteristics of root growth, morphology, distribution, and water uptake for a GCRPS.MethodsA traditional paddy rice production system (TPRPS) was compared with GCRPS in greenhouse and field experiments. In the greenhouse, GCRPS where root zone average soil water content was kept near saturation (GCRPSsat), field capacity (GCRPSfwc) and 80% field capacity (GCRPS80%), were evaluated. In a two-year field experiment, GCRPSsat and GCRPS80% were applied.ResultsSimilar results were found in greenhouse and field experiments. Before mid-tillering the upper soil temperature was higher for GCRPS, leading to enhanced root dry weight, length, surface area, specific root length, and smaller diameter of roots but lower water uptake rate per root length compared to TPRPS. In subsequent growth stages, the reduced soil water content under GCRPS caused that the preponderance of root growth under GCRPSsat disappeared in comparison to TPRPS. Under other GCRPS treatments (GCRPSfwc and GCRPS80%), significant limitation on root growth, bigger root diameter and higher water uptake rate per root length were found.ConclusionsDiscrepancies in soil water and temperature between TPRPS and GCRPS caused adjustments to root growth, morphology, distribution and function. Even though drought stress was inevitable after mid-tillering under GCRPS, especially GCRPS80%, similar or even enhanced root water uptake capacity in comparison to TPRPS might promote allocation of photosynthetic products to shoots and increase water productivity.

Highlights

Rice (Oryza sativa L.) is one of the most important grain crops for more than 50% of the world’s population, accounting for approximately 20% of total energy intake, and an annual increase of 8–10 million tons is estimated necessary to meet future needs [1]
We aimed to describe the characteristics of root growth, morphology, distribution, and water uptake for a ground cover rice production system (GCRPS)
Before mid-tillering the upper soil temperature was higher for GCRPS, leading to enhanced root dry weight, length, surface area, specific root length, and smaller diameter of roots but lower water uptake rate per root length compared to traditional paddy rice production system (TPRPS)

Summary

Introduction

Rice (Oryza sativa L.) is one of the most important grain crops for more than 50% of the world’s population, accounting for approximately 20% of total energy intake, and an annual increase of 8–10 million tons is estimated necessary to meet future needs [1]. Increasing population and global water shortage make development of water-saving rice production technologies inevitable, especially in China [4, 5]. The most significant aspects discriminating TPRPS from GCRPS lie in the transformation of root zone soil water status from completely saturated and anaerobic to partially unsaturated and aerobic and increased temperature of the upper soil layer especially during the early growth season. These alterations in soil water and temperature are expected to affect root growth, morphology, distribution, and subsequently water uptake [14,15,16].

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