Monday, November 5, 2007
68-3
Physiological Basis for Yield Reduction in No-till Wheat in Kentucky.
Joseph Omielan, Larry J. Grabau, and Saratha Kumudini. University of Kentucky, UK Plant & Soil Sciences, 1405 Veterans Drive, Lexington, KY 40546-0312
Production of winter wheat under no-till (NT) can have a number of economic and edaphic benefits over conventional tillage (CT) production systems. However, the adoption of NT wheat production in Kentucky has been slow due to its association with low yields. The objective of this study was to determine the physiological basis for yield reduction under NT wheat production. Two experiments were conducted. In the first experiment, main plots were two tillage systems (NT and CT), and split plots were four cultivars with different expected heading dates. In the second experiment, main plots were again NT and CT tillage systems, while the split plots were two cultivars, and split-split plots were three different seeding rates. Yield and yield component measurements were collected in both experiments. Yields under NT were less than or equal to those under CT. Biomass accumulation was not limited by NT, but this treatment did reduce harvest index (HI). This reduction in partitioning to the grain was due mainly to fewer kernels per head. The physiological changes manifested as a consequence of NT production of soft red winter wheat in this region was an increase in tillering and a reduction in partitioning to the grain relative to CT, which in some locations and years resulted in lower yields.