Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2014
Publication Date: 11/26/2014
Citation: Kebede, H.A., Sui, R., Fisher, D.K., Reddy, K.N., Bellaloui, N., Molin, W.T. 2014. Corn yield response to reduced water use at different growth stages. Agricultural Sciences. 5:1305-1315.
Interpretive Summary: Groundwater levels have declined across much of the United States including the Mississippi Delta, thus making efficient water use an issue. In the Mississippi Delta, there is frequent drought with high temperatures during the reproductive and grain fill stages of the corn plant and irrigation is required during this period to avoid yield loss. In order to develop an efficient water use in crop irrigation we need to know how much water can be reduced without decreasing yield. USDA-ARS scientists at the Crop Production Systems Research Unit and Crop Genetics Research Unit, Stoneville, MS conducted a study to determine corn growth stages at which water can be reduced without affecting grain yield. Corn yield was tested at three soil moisture levels of a silt loam soil [100% field capacity (fully irrigated), 75% field capacity and 50% field capacity] and four growth stages (late vegetative, silk, milk and dent stages). Reducing soil moisture to 75% of the field capacity of a silt loam soil starting at silking did not decrease yield significantly in this study with significant savings in water. If additional tests prove that the water savings at this level of soil moisture in a silt loam soil could cut down energy cost significantly, it may have the potential to increase net return in irrigated corn production.
Technical Abstract: To develop an efficient water use strategy for crop irrigation, we need to know how much water can be reduced without decreasing yield. A study was designed to determine corn growth stages at which water could be reduced without affecting grain yield, and at what soil moisture level water deficit stress begins in the plants in a silt loam soil. An experiment was conducted in a randomized complete block with a 3x4 factorial design in four replications, where treatments consisted of three soil moisture levels [100%, 75%, and 50% of field capacity (FC) of a silt loam soil by weight] and four growth stages [fourteen leaf stage (V14), silking (R1), milk stage (R3), and dent stage (R5)] in a greenhouse. Growth stages at the reproductive and grain fill stages of corn were selected because this study was intended for the Mississippi Delta, and in this region there is frequent drought during these growth stages making irrigation necessary for corn production, whereas there is usually adequate rainfall during the vegetative growth stages. Results from this study showed that reducing soil moisture from 100% FC (fully irrigated) to 75% FC of a silt loam soil starting at the R1 growth stage in corn did not reduce yield significantly compared to yield from the 100% FC, while saving a significant amount of water. Physiological measurements of photosynthesis and chlorophyll content from the three soil moisture treatments suggested that some level of moisture stress may have started in the 75% FC treatment. With further investigation, if savings in water at 75% FC results in a significant reduction in energy cost, it may be profitable to reduce soil moisture to 75% FC in a silt loam soil.