Prediction of Daily Green Leaf Area Index for Corn
1980
Dale, Robert F. | Coelho, Dirceu T. | Gallo, K. P.
Growth and duration of green leaf area of a crop determines the percentage of incident solar radiation intercepted by the crop canopy and thereby influences canopy photosynthesis, evapotranspiration, and final yields. The objective of this study was to develop a method for predicting the green leaf area index (LAI) for corn (Zea mays L.) on a daily basis through the growing season. Weekly measurements of the green leaf area (LA) of full-season corn hybrids planted on one date in 1968 and two dates from 1969 to 1974 at the Purdue University Agronomy Farm, West Lafayette, Indiana, and air temperatures from the adjacent weather station were used to develop the model. A seasonal LAI curve was divided into three phenological periods, based upon the summation of a temperature function from date of planting to day t, ΣFTₜ. The LAIₜ during the first period (planting to silking) was described as a logistic function of population and ΣFTₜ, during the second period (silking to rapid senescence) by a linear regression of LAIₜ on population and ΣFTₜ, and during the third period (rapid senescence) by a linear regression of LAIₜ on the number of days past a ΣFTₜ threshold. LAI curves were predicted for, and tested against, independent LAI measurements. The predicted curves compard well with the LAI measurements when used on nonstressed full season hybrids similar to those from which the equations were developed.
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