ROLLER AND HAMMER MILLING CHEAT (BROMUS-SECALINUS L) TO REDUCE GERMINATION AS AN ALTERNATIVE METHOD FOR WEED-CONTROL

Improvement of the economic return and the enhancement of the sustaina bility of wheat production depend on weed control. Cheat, Bromus secal inus L., is one of the most serious weeds infesting winter wheat (Trit icum Aestivum L.) fields. One way to control cheat will be to separate cheat from wheat in the combine and mechanically devitalize the seed. Two mills, a roller mill and a hammer mill, were investigated for the ir ability to damage, but not grind cheat seed to reduce its viability . Milling effects on cheat germination were evaluated in greenhouse po ts, in a laboratory growth chamber and in the field. Roller mill varia bles tested were the gap between rolls (from 0.1 mm to 1.1 mm) and the density of teeth on the rolls (5, and 8-teeth/cm). Germination decrea sed with decreasing roll gap and increasing Poll tooth density. The ha mmer mill dehulled the seeds and fractured 92% of the seed embryos. Ha mmer milled seeds had lowest germination and the most mechanical damag e. The combination of narrowest roll gap and higher tooth density yiel ded germination reduction that was statistically equivalent to the ham mer mill treatment The field tests results were similar to the laborat ory tests but intervening natural factors reduced germination for all treatments. Results demonstrated the feasibility of substituting mecha nical seed devitalization for herbicides to control weeds in wheat.