Competition between barley and Lolium rigidum for nitrate

Abstract

The ability of barley to compete with Lolium rigidum Gaud. was evaluated in a replacement series competition experiment under glasshouse conditions. A similar, positive response to nitrogen applications on growth, seed production and nitrogen uptake by barley and L. rigidum was found. The nitrogen level did not alter the competitive relationship between the species. There was reciprocal competition between barley and L. rigidum but, because of earlier tillering and nitrate absorption by barley, the competition from the crop was greater. L. rigidum exhibited a prolonged period of tillering and nitrate absorption and competed less with the barley. The relative yield total in the mixture was greater than 1 as a result of the different time of nitrate absorption by both species. The role of nitrogen fertilizer in the competitive relationship between the species is considered in terms of the period of application and the nitrogen salt used.