Competition between rice and barnyard grass (Echinochloa). 2. The response to nitrogen, phosphorus and sulphur in pots

Abstract

The results are presented of four glasshouse experiments conducted at Deniliquin, New South Wales, investigating the competition between rice (Oryza sativa) and barnyard grass (Echinochloa spp.) grown on Riverina clay. A study of the response to nitrogen, phosphorus, and sulphur showed that Echinochloa tillering was favoured as level of nutrient supply increased. Echinochloa severely depressed rice tillering and yield. Delayed application of nitrogen did not result in any increase in rice yield when competing with Echinochloa. In the absence of Echinochloa competition, rice tillering and grain yield responded to both added nitrogen and phosphorus, but there was no significant yield response to sulphur. Rice panicle production (fertile tillering) was strongly influenced by nutrient supply and was, in turn, related to final grain yield of rice.