Monday, November 5, 2007
65-14

Impact of Cereal Grain Canopy Traits on Intercropped Legume Productivity.

Brock Blaser1, Lance R. Gibson1, and Jeremy W. Singer2. (1) Iowa State University, Iowa State University, 1021 Agronomy Hall, Ames, IA 50010-1010, (2) USDA-ARS, National Soil Tilth Laboratory, 2150 Pammel Drive, Ames, IA 50011

Winter cereal grain acreage could expand in the North Central U.S. if forage legumes can be reliably established using interseeding methods. We hypothesized that cereal grain genotype influences light transmittance to intercropped legumes, which affects plant mortality and stand productivity. The objective of this study was to evaluate the productivity of frost-seeded alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) in winter wheat (Triticum aestivum L.) and triticale (X Triticosecale Wittmack) varieties with varying canopy architecture. Cereal grains were planted at 300 seeds m-2 in early October and one alfalfa and two red clover varieties were frost-seeded at 900 seeds m-2 in March. Weekly light transmittance, legume density, and dry matter (DM) were collected during two growing seasons. Cereal grain varieties allowing more than 28% average seasonal light penetration through the leaf canopy had maximum legume DM production.  Alfalfa stand densities ranged from 60 to 140 plants m-2 and produced 1.05 to 1.51 Mg DM ha-1. Red clover plant densities ranged from 43 to 194 plants m-2 and produced an average of 1.84 Mg DM ha-1.