Author
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Hatfield, Jerry |
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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/15/2013 Publication Date: 9/24/2014 Citation: Hatfield, J.L. 2014. Radiation use efficiency: Evaluation of cropping and management systems. Agronomy Journal. 106:1820-1827. Interpretive Summary: Crop growth is dependent upon the ability to capture light and convert that light into photosynthetic energy leading to plant biomass and grain yields. The assumption has been that the more light a plant can capture during its life cycle, the greater the production. Previous results across a number of crops have shown there is a linear relationship between light capture and total biomass produced. There have been fewer studies on the relationship between light capture and grain production and we designed a study to evaluate light capture for corn and soybean grown under different management practices which included tillage and nitrogen management. The technique to measure light capture used a non-destructive method which could be used to compare among different production systems. Measurement of light capture by the crop relative to biomass or grain yield is called radiation use efficiency and there was a better relationship when the relationships were developed for total biomass compared to grain yield. There were differences among years induced by variations in the soil water availability. This was evident in 2012 during the drought in which the plant had sufficient water to produce biomass but insufficient water to produce grain. This method can be applied to crop production to compare among cropping systems for their radiation use efficiency and the information will be of value to scientists as a technique to quantify crop response to the environment. Technical Abstract: Capture of solar radiation by plant canopies and conversion of this energy into biomass or grain has been described as radiation use efficiency. Radiation use efficiency (RUE) has been developed as a function of biomass accumulation and intercepted photosynthetically active radiation (iPAR) by the canopy and evaluated under non-limiting conditions to plant growth. This study was designed to evaluate RUE across a number of corn and soybean experiments in central Iowa with variation in tillage and management inputs to determine how RUE changed as a function of agronomic management. In these studies iPAR was derived through the use of a normalized difference vegetation index (NDVI) which is a surrogate for the PAR canopy interception term and total canopy biomass was measured at five times during the growing season from the early vegetative stage through maturity. Grain yields were obtained from each plot with both hand-harvest and combine samples. Values for RUE showed a linear relationship between biomass and iPAR for the entire growing season with the better fit when the relationship was confined to the vegetative development period. There were differences among years but management and tillage systems did not affect RUE values. Grain yield relationships to iPAR showed more variation than total biomass with yearly differences evident in the amount of iPAR during the grain-filling period suggesting that the length of the grain-filling period is a dominant factor in grain yield. Application of RUE to field scale observations will provide a method of assessing where crop productivity is limited. |
