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.
Highlights
Cereals grains have nourished humanity since their domestication thousands of years ago and remained the most important source of calories for the majority of human population
Drought occurs in virtually all climatic regions and drought-induced crop yield loss is considered among the greatest losses in agriculture
Our results indicated that maize, the major C4 cereal species (91.7% of global C4 cereal production in 2013) had higher sensitivity than wheat, the major C3 species (42.9% of global C3 cereal production in 2013; Table 1, Fig 3). This result is surprising given that plants with C4 photosynthetic pathway usually have higher water-use efficiency than C3 plants, and considered less sensitive to drought. It has not been studied in all Poaceae family including in wheat and maize, lower chlorophyll contents and higher leaf mortality have been observed in various C4 genera (i.e., Heteropogon, Themeda, Tristachya) compared to C3 (i.e., Alloteropsis, Panicum) grasses under the same drought condition
Summary
Cereals grains have nourished humanity since their domestication thousands of years ago and remained the most important source of calories for the majority of human population. Maize and wheat alone contributed to more than 50% of global cereal production in 2013 or equal to about 1,016 and 713 million tons of grain production, respectively (Table 1). These numbers need to be increased by 60% to 110% by 2050 to meet the increasing human population, meat and dairy consumption, as well as biofuel industry [2]. Our food source heavily depends on cereals, yet their agricultural production is greatly affected by drought [4, 5]. During the last few PLOS ONE | DOI:10.1371/journal.pone.0156362 May 25, 2016
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