Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2009
Publication Date: 4/20/2010
Citation: Bunce, J.A. 2010. Leaf transpiration efficiency of some drought-resistant maize lines. Crop Science. 50:1409-1413.
Interpretive Summary: The increasing scarcity and cost of water for agriculture provides incentive to increase the efficiency with which crops use water. In many crop species, varieties which are highly efficient in water use have reduced yield because of lower photosynthesis. This research has shown that in corn, varieties can be found which have both high water use efficiency and high photosynthesis. This work will be of use to researchers trying to develop highly productive corn varieties with increased water use efficiency.
Technical Abstract: Field measurements of leaf gas exchange in maize often indicate stomatal conductances higher than required to provide substomatal carbon dioxide concentrations saturating to photosynthesis. Thus maize leaves often operate at lower transpiration efficiency (TE) than potentially achievable for species with C4 metabolism. I tested whether several maize lines described as drought resistant or drought tolerant operated with higher leaf TE than less drought adapted lines. Field measurements of leaf TE were conducted over two seasons for five reputedly drought resistant lines of maize and three locally grown lines not regarded as drought resistant. Mid-day photosynthesis, transpiration, stomatal conductance, and substomatal carbon dioxide concentration measurements were made under the ambient field conditions of air temperature and humidity in Beltsville, Maryland. Soil moisture was not limiting. Consistent significant differences among the lines occurred for stomatal conductance, substomatal carbon dioxide concentration, and TE, but no significant differences among the lines occurred in photosynthesis. One drought tolerant line had higher TE than all others tested, and one of the local lines had the lowest TE. It is concluded that significant genotypic variation in leaf TE exists in maize, and that TE could be improved without reducing photosynthesis.