Impact of Drought Stress on Transgenic Corn Seed Technologies in the United States: A Comparative Analysis

Abstract

Corn grain yield per acre has increased over 450% in the United States over the last 80 years. Continued increases in productivity may be aided by the advancement and adoption of improved transgenic corn seed varieties, but may be hindered by increased frequency and severity of agricultural drought. To test the hypothesis that current transgenic corn seed varieties are more drought tolerant than conventional seed varieties, stochastic frontier analysis is applied to per-acre yield functions for four alternative seed technologies using field-level, cross-section data from 2005 and 2010 surveys. Palmer's Moisture Anomaly "Z-index" for short term drought is incorporated in linear and quadratic terms for the growing season months of June, July, and August. Nine frontier regressions are estimated for each year: one for the national corn industry, one for each of four resource regions with interactions of seed variety and drought variables, and one for each of four alternative corn seed technologies with interactions of resource region and drought variables. Estimates are reported for factor elasticities, drought impacts and technical efficiencies. Results indicate that average technical efficiency is higher for certain transgenic seed varieties, yet these varieties also tend to have a larger significant negative marginal yield response to increased drought levels. Results may be sensitive to growing region, drought timing and severity, and level of technology adoption. This analysis may benefit corn producers choosing between alternative corn seed varieties and seed developers planning characteristics for future transgenic corn seed technologies.