Ecological aspects of weed control in cotton in the Ord River valley, W.A. 1. Conditions affecting germination of weeds

Abstract

Germination tests on seeds of the predominant weeds in the irrigated cotton area of the Ord River valley, W.A., were carried out at different times at varying temperatures in dark germination chambers and at fluctuating temperatures under dark conditions in the glasshouse. Since many of the weed seeds failed to germinate at the time of conducting the experiments, the seed coats were treated either mechanically or with concentrated sulphuric acid. The experiments show that the range of temperatures throughout the year in the Ord valley is such that germination of most of the predominant weeds recorded in irrigated cotton during the wet season could also be expected in irrigated crops during the dry season. It became clear that temperature-germination relations alone are not sufficient to explain the field occurrence of the weeds.