Global Synthesis of Drought Effects on Maize and Wheat Production

Abstract

Drought has been a major cause of agricultural disaster, yet how it affects the vulnerability of maize and wheat production in combination with several co-varying factors (i.e., phenological phases, agro-climatic regions, soil texture) remains unclear. Using a data synthesis approach, this study aims to better characterize the effects of those co-varying factors with drought and to provide critical information on minimizing yield loss. We collected data from peer-reviewed publications between 1980 and 2015 which examined maize and wheat yield responses to drought using field experiments. We performed unweighted analysis using the log response ratio to calculate the bootstrapped confidence limits of yield responses and calculated drought sensitivities with regards to those co-varying factors. Our results showed that yield reduction varied with species, with wheat having lower yield reduction (20.6%) compared to maize (39.3%) at approximately 40% water reduction. Maize was also more sensitive to drought than wheat, particularly during reproductive phase and equally sensitive in the dryland and non-dryland regions. While no yield difference was observed among regions or different soil texture, wheat cultivation in the dryland was more prone to yield loss than in the non-dryland region. Informed by these results, we discuss potential causes and possible approaches that may minimize drought impacts.

Fig 1. Distribution of the locations of all the studies used in this synthesis.

The map was generated using ArcGIS 10.0 (ESRI, Redlands, CA).

Fig 2

Observed yield reduction (A) resulting from meta-analysis and their corresponding water reduction (B) for maize and wheat. Letters a and b indicate significant difference between observed water reduction level and n indicates the number of samples for each category variable that has observable water reduction.

Fig 3

Drought sensitivity of wheat (A) and maize (B), 95% confidence intervals of drought sensitivity of maize and wheat (C). Dotted lines indicate 95% prediction band.

Fig 4

Observed yield reduction (A) resulting from meta-analysis and their corresponding water reduction (B) for maize and wheat at different phenological phases. Letters a, b and c indicate significant difference between observed water reduction level and n indicates the number of samples for each category that has observable water reduction.

Fig 5

Drought sensitivity of maize and wheat at different phenological phases (A-D) and 95% confidence interval of drought sensitivity of maize and wheat experiencing drought at different phenological phases (E). Dotted lines indicate 95% prediction band.