Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2015
Publication Date: 12/8/2015
Publication URL: http://handle.nal.usda.gov/10113/62035
Citation: Tolk, J.A., Evett, S.R., Wenwei, X., Schwartz, R.C. 2015. Constraints on water use efficiency of drought tolerant maize grown in a semi-arid environment. Field Crops Research. 186(2016)66-77.
Interpretive Summary: World population is expected to increase by several billion people by 2050 and crop production will need to be more efficient to meet this demand. Crops have a maximum yield, or yield potential, which they can produce when all growing conditions are perfect. But crop yields are often reduced by such factors as low sunlight, high temperatures, poor soils, and lack of water. Boundary functions are used to determine the yield potential of crop using the relationship between crop yield and its water use, or water use efficiency (WUE). Scientists from the ARS (Bushland, Texas) and Kansas State University developed a boundary function for maize, and compared it with the yield and water use of two drought-tolerant corn hybrids. This research found that high temperatures during the time that the corn ear was developing reduced WUE. This information is important for corn breeders because it identifies a period when the crop is more sensitive to high temperature and selection procedures can be developed to breed for improvements.
Technical Abstract: Identifying the constraints on crop water use efficiency (WUE) will help develop strategies to mitigate these limitations, potentially guiding agronomic and irrigation management strategies as well as providing needed directions in breeding. Boundary functions identify the upper limits of yield per unit of crop water use, and are useful for identifying constraints on WUE. The objectives of this research were to 1) develop a boundary function for maize using data (n=260) from research projects conducted at Bushland, TX, and 2) compare the yields of two recently developed, drought tolerant maize (Zea mays L.) hybrids with the boundary function and examine possible abiotic and biotic constraints on maximizing water use efficiency. A commercially available hybrid and an experimental hybrid were grown in 2012 (high environmental stress environment) and 2013 (moderate stress environment) in 48 weighing lysimeters containing soil monoliths of either clay loam, silt loam, sandy loam, or fine sand in a rain shelter facility. Plant density was 8 plants m-2; irrigation treatments were 50% and 80% replacement of predicted crop evapotranspiration. Environmental conditions such as differences between years in vapor pressure deficit were a significant constraint on achieving the yield potential of maize. Differences in breeding also resulted in significant differences in WUE, yield and yield components between hybrids in response to high temperatures and vapor pressure deficits during post-silking. Soil textural class was a significant constraint on WUE and harvest index (HI), with larger WUE and HI from crops in the fine sand and sandy loam compared with those of the crops in the clay loam and silt loam. Continued increases in the tolerance of maize to abiotic and biotic stresses will be necessary to maintain maize production in the southern High Plains region as irrigation water resources decline.