Assessing Impacts of Ozone on Agricultural Crops: II. Crop Yield Functions and Alternative Exposure Statistics

Abstract

A principal objective of the National Crop Loss Assessment Network (NCLAN) is to develop O/sub 3/ dose-crop yield response models for use in assessing the effects of O/sub 3/ on economically important crop species and cultivars. This paper is part of a third assessment report from NCLAN. The NCLAN is composed of several cooperating programs with field sites in different regions of the country. Open-top chambers allow control of O/sub 3/ concentration-crop yield functions for the major crops studied in 1980 and 1981, and for all crops studied during 1982. Four O/sub 3/ averaging times (exposure statistics) are used in a Weilbull model for each experimental data set. Models derived using two seasonal mean O/sub 3/ statistics (1-h/day and 7-h/day means) and two seasonal peak O/sub 3/ statistics (1-h and 7-h) are compared. The results suggest that all four O/sub 3/ statistics are of similar value when obtained from and used for the same data set. Seasonal mean O/sub 3/ statistics can be used to develop models which can be used to estimate yield of a given crop from data obtained from different sites or from different years at one site. However, peak statistics obtained from one site cannot bemore » used to predict yield from data obtained at a second site, or from data obtained at the same site in different years. 12 references, 4 tables.« less