Sequence of Changes in Maize Responding to Soil Water Deficit and Related Critical Thresholds.

Xueyan Ma,Guangsheng Zhou,Qijin He

doi:10.3389/fpls.2018.00511

Abstract

The sequence of changes in crop responding to soil water deficit and related critical thresholds are essential for better drought damage classification and drought monitoring indicators. This study was aimed to investigate the critical thresholds of maize growth and physiological characteristics responding to changing soil water and to reveal the sequence of changes in maize responding to soil water deficit both in seedling and jointing stages based on 2-year’s maize field experiment responding to six initial soil water statuses conducted in 2013 and 2014. Normal distribution tolerance limits were newly adopted to identify critical thresholds of maize growth and physiological characteristics to a wide range of soil water status. The results showed that in both stages maize growth characteristics related to plant water status [stem moisture content (SMC) and leaf moisture content (LMC)], leaf gas exchange [net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs)], and leaf area were sensitive to soil water deficit, while biomass-related characteristics were less sensitive. Under the concurrent weather conditions and agronomic managements, the critical soil water thresholds in terms of relative soil moisture of 0–30 cm depth (RSM) of maize SMC, LMC, net Pn, Tr, Gs, and leaf area were 72, 65, 62, 60, 58, and 46%, respectively, in seedling stage, and 64, 64, 51, 53, 48, and 46%, respectively, in jointing stage. It indicated that there is a sequence of changes in maize responding to soil water deficit, i.e., their response sequences as soil water deficit intensified: SMC ≥ LMC > leaf gas exchange > leaf area in both stages. This sequence of changes in maize responding to soil water deficit and related critical thresholds may be better indicators of damage classification and drought monitoring.

Highlights

Crop growth is affected by a variety of abiotic factors, such as climate, cultivation, soil fertility, water efficiency, etc. (Meng et al, 2005; Guo et al, 2010; Alkaisi et al, 2015; Testa et al, 2016)
Changes in Maize Responding to Soil Water Deficit in Seedling Stage In 2014, the first observation was conducted on 9 July, i.e., 7 days after irrigation controls
Maize plants of six irrigation treatments were all in seedling stage

Summary

Introduction

Crop growth is affected by a variety of abiotic factors, such as climate, cultivation, soil fertility, water efficiency, etc. (Meng et al, 2005; Guo et al, 2010; Alkaisi et al, 2015; Testa et al, 2016). Extensive studies on plant responses to soil water deficit at various levels (i.e., gene, cell, organ, individual) have been reported, serving a great purpose in understanding plant’s response mechanisms to soil water deficit (Blum, 1996; Tardieu, 1996; Lawlor, 2002; Yordanov et al, 2000; Neumann, 2008; Ghannoum, 2009; Anjum et al, 2011; Pinheiro and Chaves, 2011) Majority of these studies focused on qualitative impacts of soil water deficit with certain intensities on crop growth, based on experiments with very limited amounts of soil water levels

Objectives

Methods

Results

Conclusion