Sixty-six ryegrass (chieflyLolium perenneL.) populations colleeted from high-rainfall hill country were grown as spaeed plants for 3 years at Palmerston North for deseriptive analysis. All populations were highly variable and most were similar. They were mostly early heading, free seeding, but quite persistent. An unusually vigorous population came from old experimental plots in tussock grassland near Waiouru, and a very late-heading population from a terraee at Te Awa. Southland populations were ereet, small in diameter, and not very vigorous. Eastern districts of the North Island provided several unusually vigorous, leafy, erect populations, most of which came from unimproved farms with low available soil P. In general, populations from low-P sites grew better than those from high-P sites. Oversowing and topdressing did not appear to have altered the characteristics of the ryegrass populations and aspect had only a weak effect.
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